Category: Maharashtra State Board Notes

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 8 Respiration and Circulation students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 8 Respiration and Circulation

Respiration-

• Respiration is a biochemical process of oxidation of organic compounds in an orderly manner for the liberation of chemical energy in the form of ATP
• C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 38ATP

Organs of respiratory exchange-

1. Respiratory surface should possess the following features for efficient gaseous exchange.

• A large surface area.
• Thin, highly vascular and permeable to allow exchange of gases.
• Moist surfaces.

2. A terrestrial plant has stomata on leaves and young stems and lenticels on the stem surface for exchange of gases.

3. In animals, depending upon the complexity of organization and the surrounding medium, respiratory organs have become specialized and are usually associated with a transport system.

4. Respiratory organs In different organisms:

Organism	Respiratory surface or organ
I. Aquatic organisms
(1) Protists, sponges, coelenterates	Plasma membrane
(2) Planaria, Annelids, Amphibians	Plasma membrane, general body surface and moist skin
(3) Limulus (Arthropod)	Book gills
(4) Amphibian tadpoles, salamander and newt	External gills
(5) Fish	Internal gills

Organism	Respiratory surface or organ
II. Terrestrial organisms
(1)    Insects (2)    Arachnids (Spider and Scorpion) (3)    Reptiles, birds and mammals	Tracheal tubes and spiracles Book lungs Lungs
III. Underwater organism
Turtle	* Cloaca
Learn this as well : Only at the time of diving or when underwater, turtles perform cloacal respiration. There are a pair of accessory air bladders connected to the cloaca which can absorb oxygen from the water.

Human respiratory system-

Human respiratory system consists of nostrils, nasal chambers, pharynx, larynx, trachea, bronchi, bronchioles, lungs, aided by diaphragm and intercostal muscles.

1. Nostrils and nasal chambers :

(1) The nostrils are external openings of the nose. Oxygen rich air is taken into the body through the nostrils or external nares. Carbon dioxide and water vapour are released out of the body through the nostrils.

(2) The internal nares open into the pharynx. The space between the external and internal nares is known as nasal chamber. The nasal chamber is lined internally by mucous membrane and ciliated epithelium.

(3) The nasal chamber is divided into right and left parts by a cartilage called mesethmoid. Every nasal chamber is further divided into three regions, viz. vestibule, respiratory part and sensory part.

• Vestibule : The anteriormost part of the nasal chamber is vestibule. Hair present in this chamber prevent the dust particles from going inside.
• Respiratory part : It is the part which is richly supplied by capillaries. Air is made warm and moist in this region.
• Sensory part : The sensory epithelium lines this region. It is concerned with the detection of smell.

2. Pharynx :

• The pharynx is a short, vertical tube about 12 cm in length. The respiratory and food passages cross each other in the pharynx.
• The upper part of the pharynx is known as naso-pharynx. It conducts the air.
• The lower part is called laryngo-pharynx or oro-pharynx. It conducts food to the oesophagus.
• The tonsils are present in the pharynx. They are made of lymphatic tissue. They kill the bacteria that are trapped in mucus.

3. Larynx :

• The larynx produces sound. In males, it increases in size at puberty. This is termed as Adam’s apple.
• From the pharynx air enters the larynx. The opening through which it enters is called glottis.
• The glottis has a guarding flap called epiglottis.
• The epiglottis prevents the entry of food particles into the trachea.
• The vocal cords are seen along the side of the glottis. They are made of elastic tissue. They produce sound.
• Passage of air between the vocal cords and modulations created by tongue, teeth, lips and nasal cavity produce voice.

4. Trachea :

• The trachea or windpipe is about 10-12 cm long and 2.5 cm wide.
• It is situated in front of the oesophagus and runs downwards in the thorax.
• Fibrous muscular tissue supported by ‘C’ shaped cartilages form the walls of the trachea.
• 16 to 20 cartilage rings are present in the trachea.
• The trachea is lined internally by ciliated epithelium and mucous glands.
• Mucous and ciliary action remove the dust particles and push them upwards to the larynx. These particles are then gulped and taken into the oesophagus. Instant coughing can remove foreign particles that enter the trachea.

5. Bronchi and bronchioles :

• The trachea divides into two bronchi (singular- bronchus) at its distal end behind the sternum.
• The bronchus has complete ring of cartilage for support.
• The bronchi enter the lungs on either side.
• After entering the lungs each bronchus divides into secondary and tertiary bronchi. The tertiary bronchi divide further to form bronchioles.
• The bronchioles are minute and are without the cartilage rings in their walls.
• Each bronchiole ends into a bunch of alveoli which appear like a bunch of grapes. Each alveolus is balloon shaped.
• Many alveoli make the lung spongy and elastic.

6. Lungs :

• The lungs are principal respiratory organs located in the thoracic cavity.
• They are pinkish, soft, hollow, paired, elastic and distensible organs.
• The lung is enclosed in a pleural sac.
• The pleural sac has two membranes – an outer parietal and an inner visceral which enclose the pleural cavity.
• The pleural fluid which is present in the pleural cavity lubricates and prevents friction when pleural membranes slide on each other.
• The lungs are richly supplied with blood capillaries and hence are highly vascular organs.
• The left lung has two lobes while the right lung has three lobes.
• Each lobe has many bronchioles and alveolar sacs.
• The alveolar sacs are spherical and thin walled and contain about 20 alveoli.
• The alveoli are covered by a network of capillaries from pulmonary artery and pulmonary vein.
• Each alveolus has thin and elastic wall. It is about 0.1 mm in diameter.
• The alveolar wall is 0.0001 mm thick and is made of simple, non-ciliated, squamous epithelium. It has collagen and elastin fibres.
• Every lung has about 700 million alveoli which increase the surface area for the exchange of gases.
• The outermost covering of the lungs which is known as visceral pleura is made of smooth muscle fibres.
• The lobule in the lung consists of alveolar ducts, alveolar sacs and alveoli. In alveoli gaseous exchange takes place.

Mechanism of respiration –

1. The process of respiration includes breathing, external respiration, internal respiration and cellular respiration.

(A) Breathing :

• Breathing is the process by which the air comes in and goes out of the lungs.
• The rate of gaseous exchange is speeded up by breathing.
• Breathing is a part of respiration and the terms breathing and respiration are not synonymous.
• Inspiration and expiration together make breathing.

(i) Inspiration :

• Inspiration is an active process brought about by ribs, intercostal muscles, sternum and diaphragm.
• The intercostal muscles contract and pull the ribs outwards. This increases the space in the thoracic cavity. The lower part of sternum is simultaneously raised. The diaphragm contracts and flattens. This
  causes further increase in the volume of : thoracic cavity.
• Pressure in the lungs decreases and the volume | increases due to expansion of the lungs.
• Due to pressure difference the atmospheric * air rushes into the lungs through respiratory * passage as a result of which air is inspired * in.

(ii) Expiration :

• Expiration is the passive process.
• During expiration the intercostal muscles j relax and the ribs are pulled inwards.
• The diaphragm is relaxed and becomes ; dome-shaped.
• The volume of the thoracic cavity is reduced. :
• The pressure on the lungs is increased as a j result of which they get compressed.
• Air is thus expelled out of lungs through the j nares.

(iii) Respiratory cycle :

• Respiratory cycle is alternate inspiration and expiration process.
• In adult man there are 16 to 20 respiratory cycles per minute.
• The medulla oblongata in the brain controls the respiration.

(B) External respiration/exchange of gases at the alveolar level :

• Exchange of gases between the alveolar .air and the blood takes place through thin squamous epithelial layer of alveolus and similar layer of the capillary wall.
• Respiratory gases will always diffuse from an area of higher partial pressure to an area of lower partied pressure in these two regions.
• Due to difference in partial pressure, carbon dioxide diffuses from the capillaries into the alveolus whereas oxygen will diffuse from alveoli to the capillaries.
• Table : Pulmonary volumes and capacities :
  

(C) Internal respiration :

• Transport of O₂ : Only 3% of total oxygen is carried in a dissolved state by plasma while 97% of oxygen is carried in the form of oxyhaemoglobin from lungs to tissues.
• Oxygen dissociation curve : A sigmoid curve which shows oxygen-haemoglobin dissociation and the relationship between oxyhaemoglobin saturation and oxygen tension.
• Bohr effect : The shift of oxyhaemoglobin dissociation curve due to change in partial pressure of C02 in blood is called Bohr effect.
• Haldane effect : The effect caused by increase in hydrogen ions which results in decrease of pH of blood is called Haldane effect.

Transport of CO₂ :

• 7% of COa is transported in the form of carbonic acid by plasma.
• 70% of COa is transported from tissues to lungs in the form of sodium bicarbonate and potassium.
• Remaining 23% of COa is carried in the form of carbaminohaemoglobin.
• Hamburger’s phenomena or chloride shift : Movement of chloride ions to maintain the ionic balance between the RBCs and the plasma is called chloride shift.

(D) Cellular respiration : In this last step food is oxidized in the cell and ATP is produced and used to carry out vital processes.

2. Carbon monoxide poisoning :

• Haemoglobin has affinity for oxygen. But for carbon monoxide it has about 250 times more affinity than that of oxygen.
• With carbon monoxide it forms a stable compound called carboxyhaemoglobin.
• Due to such combination, the oxygen is not transported to the tissues. The tissues thus suffer from oxygen starvation. This leads to asphyxiation and in extreme cases death.
• Treatment of carbon monoxide poisoning is given by administering oxygen-carbon dioxide mixture to make high PO₂ level to dissociate the carbon monoxide from haemoglobin.
• Carbon monoxide poisoning occurs in closed rooms with open stoves, gas burners, automobile engines or any incomplete combustion.

Regulation of breathing-

• Normal breathing is an involuntary process controlled by inspiratory centres and expiratory centres in medulla, pneumotaxic centre in pons and apneustic centre located in medulla.
• The Hering-Breuer reflex controls the rate and depth of breathing and also prevents over inflation of lungs.
• Cerebral cortex has voluntary centres which prevent water or irritating gases from entering the lungs.

Modified respiratory movements-‘

Modified respiratory movements are used to express emotions and to clear air passages. They may be reflexes or voluntarily initiated movements such as yawning.

Common disorders of respiratory system-

1. Respiratory disorders:

Respiratory disorders	Cause and symptoms
(1) Emphysema	Cause : Cigarette smoking and air pollution Symptoms : Over inflation of the alveoli, rupture of alveolar wall.
(2) Bronchitis	Cause : Certain bacterial or viral infection, also caused by smoking and air pollution. Symptoms : Inflammation of bronchi, regular coughing with greenish-yellow sputum.
(3) Sinusitis	Cause : A viral infection or common cold Symptoms : Inflammation or swelling of the tissue lining the sinuses.
(4) Laryngitis	Cause : Certain viruses, bacteria Symptoms : Hoarseness, cough, difficulty in swallowing, inflammation of larynx and vocal cords.
(5) Pneumonia	Cause : Bacteria, viruses, mycoplasma Symptoms : Filling of air spaces of alveoli with fluid containing dead WBCs, chest pain, shortness of breath, blood in mucous.
(6) Asthma	Cause : Allergy to foreign substances like pollen, dust, certain food, food additives, animal dander, etc. Symptoms : Narrowing and inflammation of bronchi, bronchospasm, periodic wheezing, difficulty in breathing.
(7) Occupational respiratory disorders silicosis, asbestosis	Cause : Long term exposure to silica and asbestos dust in the mining industry. Symptoms : Irritation, fibrosis causing inflammation.

2. Treatment of respiratory disorders is by taking suitable antibiotics, inhalants, vaporizers and cough medicines. Also quitting smoking, using preventive masks and staying away from polluted air is too remedy against these disorders.

3. Artificial ventilation : Method of induced breathing in a person who is unable to breathe is given artificial ventilation.

4. Ventilator : A machine supporting breathing when normal breathing fails.

Transportation in living organisms-
Circulation in animals-

1. Transportation by diffusion and active transport is suitable in extremely small organisms.

2. Intracellular transport by cyclosis is shown by almost all living organisms e.g. Paramoecium, Amoeba, root hair cells of many plants and WBCs in animals.

3. Extracellular transport : In this transport water or body fluid is circulated through body cavities as in sponges and coelenterates or moved around the viscera by contraction of body wall and muscles as in roundworms or parenchymal circulation, viz. flatworms.

4. Blood vascular system in higher animals from Annelida to chordate contains

• blood as a circulating fluid,
• heart as a pumping organ and
• the blood vessels through which blood circulates.

5. Types of blood vascular system :

(1) Open circulation :

• In this type, blood finally conies out of the blood vessels and is circulated through the body cavities (haemocoel).
• Blood flows at low pressure and there is direct exchange of materials between blood and cells or tissues of the body.
• Respiratory pigment is usually absent. When present, it is dissolved in plasma of the blood, e.g. Arthropods and Molluscs.

(2) Closed circulation :

• In this type of circulation, blood is circulated all over the body through the network of blood vessels.
• Blood does not come in direct contact with cells and body tissues and the exchange of materials between the blood and cell takes place through an intermediate fluid called lymph.
• Blood flows through blood vessels at high pressure and can be regulated. Respiratory pigment like haemoglobin is present for transportation of respiratory gases, e.g. All vertebrates, higher molluscs and annelids.
• Closed circulation can be of two main types : single circulation and double circulation.

(a) Single circulation : In fishes heart shows single circulation as blood passes only once through heart during one cardiac cycle.
(b) Double circulation :

• Human heart shows double circulation as blood passes twice through the heart during one cardiac cycle. The blood follows two routes, viz. pulmonary and systemic.
• Pulmonary circulation is the circulation between the heart and the lungs. The course of blood during pulmonary circulation is from the right ventricle (by pulmonary trunk) to the left atrium (by two pairs of pulmonary veins) of heart through lungs.
• Systemic circulation is the circulation between the heart and the body organs (except lungs). The course of blood during systemic circulation is from left ventricle (by systemic aorta) to all body organs and from the body back to right atrium (by vena cavae).

Learn This As Well:
Coronary circulation is circulation to the cardiac muscles of the heart. Coronary arteries supply oxygenated blood whereas coronary veins join to form coronary sinus and collect deoxygenated blood. This sinus opens into the right atrium.

Circulatory System in Human-

1. Circulatory system in human is made up of blood vascular system and lymphatic system.
2. Blood vascular system consists of blood, heart and blood vessels.
3. Blood composition and Coagulation :

• Study of blood is called haematology.
• The bright red, slightly alkaline main circulating, fluid in the human body is blood.
• Blood is a fluid connective tissue derived from mesoderm. It has pH about 7.4.
• There are about 5 litres of blood in the body which is about 8% of the total body weight.
• Composition of blood : There are two main components of blood, viz., plasma (55%) and blood corpuscles (45%).

(i) Plasma : Plasma is a straw coloured fluid part of blood, slightly alkaline, viscous fluid consisting of 90 – 92% water and 8 – 10% of solutes.

• Solutes are 7% proteins (serum albumin, serum globulin, heparin, fibrinogen and prothrombin).
• Other solutes are nutrients (glucose, amino acids, fatty acids and glycerol).
• Nitrogenous wastes such as urea, uric acid, ammonia and creatinine.
• Gases like oxygen, carbon dioxide and nitrogen.
• Regulatory substances like enzymes and hormones.
• Inorganic substances like bicarbonates, chlorides, phosphates and sulphates of sodium, potassium, calcium, magnesium, etc.

(ii) Blood corpuscles : Blood corpuscles are of three types, viz. erythrocytes (RBCs), leucocytes (WBCs) and thrombocytes (platelets).

Red blood corpuscles/erythrocytes-

• Circular, biconcave, enucleated cells of about 7 /im in diameter and 2.5 /mi in thickness.
• RBC count is about 5.1 to 5.8 million RBCs/ cu mm in male and 4.3 to 5.2 million/cu mm in female. The average life span of RBC is about 120 days.
• Erythropoiesis is formation of RBCs. It occurs in liver and spleen in foetus and in red bone marrow in adults.
• The old RBCs are destroyed in liver and spleen.
• Polycythemia is increase while erythrocytopenia is decrease in number of RBCs.
• RBCs contain respiratory pigment called haemoglobin which helps in transport of oxygen and carbon dioxide.
• The normal haemoglobin content in adult male is 14-17 gm/100 ml of blood and 13-15 gm/100 ml of blood in adult female.
• Less amount of haemoglobin leads to anaemia.
• RBCs transport oxygen from lungs to tissues and carbon dioxide from tissues to lungs. They maintain blood pH as haemoglobin acts as a buffer. They also maintain the viscosity of the blood.
• RBCs also contains an enzyme, carbonic anhydrase.
• The haematocrit is the ratio of the volume of RBCs to total blood volume of blood. Its value is different in men and women.

White blood corpuscles/Leucocytes-

• Leucocytes are colourless, nucleated, amoeboid and phagocytic cells.
• They show diapedesis, i.e. squeezing out of blood capillaries by amoeboid movement.
• The size is about 8 to 15 fxm.
• Total WBC count is 5000 to 11000 WBCs/ cu mm of blood.
• The average life span of WBCs is about 3 to 4 days.
• Leucopoiesis or formation of WBCs. It occurs in red bone marrow, spleen, lymph nodes, tonsils, thymus and Payer’s patches.
• Leucocytosis is increase while leucopenia is decrease in the number of WBCs.
• Leukaemia or blood cancer is a pathological increase in number of WBCs.
• The dead WBCs are destroyed by phagocytosis in blood, liver and lymph nodes.
• Leucocytes are of two types, viz., granulocytes and agranulocytes.
• Granulocytes are of three types, viz. neutrophils, eosinophils and basophils.
• Agranulocytes are of two types, viz. monocytes and lymphocytes.
• Characteristics of different types of leucocytes
  

Thrombocytes/Platelets-

• Thrombocytes are smallest, non-nucleated, round and biconvex. They are of about 2.5 to 5 m in diameter. Their count is about 2.5 – 4.5 lakhs/cu mm.
• Their life span is about 5 to 10 days.
• Megakaryocytes of bone marrow form thrombocytes.
• Thrombopoiesis is the formation of platelets.
• Thrombocytosis is the increase while thrombocytopenia is the decrease in platelet count.
• Thrombocytes help in coagulation of blood by releasing thromboplastin.
• Blood clotting/coagulation of blood : Active anticoagulants like heparin and antithrombin are present in the intact blood vessels. But upon the rupture of a blood vessel, bleeding starts. The fluid blood is converted into semisolid jelly by the process of blood coagulation or clotting.”

The clotting of blood is a complicated process in which many factors (12 clotting factors) present in plasma and tissues are involved.

The event that take place during blood clotting are as follows :

• Release of thromboplastin from extrinsic source in tissue and intrinsic source in plasma at injured site through a step-wise (cascade process) process.
• Formation of enzyme prothrombinase in the blood.
• Conversion of prothrombin into thrombin by prothrombinase.
• Conversion of fibrinogen into fibrin by thrombin.
• Formation of mesh by the fibrin fibres forming the clot.
• The normal clotting time is 2 to 8 minutes.

Heart-

1. Heart is a hollow, muscular, conical organ about the size of one’s fist with broad base and narrow apex tilted towards the left.
2. It is mesodermal in origin.
3. It is situated in middle of the thoracic cavity in a space called mediastinum, between the two lungs.
4. The heart is 12 cm in length, 9 cm in breadth and 250 to 300 grams in weight.
5. Pericardium : Double layered membrane, these layers are as follows :

• Fibrous pericardium : Outer, tough layer of inelastic fibrous connective tissue.
• Serous pericardium : This inner pericardium has two layers, outer parietal layer and inner visceral layer.
• Parietal layer forms the inner lining of fibrous pericardium.
• Visceral layer or epicardium is next to heart on the outer side.
• Pericardial fluid is present between the parietal and visceral layers of serous pericardium.

6. Heart wall :

• The heart wall has three layers, viz. outer epicardium, middle myocardium and inner endocardium.
• Epicardium has single layer of flat epithelial cells called mesothelium.
• Myocardium has cardiac muscle fibres responsible for movements of the heart.
• Endocardium has single layer of flat epithelial cells called endothelium.

7. External structure of heart :

• Human heart consists of two superior, small, thin walled receiving chambers called atria or auricles and two inferior, large, thick walled, distributing chambers called ventricles.
• Atrio-ventricular groove or coronary sulcus, a transverse groove which is present between the atria and the ventricles is seen externally.
• The interventricular sulcus is present between the right and left ventricles. Coronary arteries and coronary veins are present in the sulci. The coronary veins join to form coronary sinus which opens into the right atrium.
• The right atrium receives deoxygenated blood from all over the body through superior vena cava and inferior vena cava.
• Left atrium receives oxygenated blood from lungs through two pairs of pulmonary veins.
• From the right ventricle deoxygenated blood is sent to lungs through pulmonary trunk.
• From the left ventricle oxygenated blood is sent to entire body by systemic aorta.
• Ligamentum arteriosum connects the pulmonary trunk and systemic aorta. It represents ductus arteriosus of foetus.

8. Internal structure of heart :

• There are four chambers in the heart, viz., two atria and two ventricles which can be demarcated internally.
• Atria are thin walled upper receiving chambers separated from each other by interatrial septum.
• The right atrium receives deoxygenated blood from all over the body through superior vena cava, inferior vena cava and from the heart through coronary sinus.
• The opening of inferior vena cava is guarded by Eustachian valve while the opening of coronary sinus is guarded by Thebesian valve.
• The fossa ovalis is oval depression that is present on the right side of interatrial septum. It is the remnant of foramen ovale, an oval opening in the interatrial septum of the foetus.
• The left atrium receives oxygenated blood from the lungs through four openings of pulmonary veins.
• Right and left atria open into the right and left ventricles respectively through atrioventricular apertures. These are respectively guarded by tricuspid and bicuspid valves made up of connective tissue.
• The right atrioventricular valve has three flaps hence called tricuspid valve while left atrioventricular valve has two flaps hence called bicuspid valve or mitral valve.
• These valves are attached to papillary muscles of ventricles by chordae tendinae. The valves are prevented from turning back into the atria during the contraction of ventricles due to chordae tendinae.
• Ventricles are two thick walled lower, distributing chambers separated from each other by interventricular septum.
• Left ventricle has thick wall. The inner surface of the ventricle is thrown into a series of irregular muscular ridges called columnae carnae or trabeculae carnae.
• Pulmonary trunk or aorta arises from the right ventricle carrying deoxygenated blood to lungs for oxygenation. Systemic aorta arises from the left ventricle carrying oxygenated blood to all parts of the body.
• Pulmonary aorta and systemic aorta have three semilunar valves at the base which prevent the backward flow of blood during ventricular diastole.

9. Pumping action of heart : Heartbeat is the rhythmic contraction, i.e. rhythmic contraction (systole) and relaxation (diastole) of the heart. The rate of heartbeat is about 72 times per minute during which it pumps out about 5 litres of blood which equals cardiac output.

10. Conducting system of heart :

• The heartbeat in human beings originates in modified cardiac muscles called sinoatrial node (S.A. node). Therefore, the heart is said to be myogenic.
• The conducting system of heart consists of sinoatrial node (SAN), atrioventricular node (AVN), Bundle of His and Purkinje fibres.
• The heart shows auto-rhythmicity as the impulse for its rhythmic movement during beating is developed inside the heart.
• The autorhythmic fibres are developed during embryonic life. They act as pacemaker by setting the rhythm for the heart. They also form conducting system for conducting impulses throughout heart muscles.
• The impulse travels in the heart in the following manner : Sinoatrial node (Pacemaker) → Internodal pathway → Atrioventricular node → Bundle of His → Right and left bundle branches → Purkinje fibres.

Working mechanism of human heart-

1. Cardiac cycle : One atrial systole (0.1 second), one ventricular systole (0.3 second), followed by a joint diastole (0.4 second) is called a cardiac cycle. One cardiac cycle takes place in about 0.8 second and is also called a heartbeat.

(1) Atrial systole : During atrial systole, the deoxygenated blood from the right atrium enters the right ventricle through atrioventricular aperture whereas the oxygenated blood from left atrium enters the left ventricle through atrioventricular aperture. In normal conditions atrial systole lasts for 0.1 second and atrial diastole lasts for 0. 7 second.

(2) Ventricular systole : During ventricular systole, the deoxygenated blood from the right ventricle enters the pulmonary trunk and the oxygenated blood from the left ventricle enters the aorta. The backflow of blood into atria is prevented by the closure of cuspid valves of both atrioventricular apertures (lubb sound is produced) Ventricular systole lasts for 0.3 second and ventricular diastole lasts for 0.5 second.

(3) Joint diastole or complete diastole : Both atria and ventricles undergo relaxation. During ventricular diastole the backflow of blood from pulmonary trunk and systemic aorta into respective ventricles is prevented by closure of semilunar valves (dub sound is produced). The joint diastole lasts for 0.4 second.

2. Regulation of cardiac activity :

• Cardiovascular centre present in the medulla oblongata of brain regulates the working of the heart.
• Sympathetic nerves secrete adrenaline, which increases the rate of the heart.
• Parasympathetic nerves secrete acetylcholine, which decreases the rate of the heart.
• Conditions like hypoxia, acidosis, alkalosis decrease cardiac activity whereas hormones like epinephrine and nor epinephrine increase cardiac activity (chemical control).
• Elevated level of K+ and Na+ decreases cardiac activity.

Blood vessels-

1. Blood vessels are of three types, viz. arteries, veins and capillaries.

• Arteries : Blood vessels carrying blood away from the heart are called arteries. Arteries form arterioles which in turn divide and re¬divide to form capillaries.
• Veins : Blood vessels carrying blood to the heart are called veins. They have broad lumen and show low blood pressure.
• Capillaries : Capillaries are thinnest of blood vessels and formed by division and redivision of arteriole. Capillaries unite to form venules. Venules join to form veins.

2. A chart showing the differences between arteries, veins and blood capillaries :

Angiology is the study of blood vessels.

3. Heartbeat, pulse and cardiac output :

• Heartbeat is the rhythmic contraction and relaxation of the heart.
• One systole and one diastole make one heartbeat.
• Heart rate is number of beats per minute (72 times per minute).
• Stroke volume is amount of blood pumped out of the ventricles each time (About 70 ml of blood).
• Cardiac output is amount of blood pumped out of the ventricles per minute,
  i. e 72 x 70 ml = 5040 or about 5 litres of blood per minute.
• Tachycardia is faster heart rate (Over 100 beats per minute).
• Bradycardia is slower heart rate (Over 60 beats per minute).
• Pulse is a pressure wave travelling through the arteries after each ventricular systole.
• Pulse in the radial artery at the wrist is commonly measured.
• The pulse rate per minute indicates the heart rate. It is same as that of heart rate (72 per minute).
• Pulse rate changes with age, sex, posture, exercise and emotional state.

Blood pressure (B.P.)-

1. Blood pressure : Arterial blood pressure is the lateral pressure or force exerted by flowing blood on the wall of arteries.
2. Sphygmomanometer is the instrument used for measuring the blood pressure.
3. The units of blood pressure are mm Hg millimetres of mercury).
4. Blood pressure is of two types-systolic blood pressure and diastolic blood pressure.

• Systolic blood pressure : It is the maximum pressure of blood during ventricular systole. Normal systolic pressure is 120 mm Hg.
• Diastolic blood pressure : It is the minimum pressure of blood during ventricular diastole. Normal diastolic pressure is 80 mm Hg.
• The normal blood pressure is 120/80 mm Hg.
• Pulse pressure is the difference between systolic and diastolic pressure. Normal pulse pressure is 40 mm Hg.

5. Factors affecting arterial blood pressure :

• Cardiac output
• Peripheral resistance
• Blood volume
• Length and diameter of blood vessels
• Viscosity of blood
• Age
• Gender
• Venous return
• Sleep, emotions
• Exercise, anxiety

6. Hypertension :

• Hypertension means higher values of blood pressure (More than 140/90 mm Hg blood pressure values).
• Excessive high blood pressure of about 230/120 mm Hg may cause rupturing of blood vessels of eye (causing blindness), kidney (nephritis) and brain (stroke or paralysis).
• Factors such as arteriosclerosis, atherosclerosis, obesity, physical , or emotional stress, alcoholism, smoking, cholesterol rich diet, increased secretion of renin, epinephrine or aldosterone, etc. can cause blood pressure.

7. Coronary artery disease (CAD) :

• Atherosclerosis (narrowing of coronary arteries) can cause coronary artery disease.
• In CAD the heart muscle is damaged because of an inadequate amount of blood due to obstruction of its blood supply.
• Depending on the degree of obstruction symptoms may be mild chest pain (angina pectoris) or heart attack (myocardial infarction).

8. Atherosclerosis : Deposition of fatty substances in the lining of arteries, resulting in the formation of an atherosclerotic plaque. These depositions decrease the size of the arterial lumen.

9. Angina pectoris : Angina pectoris is the pain in the chest due to reduction in blood supply to cardiac muscle caused by narrowed and hardened coronary arteries.

10. Angiography : Angiography is X-ray imaging of the cardiac blood vessels to locate the position of blockages. Remedied procedures like angioplasty or bypass surgery are carried out depending upon the degree of blockage.

11. Heart Transplant : Heart transplant is replacement of severely damaged heart by normal heart from brain-dead or recently dead donor. This procedure is necessary in patients with end-stage heart failure and severe coronary arterial disease.

12. Silent heart attack : Heart attack that lacks the general symptoms of classic heart attack like extreme chest pain, hypertension, j shortness of breath, sweating and dizziness is known as silent heart attack or silent  myocardial infarction. Men are more affected J by silent heart attack than women.

Electrocardiogram-

•  Electrocardiogram or ECG is graphic record : of electrical variations produced by the heart during one heartbeat or cardiac cycle.
• Electrocardiogram or ECG machine is the instrument used to record action potentials generated by heart muscles.
• Einthoven in 1903 discovered this technique, hence he is known as the “Father of Electrocardiography”.
• A normal ECG consists of different types of waves such as P-wave, QR S-complex wave and T-wave.
• Waves of ECG and their significance :
  
• Abnormal functioning of heart such as in coronary artery diseases, heart block, angina pectoris, tachycardia, ischemic heart disease, myocardial infarction, cardiac arrest, etc. can be diagnosed by ECG.

Lymphatic system-

1. Lymph, lymphatic capillaries, lymphatic vessels and lymph nodes together constitute lymphatic system.

• Lymph is the tissue fluid that bathes the cells and is collected in lymphatic capillaries. Lymph is a fluid connective tissue just like blood but is without RBCs, platelets and some plasma proteins. It contains carbon dioxide and metabolic wastes.
• Lymphatic capillaries are thin walled vessels interwoven with the blood capillaries, present in all the tissue spaces. They are not connected with blood capillaries and are blind at one end. Lymph capillaries are wider than blood capillaries and are lined by endothelium of thin and flat cells.
• Lymphatic vessels are formed by the union of lymphatic capillaries. These are thin walled having numerous valves to prevent backflow. Thoracic or left lymphatic duct and right lymphatic duct are the main lymphatic vessels in the body.

2. Functions of lymphatic system :

• Draining off the excess tissue fluid from the extracellular spaces back into the blood.
• Transport of carbon dioxide and metabolic wastes from the tissue fluid. Transport of lymphocytes and antibodies from the lymphatic nodes to the blood.
• Transport of absorbed fats from the intestine to the blood.
• Destruction of invading microorganisms and foreign particles in the lymph nodes.

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 7 Plant Growth and Mineral Nutrition students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 7 Plant Growth and Mineral Nutrition

Plant Growth-

1. Growth is a characteristic feature of living organisms.
2. Aspects of Growth

1. Quantitative
2. Qualitative

Quantitative: Increase in length size, volume, numbers body mass, dry weight, etc.

Qualitative

• Change in nature of growth
• Development – orderly progress
• Differentiation – complex state

3. Growth : A permanent irreversible increase in the bulk of an organism, accompanied by change in the form.

4. Growth in multicellular/vascular plants

1. Indeterminate
2. Indefinite
3. Restricted to specific regions
   Meristems -Apical, Intercalary and lateral.

5. In unicellular plants, determinate and uniform growth is observed, while in multicellular plants certain organs like leaf, flowers and fruits show determinate growth.

Phases of growth-

1. Phase of cell division/cell formation :

• Meristematic cells – thin walled cells
• Mitotic division → 2 cells → out of these one remains meristematic and other undergoes differentiation.
• Slow rate of growth – i.e. Lag phase

2. Phase of cell enlargement/cell elongation :

• Newly formed cell absorbs water and becomes turgid.
• Osmotically active cell → Turgidity leads to cell enlargement
• Synthesis of new wall material
• Accelerated pace of growth – Log phase or exponential

3. Phase of cell maturation / Cell differentiation :

• Enlarged cell become specialized
• Cells attain maturity – morphological and physiological features
• Cells get equipped to perform specific function
• Steady state, rate of growth slow down -stationary phase

Conditions for growth-

1. Physiological conditions

2. Environmental Conditions

Growth rate and types of growth –

1. Growth in plants can be measured as increase in

2. Various methods for measurement of linear growth :

• Direct method : Measurement with scale
• Horizontal microscope : Useful for measuring growth in fields.
• Auxanometer : For linear growth of shoot – 2 types – Arc auxanometer and Pfeffer’s auxanometer.
• Crescograph : Record of primary growth, information of growth per second. It is developed by Sir J. C. Bose.

3. Growth Rate/Efficiency index : Increased growth per unit time. e.g. Increase in area of leaf, size of flower, etc.
4. Absolute growth rate (AGR) : Ratio of change in cell number (dn) over time interval (dt)
i. e. AGR = \(\frac{d n}{d t}\) i.e. total growth per unit time.
5. Relative growth ratio (RGR) : AGR when divided by total number of cells present i.e. growth of given system i.e. RGR = \(\frac{\mathrm{AGR}}{n}\)i.e. ratio of growth in given time / initial growth.
6. For describing cell growth in culture AGR and RGR are useful.
7. Types of Growth

• Arithmetic
• Geometric:

Arithmetic

• Rate of growth constant hence linear curve
• e.g. elongation of root
• Mitosis of cell → 2 cells one divides further and other differentiation and maturation
• Mathematical expression Lt = L₀ + rt

Where Lt = Length at time ‘t’
L₀ = Length at time zero
r = Growth rate
t = Time of growth

Geometric:

• Rate of growth slow initially and then exponential rate. J shaped curve.
• e.g. Embro – Initial stages of zygote division
  Mitosis of cell → 2 cells
  Both cells continue to divide and
  redivide
• Mathematical expression
  W₁ = W₀e^rt

Where W₁ = Final size
W₀ = Initial size
e = base of natural log
r = Growth rate
t = time of growth.

Growth curve-

1. Graphic representation of the total growth against time is known as growth CurVe.
2. Types of Growth curve – Graphs
   
3. Growth rate is low in lag phase, faster growth rate reaching maximum in exponential or log phase and is gradually slows down in stationary phase. –
4. Sigmoid curve is obtained when rate of growth plotted against time for all three phases.
5. Grand period of growth (GPG) : The total period required for all phases (Lag, log and stationary) to occur is called grand period of growth.

Differentiation, De-differentiation, Re-differentiation-

1. Differentiation : It is the permanent change in structure and function of cells leading to maturation.

• Maturation of cells derived from apical meristems.
• Major anatomical and physiological changes occur.

2. De-differentiation : It is a process or ability where living differentiated cells regain the capacity to divide thus permanent cells become meristematic. e.g. Cork cambium, Parenchyma cells forming interfascicular cambium for secondary growth.

3. Re-differentiation : The de-differentiated cells lose their capacity to divide and mature for the specific function, e.g. Secondary xylem and secondary phloem formed from de-differentiated cambium.

Development-

• It is an orderly process of progressive changes in shape, its form and also complexity.
• In plant it includes all sequential events in its life cycle, viz. – Seed germination → Meristem → Cell division → Plasmatic growth → Cell elongation → Cell maturation → Mature cell → Senescence → Death
• Thus growth, morphogenesis, maturation and senescence are included in development.

Plasticity-

• Plasticity : It is capacity of being moulded or modelled.
• In plants, plasticity is ability to form different types of structures in response to external environmental stimuli or internal stimuli. (Intrinsic plasticity)
• Plasticity is noticed in various phases of life. e.g. different form’s of leaves in same plant – cotton, coriander, larkspur (Delphinium) i.e. heterophylly in juvenile and adult stage.
• Environmental Plasicity is observed in Butter cup (Ranunculus Flabellasis).
  Heterophylly where aquatic habitat has dissected leaves and in terrestrial habitat broadly lobed leaves.

Growth Hormones-

• Starling coined the term hormone in animal physiology.
• Growth Regulators or Growth Hormones – These are the internal factors which influence growth i.e. inhibit, promote or modify growth.
• Growth Harmones:

Growth promoters	Growth inhibitors	Growth regulators
Auxins Gibberellins (GA) Cytokinins (CK)	Ethylene (gaseous) Abscissic acid (ABA)	All phytohormones

• Plant hormones are organic substances produced naturally that affect growth or other physiological functions at a site away from their place of production.
• To evoke the response hormones are needed in very small amount and they are mainly transported through phloem parenchyma.

6. Auxins : Term given by F.W. Went

• First isolated from human urine, while in plants synthesised in apical meristematic region.
• LAA – i.e. Indole 3 acetic acid – most common natural auxin, synthesised from amino acid Tryptophan.
• Synthetic auxins – IBA (Indole butyric acid), NAA (Naphthalene acetic acid), 2, 4-D (dichloro Phenoxy acetic acid).

Physiological effects and applications of auxins :

• Cell elongation and cell enlargement
• Apical dominance – Growing apical bud inhibits growth of lateral buds
• Stimulation of growth of root and stem
• Multiplication of cells hence utilized in tissue culture
• Formation of lateral and adventitious roots
• 2, 4-D is selective herbicide – kills dicot weeds
• Induced parthenocarpy – seedless grapes, : banana, lemon, orange
• Promote cell division and early differentiation I of vascular tissue xylem and phloem.
• Induces early rooting in cutting method of : artificial vegetative propagation.
• Foliar spray of synthetic auxins – Flowering ; induced in litchi and pineapple, prevents : early fruit drop of apple, pear and oranges, prevents formation of abscission layer.
• Increase in rate of respiration.
• Break seed dormancy and promote seed germination.

Gibberellins (GA) : Named by Yabuta and Sumuki:

• First isolated from fungus Gibberella fujikuroi by Kurasawa.
• Rice seedlings show Bakane disease with stem elongation due to this fungus infestation. ;
• Yabuta and Sumuki isolated it from fungus culture.
• Synthesised from mevalonic acid in young leaves, seeds and root, stem tips.
• GA₃ is most common and biologically active – Contains gibbeane ring.

Physiological effects and applications of Gibberellins :

• Breaking of bud dormancy, seed dormancy,
• By promoting synthesis of amylase in cereals, their seed germination can be stimulated e.g. wheat, barley.
• Increase in length of internodes thereby elongation of stem.
• Bolting in rosette plants – elongation of internodes before flowering e.g. Cabbage, beet.
• Parthenocarpy in tomato, apple, pear.
• Stimulates flowering in long day plants.
• Increase in fruit size and bunch length e.g. grapes.
• Overcomes effects of vernalization.
• Inhibition of root growth, delay senescence and abscission. .
• Production of male flowers on female plants.
• They convert genetically dwarf plants to phenotypically tall plants e.g. maize.

Cytokinin : Term coined by Letham.

• Promote cell division – Natural source – Banana flowers, apple and tomato fruits.
• Discovered by Skoog and Miller in Callus culture of Tobacco – by supplementing media with coconut milk.
• Present in herring (fish) sperm DNA – Kinetin.
• Cytokinins are derivatives of adenine, a purine base. Chemically 6-furfuryl amino purine.
• First natural cytokinin obtained by Letham from maize grain Zeatin.
• Synthetic hormone – 6 benzyl adenine.
• Important in plant tissue culture (callus) for morphogenesis.

Physiological effects and applications of cytokinin :

• Promote cell division and cell enlargement
• Promote shoot formation, buds
• Cytokinin and auxin ratio controls morphogenesis.
• Growth of lateral buds, controls apical dominance
• Delay of ageing and senescence, also abscission
• Formation of interfascicular cambium
• Breaks dormancy, promotes germination
• Reverse apical dominance effect
• Induce RNA synthesis

9. Ethylene : Denny reported effect in fruit ripening.

• Gane reported natural synthesis of this gaseous hormone in plants.
• Synthesised in roots, shoot apical meristems and fruits during ripening.
• It is an unsaturated, colourless, hydrocarbon gas
• Commercially used source – Ethephon
• Described as ripening hormone.

Physiological effects and applications of ethylene :

• Promotes ripening of fruits
• Stimulates initiation of lateral roots
• Breaks dormancy of buds and seeds.
• Acceleration of abscission activity by forming abscission layer.
• Inhibits growth of lateral buds, i.e. apical dominance.
• Retardation of flowering.
• Enhancement of senescence.
• Epinasty – Drooping of leaves and flowers e.g. Pineapple.
• Degreening effect – Stimulate activity of enzyme chlorophyllase causing loss of green colour in fruits of Banana, Citrus.

Abscissic Acid :

• Responsible for shedding of cotton balls and was named as abscisin I and II by Carns and Addicott.
• Isolated from buds of Acer that causes bud dormancy, substance named Dormin by Wareing.
• These substances were renamed abscissic acid, chemically 15 – C sesquiterpenoid – synthesised from mevalonic acid.
• Leaves, fruits, roots, seeds synthesise this.

Physiological effects and applications of ABA :

• Promote abscission of leaves – beneficial for stress – drought
• Induces dormancy in buds and seeds.
• Accelerates senescence of leaves, flowers and fruits.
• Delay of cell division, cell elongation and suppression of cambial activity – Inhibit mitosis.
• Causes efflux of K ions from guard cells and thus closure of stomata – used as
  antitranspirant.
• Stress hormone – Overcome stress by inducing dormancy, inhibiting growth thus face adverse environmental conditions.
• Inhibit flowering in long day plants and stimulate flowering in short day plants. Inhibits growth stimulated by gibberellin.

Photoperiodism-

1. Influence on Reproductive Growth –

Flowering :

1. Environmental factors
2. Nutritional factors

Environmental factors:

• Light -> Photoperiodism factors
• Temperature -> Vernalization

2. Effects of Light

Processes affected:

1. Seed germination
2. VegetatIve growth
3. PhotosynthesIs

Mode/manner/aspect:

1. Quality of light
2. Intensity of light
3. Duration of light

3. Photoperiodism – Term coined by Garner and Allard.
4. Duration of light has a major effect on flowering.
5. Response of plants to the relative length of light and dark periods with reference to flower initiation is called photoperiodism.
6. Critical photoperiod : It is that duration of photoperiod above or below which flowering occurs.

7. Classification of plants based on photoperiodism:

8. Short Day Plants (SDP) or Long night plants Winter flowering

• Show flowering when day length is shorter than the critical photoperiod.
• These plants need long uninterrupted dark period.
• Flowering in SDP is affected if the dark period is interrupted even by short duration (Flash : of light).

9. Long Day Plants (LDP) or Short night plants : Summer flowering

• Show flowering when longer duration of light than the critical photoperiod.
• These plants need short dark period.
• Flowering is observed if long dark period is interrupted by brief light exposure (flash).

10. Day neutral plants (DNP) :

• Flowering in these plants is independent of duration of light.
• No requirement of specific dark or light period.
• Flowering is observed throughout the year.

11. Phytochrome : Discovered by Hendricks and ; Borthwick.

• Pigment system in plants that receives the stimulus for photoperiodism.
• In short day plants, flowering is not observed if dark period is interrupted by brief exposure to red light of 660 nm but if it is exposed immediately to far red light of 730 nm flowering is observed.
• Proteinaceous pigments present in leaves.
• Exist in two interconvertible forms P_r and P_fr.
• P_fr absorbs far red light and it is changed to P_r and when P_r absorbs red light it is changed to P_fr (biologically active form).
• Phytochromes are situated in cell membrane of chlorophyllous cells of leaves.

12. During day time Pfr accumulates in leaves and stimulates flowering in LDP but inhibits flowering in SDP
13. During night (dark) Pfr converted to Pr ‘and stimulate flowering in SDP but inhibits flowering in LDP
14. In plants, morphogenesis is controlled by both light and phytochromes and hence it is known as photomorphogenesis.
15. Photoperiodic stimulus is chemical stimulus called florigen which is hormonal in nature and is transported through phloem.

Vernalization-

• It is influence of low temperature on flowering in plants. The term vernalization was coined by Lysenko.
• Temperature influences several physiological processes and reproductory growth i.e. flowering.
• Klippart observed low temperature or chilling treatment is responsible for stimulus of early flowering.
• The seeds or seedlings are exposed to low temperatures of 1 – 6° C for about a month’s duration.
• The shoot apical meristem receives stimulus in seedlings.
• Effective in seed stage (embryo) for annual plants. Cereals and crucifers show response to low temperature pretreatments.
• The stimulus is in the form of chemical substance which is proved by grafting experiment by Melcher. It is Vernalin.
• Devernalization : It is reversal of vernalization by high temperature treatment.

Advantages:

• Crops can be produced earlier.
• Cultivation of crop possible where they do not occur naturally.

Mineral Nutrition-

1. Minerals are required by plants for synthesis of food material, i.e. inorganic substances are raw materials.
2. Soil is chief source : Solid, inorganic materials are obtained from earth’s crust.
3. Air and water are other sources from surroundings.
4. Minerals are absorbed in dissolved form usually through roots.
5. Sources of minerals :

• Atmosphere : Carbon as Carbon dioxide, Oxygen
• Water : Hydrogen, Oxygen

6. C, H, O are non-mineral major elements, structural components.
7. Classification of minerals – Based on need

1. Essential
2. Non-Essential

Essential

• Without these life cycle of plants cannot be completed.
• Important structural and functional (physiological role)
• Their unavailability causes major deficiency symptoms. e.g. C,H,O,N,R

Non-Essential

• Not indispensable for completion of life cycle.
• Do not produce or cause major deficiency.
• Needed only at specific time during growth. E.g. Bo, SI, Al

8. Classification based on requirement – quantity

1. Mac roelements
2. Microelements

Mac roelements:

• Major elements
• Required in bulk or in large amounts
• Important role in nutrition
•  Structural componcnts
  e.g. CalcIum — Ca (cell vall)
  e.g. C, H. O. R N, K, Mg. S.

Microelements:

• Minor elements
• Required in traces or small amounts
• Role as cofactors
• Act as Catalysts, activators
  e.g. Zn, Cu, Al, SI, Mn, B.

9. Recent classification is based on their functional role, i.e. on the basis of biochemical functions.
10. Symptoms of Mineral deficiency in plants :
Any visible deviation from the normal structure and function of plant is called symptom.
11. Critical concentration : Required amount or the concentration of essential element below which plant growth is retarded or affected is called critical concentration.
12. Indication of deficiency is in the form of morphological changes. It may be related to the mobility of the element in the plant body.

13. Important symptoms visible in plants :

14. Role of Mineral Elements in Plants :

15. Toxicity of Micronutrients :
Condition of toxicity : When dry weight of tissues is reduced by 10% due to mineral ion concentration it is considered as toxic to plant.

16. Uptake of one element may be affected or inhibited by toxicity of other. For e.g. Mn competes with Fe and Mg for uptake by root system and inhibits translocation of Ca to shoot apex. It leads to deficiency of Ca, Mg and Fe.

17. Mineral salt absorption : In soil minerals exist as charged particles and mineral absorption is independent of water absorption.

18. Methods of Mineral absorption

1. Passive absorption
2. Active absorption

Passive absorption

• No expenditure of energy
• By diffusion
• Direct or indirect ion exchange
• Mass flow
• Donnan equilibrium

Active absorption:

• ExpendIture of energy
• Move against concentration gradient
• ATP energy from respiration
• Accumulation of ions in root hair

19. Donnan equilibrium : Some anions after their entry inside the cell get accumulated on inner side of cell membrane.

20. Additional cations are needed to balance these accumulated anions, thus the cation concentration becomes more as they get accumulated.

21. This transport from exterior against their own concentration gradient for either cations or anions is Donnan equilibrium, which is for neutralizing the effect of accumulated cations/ anions.

22. Active absorption : It needs ATP energy which is supplied to roots from respiration. Hence when there is scarcity of oxygen available to roots there is less absorption of minerals.

23. Mineral ions accumulated in root hair reach xylem through cortical cells and further along with water carried upwards.

24. They are assimilated in organic molecules and carried further with phloem to other parts i.e. redistribution.

25. A carrier concept, where membrane proteins of root cell membrane may pump these ions into cytoplasm is suggested.

Nitrogen Cycle –

• The cyclic movement of nitrogen between atmosphere, biosphere (organisms) and soil in natural processes is a nitrogen cycle.
• Nitrogen available to plants from the environment is inert and they need it in reactive form mainly nitrate ions to utilize in synthetic processes.
• Nitrogen is a limiting element which affects productivity.
• Through biological and physical fixation it is made available to plants.
• Nitrogen fixation : Conversion of free nitrogen into nitrogenous salts to make it available to plants is called nitrogen fixation.

Nitrogen Fixation-

Physical nitrogen fixation – Atmosphere

Industrial nitrogen fixation : Haber – Bosch process

• Urea is less toxic and it is used as fertilizer.
• About 80% of nitrogen found in human tissues originate from Haber-Bosch process.

Biological nitrogen fixation :

• High energy requiring process
• To fix each molecule of nitrogen to ammonia need is 16 ATE
• Ammonia is toxic it is converted to amino acids -> Proteins

Nitrification : e.g. different soil bacteria – aerobic forms – Chemoautotrophs

• Two step process
• Ammonia converted to nitrogen dioxide (nitrite) HNOa by Nitrosomonas and Nitrosococcus.
• Nitrite converted to Nitrate by addition of oxygen by bacteria Nitrobacter.

Symbiotic N₂ fixation : e.g. Root nodules of Fabaceae plants – Pea, Bean, Gram, Groundnut have Rhizobium bacteria in it. Rhizobium also seen in soil.

Ammonification : e.g. Decomposers – Fungi, bacteria, actinomycetes
After death and decay of living organisms, ammonia is made available to plants and other microbes.

Nitrogen assimilation :

• Soil reservoir has nitrogen in nitrate, nitrite and ammonia (NH₄^–) i.e. ammonium ion.
• Uptake of these available forms from soil by plants converts and incorporates them in amino acids, nucleic acids (DNA) like organic compounds – This is assimilation.
  • In the form of biomolecules Nitrogen moves through food chain and then to decomposers.
  • Amino acids are transported to different parts for synthesis of required proteins.

Amino acid synthesis

1. Reductive aminatlon
2. Transamination

Reductive aminatlon:

• E.g. Ammonia reacting with a Ketoglutaric acid to form glutamic acid.
• Reduction reaction

Transamination:

• Glutamic acid reacting with oxaloacetic acid (OAA) to form Aspartic acid.
• Reduction reaction 2. Transfer of amino group to other Carboxylic acid

Amidation : Process of formation of amides.

• Amino acids may incorporate ammonia to produce amides. Thus these are amino acids with two amino groups.
• In presence of ATP extra amino group is attached to acidic (-COOH) group.
  
• Amides are transported via xylem vessels.

Denitrification : e.g. Anaerobic bacteria.

• Soil nitrates are converted to nitrogen gas.
• Denitrifying bacteria thus return back nitrogen from ecosystem to atmosphere.
• 2NO₃ → 2NO₂ 2NO → N₂↑
  Nitrate → Nitrous oxide → Nitric oxide → Nitrogen gas
• e.g. Bacillus spp, Paracoccus spp, Pseudomonas denitrificans.

Sedimentation : Nitrates of soil are washed away with running water or leached deep with percolating water. Thus they get accumulated and remain in the form of sediments locked and away from free circulation.

By going through these Maharashtra State Board 12th Science Chemistry Notes Chapter 16 Green Chemistry and Nanochemistry students can recall all the concepts quickly.

Maharashtra State Board 12th Chemistry Notes Chapter 16 Green Chemistry and Nanochemistry

Green chemistry: Green chemistry is the use of chemistry for pollution prevention and it designs
the chemical products and processes that reduce or eliminate the use of generation of hazardous
substances.

Sustainable development: Sustainable development is the development that meets the needs of
the present, without compromising the ability of future generations to meet their own needs.

Twelve principles of green chemistry: Twelve principles of green chemistry were proposed by Paul T. Anastas and John Warner.

12 Principles of Green Chemistry –

1. Prevention of waste or by-products
2. Atom economy
3. Less hazardous chemical synthesis
4. Designing safer chemicals
5. Use safer solvent and auxiliaries
6. Design for energy efficiency
7. Use of renewable feedstocks
8. Reduce derivatives (Minimization of steps)
9. Use of catalysis
10. Design for degradation
11. Real-time analysis for pollution prevention
12. Safer chemistry for accident prevention

The role of Green chemistry:

• Promoting innovative chemical technology to design, manufacture, and use chemical products that eliminate the generation of hazardous chemicals.
• The capital expenditure required for the prevention of pollution is controlled by the use of green chemistry.
• Green chemistry helps to protect the presence of ozone in the stratosphere.
• Global warming (The greenhouse effect) is controlled by green chemistry.

Introduction to nanochemistry:

(i) Nanoscience: Nanoscience is the study of phenomena and manipulation of materials at atomic, molecular, and macromolecular scales where properties differ significantly from those at a larger scale.

(ii) Nanotechnology: Nanotechnology is the design, characterization, production, and application of structures, devices, and systems by controlling shape and size at the nanometer scale (1 -100 nm) (1 nm = 10^-9 m). Today from clothes to computer hard drives to DVD, CD players, and even cleaning products, nanotechnology plays a big part in the manufacturing of materials.

(iii) Nanomaterial: The nanomaterial is a material having structural components with at least one dimension in the nanometer scale that is 1-100 nm. Nanomaterials are larger than single atoms but smaller than bacteria and cells. These may be nanoparticles, nanowires, nanotubes, and thin films according to dimensions. They can be further classified as zero, one, and two nanomaterial dimensions.

(iv) Nanochemistry: It is the combination of chemistry and nanoscience. It deals with designing and synthesis of materials of nanoscale with different sizes and shape, structure and composition, and their organization into functional architectures. Nanochemistry is used in chemical, physical, material science, as well as engineering, biological and medical applications.

Characteristic features of nanoparticles: Characteristic features of nanoparticles are colour, surface area, catalytic activity, thermal properties, mechanical properties, and electrical conductivity.

Synthesis of nanomaterials: (1) Bottom-up approach (2) Top-down approach.

Wet chemical synthesis of nanomaterials: A sol-gel process is an inorganic polymerization reaction. It is generally carried out at room temperature and includes four steps: hydrolysis, polycondensation, drying, and thermal decomposition. This method is widely used to prepare oxidic materials.
The reactions involved in the sol-gel process are as follows :
MOR + H₂O → MOH + ROH (hydrolysis)
metal alkoxide
MOH + ROM → M-O-M + ROH (condensation)

Analysis or characterization of nanomaterials: The nanomaterial synthesized is analyzed using the following techniques.

Name of Technique	Instrument used	Information
1. UV-visible spectroscopy	UV-visible spectrophotometer	Preliminary confirmation of formation of nanoparticles
2. X-ray Diffraction (XRD)	X-ray diffractometer	Particle size, crystal structure, geometry
3. Scanning electron microscopy	Scanning electron microscope (SEM)	Structure of surface of the material that is morphology
4. Transmission electron microscopy	Transmission electron micro­scope (TEM)	Particle size
5. FTIR Fourier transform infrared spectroscopy	Fourier transform infrared spectrophotometer	Absorption of functional groups, Binding nature.

Different types of nanomaterials which can be synthesized are shown in the following figures:

Applications of nanoparticles:

• Nanoparticles are used in the manufacture of scratchproof eyeglasses, transport, sunscreen, crack-resistant paints, etc.
• It is used in electronic devices like Magnetoresistive Random Access Memory (MRAM).
• Silver nanoparticles are used in water purification systems to get safe drinking water.
• It is used in medicines.
• It is used in self-cleaning materials (lotus effect).

Advantages and disadvantages of nanoparticles and nanotechnology :

Advantages:

• Revolution in electronics and computing.
• Nanotechnology makes solar power more economical and energy storage more efficient.
• Nanotechnology is used in the manufacture of smart drugs which cure life-threatening diseases faster and without side effects.

Disadvantages :

• Nanotechnology causes environmental pollution which is dangerous for living organisms.
• Nanoparticles can cause lung damage.

By going through these Maharashtra State Board 12th Science Chemistry Notes Chapter 15 Introduction to Polymer Chemistry students can recall all the concepts quickly.

Maharashtra State Board 12th Chemistry Notes Chapter 15 Introduction to Polymer Chemistry

Classification of Polymers-

1. Based on source or origin
2. Based on structure
3. Based on intermolecular forces
4. Based on the mode of polymerization
5. No. of monomers
6. Biodegradability

Based on source or origin:

• Natural Jute, linen
• Synthetic Nylon, terylene
• Semisynthetic Acetate, rayon

Based on structure:

• Linear Polyethene
• Branched-chain Polypropylene
• Cross-linked vulcanized rubber melamine

Based on intermolecular forces:

• Elastomers Neoprene
• Fibres Nylon-6 polyesters
• Thermoplastic PVC, Polystyrene
• Thermosetting Bakelite

Based on mode of polymerization:

• Addition Polyvinyl chloride
• Condensation Nylon polyester dacron
• Ring-opening Nylon-6

No. of monomers:

• Homopolymers Polyacrylonitrile
• Copolymers Buna-S, Buna-N

Biodegradability:

• Biodegradable PHBV
• Non- biodegradable Bakelite, Nylon

Natural rubber: It is a linear polymer of isoprene (2-methyl-1, 3-butadiene), Cis isomer, exhibits elastic property.

Vulcanization of rubber: The effect of vulcanization enhances the properties like stiffness elasticity, toughness etc. of natural rubber
Natural rubber +1-3% sulphur → Rubber is very soft
Natural rubber + 20-30% sulphur → Rubber is hard.

Polyethene:

(1) LDP (Low-density polyethylene)

(2) HDP (High density polyethylene)

(3) Teflon :

(4) Polyacrylonitrile :

(5) Condensation polymerization. (Polyamide, polyester fibres)

Example : Nylon-6, Nylon-66, Terylene.

(6) Preparation of bakelite :
Formaldehyde + Phenol → Novolac → Bakelite
Other polymers of formaldehyde

1. with urea (NH₂CONH₂) → Moulded plastic
2. with melamine: formaldehyde + melamine → monomer formaldehyde melamine polymer

(7) Preparation of synthetic rubber :

• Buna-S (SBR) Styrene-butadiene rubber
  Styrene + 1, 3-butadiene → Buna-S
• Neoprene rubber
  

(8) Semisynthetic fiber:

(9) Biodegradable polymers :

PHBV (polyhydroxy butyrate-CO-β hydroxy valerate)
3-Hydroxy butanoic acid + 3 Hydroxy pentanoic acid PHBV (ester linkage)

Nylon-2-nylon-6
Glycine + amino caproic acid → Nylon -2-nylon-6

(10) Commercially important polymers :

• Perspex/acrylic glass
• Buna N
• PVC
• Polyacryl amide
• Urea-formaldehyde resin
• Glyptal
• Polycarbonate
• Thermocol.

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 11 Enhancement of Food Production students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 11 Enhancement of Food Production

Improvement in Food Production-

• Food: It is defined as any solid or liquid substance, which is swallowed, digested and assimilated in the body to keep us well.
• It is an organic, energy-rich, non-poisonous, edible, and nourishing substance.
• Importance of food: It gives us energy for all body activities. It keeps us alive, strong and healthy.

Plant breeding-

1. Plant breeding involves the improvement or purposeful manipulation in the heredity of crops and the production of new superior varieties of crops.
2. It involves genetic alteration of plants to increase their value and utility.
3. Objectives of plant breeding : Some objectives of plant breeding are common (as given below) and some vary according to type and use of the plant.

• To increase crop yield.
• To improve quality of produce.
• To increase tolerance to environmental stresses.
• To develop varieties of plants resistant to pathogens and insect pest.
• To alter the lifespan.

4. Different methods of plant breeding : Introduction, selection, hybridization, mutation breeding, polyploidy breeding, tissue culture, r-DNA technology, SCP (Single cell protein).

5. The present day crops are the result of domestication and acclimatization.
A. Hybridization and its technique :

• Hybridization is an effective means of combining the desirable characters of two or more varieties.
• New genetic combinations can be created by hybridization.
• It exploits and utilizes hybrid-vigour.

4. Types of Hybridization :

• Intravarietal (between plants of same variety)
• Intervarietal (between two varieties of the same species)
• Interspecific (between two species of the same genus)
• Intergeneric (between two genera of the same family)
• Wide/distant crosses : Crosses between distantly related parental plants. Interspecific and intergeneric hybrids are rare to occur in the nature.

5. The main steps of the plant breeding program (Hybridization) :

(1) Collection of variability :

• Germplasm collection : The entire collection having all the diverse alleles (i.e. variations) of all genes in a given crop.
• Germplasm conservation :
  • In situ conservation : Done with the help of forests and Natural Reserves.
  • Ex situ conservation : Done through botanical gardens, seed banks, etc.

(2) Evaluation and selection of parents
(3) Hybridization
(4) Selection and testing of superior recombinants
(5) Testing, release and commercialization of new cultivars

6. Green revolution :

• Green revolution is the development of high- yielding improved varieties of wheat and rice through techniques of plant breeding, in the decade from 1961, which helped the farmers to attain record production of agricultural crops in our country.
• Basic elements for Green revolution : The use of seeds of improved varieties of crops for cultivation, expansion of land for cultivation (farm land), optimum use of pesticides and fertilizers, multiple cropping system, modern farm machinery and proper irrigation system.
• Dr. Norman E. Borlaug was awarded the Nobel prize for developing the semi-dwarf varieties of wheat at international centre for wheat and maize.

Steps of hybridization

Germplasm collection:

• Evaluation and selection of parents with different qualities
• Obtaining pure lines by selfing of selected parents for three to four generations
• Identification of parents as male parent (donor) and female parent (recurrent)
• Collection of pollen grains from the flowers of male parent
• Emasculation of flowers of the female parent before anthesis
• Artificial cross (dusting of pollen grains collected from male parent on the stigma of emasculated flowers)
• Bagging, tagging of the emasculated flower of female parent
• Development of fruits and F₁ seeds
• Selection and testing of F₁ hybrid for combination of desirable characters
• Field trials for yield (productivity)
• Testing and the release of variety

7. Indian Hybrid Crops :

(1) Wheat and Rice :

• Hybrid wheat varieties in India : Sonalika and Kalyan Sona
• Semi-dwarf rice varieties in India : Jaya, Padma and Ratna
• Semi-dwarf rice varieties were developed from IR-8 (International Rice Research Institute) and Taichung native-I (from Taiwan) and introduced in India.

(2) Sugar cane :

• Saccharum barberi : Native of North India and it has poor yield and sugar content.
• S. officinarum : Grown in South India, has thicker stem and high sugar contents, but it does not grow well in North India.
• Hybrid varieties developed by crossing these two species have desirable combinations of characters like high sugar content, thicker stem and the ability to grow in North India.
• Sugar cane varieties developed at Coimbatore, Tamil Nadu : CO-419, 421, 453

(3) Millets : Hybrid maize (Ganga-3), Jowar (CO-12) and Bajra (Niphad) : High yielding and resistant to water stress.

8. Plant Breeding for Disease Resistance :

• Its objective is to develop varieties that are resistant to plant pathogens.
• It is carried out by hybridization process.
• Some of the plant diseases are as follows.
  

  Plant pathogens	Diseases
  Viruses	Tobacco mosaic disease Chilli mosaic disease
  Fungi	Brown rust of wheat Late blight of potato Red rot of sugar cane Smut of wheat
  Bacteria	Black rot of crucifers

• Disease resistant varieties of different crops :
  

  Disease resistant varieties	Diseases
  Pusa sadabahar of chilli	Chilli mosaic virus, Tobacco mosaic virus and leaf curl
  Pusa shubhra of cauliflower	Black rot and curl blight black rot
  Himgiri variety of wheat	Hill bunt Leaf and stripe rusy
  Pusa swarnim of Brassica	White rust

B. Mutation Breeding :

• Mutation : It is a sudden heritable change in the genotype, caused naturally.
• Natural (physical) mutagens : High temperature, high concentration of C02, X-rays, UV rays.
• Chemical mutagens : Nitrous acid, EMS (Ethyl – Methyl – Sulphonate), Mustard gas, Colchicine, etc.
• Effects of mutagens : Gene mutations and chromosomal aberrations.
• Seedlings or seeds are irradiated by Cobalt 60 or they are exposed to UV bulbs, X-ray machines, etc. The treated seedlings are then screened for resistance to diseases/ pests, high yield, etc.

Mutant varieties :

• Rice : Jagannath
• Wheat : NP 836 (rust resistant)
• Cotton : Indore-2 (resistant to bollworm)
• Cabbage : Regina-II (resistant to bacterial rot), etc.

C. Plant Breeding for Developing a Resistance to Insect Pest :

1. Resistance due to morphological characters :

• Hairy leaves in cotton : Vector resistance from jassids.
• Hairy leaves in wheat : Vector resistance from cereal leaf beetle.
• Solid stem in wheat : Resistance to stem borers.

2. Resistance due to biochemical characters :

• The high aspartic acid and low nitrogen and sugar content in maize : Resistance against stem borers.
• The nectar-less cotton having smooth leaves : Resistance against bollworms.

3. Some pest resistant varieties:

Insect resistant varieties of various crops	Insect pests
Pusa Sawani, Pusa A-4 of Okra (Bhindi)	Fruit and shoot borer
Pusa Gaurav of Brassica	Aphids
Pusa Sem 2 and Pusa Sem 3 of Flat bean	Jassids, aphids and fruit borers

Tissue culture

1. Tissue culture : It is growing isolated cells, tissues, organs ‘in vitro’ on a solid or liquid nutrient medium, under aseptic, controlled conditions of light, humidity and temperature, for achieving different objectives.
2. Explant : The part of plant used in tissue culture.
3. Totipotency : An inherent ability of living plant cell to grow, divide, redivide and give rise to a whole plant.
4. Haberlandt (1902) : He gave concept of in vitro cell culture (plant morphogenesis).
5. The plant tissue culture medium : It consists of all essential minerals, sources for carbohydrates, proteins and fats, water, growth hormones, vitamins and agar (for callus culture).
6. The most preferred medium for tissue culture : MS (Murashige and Skoog) medium.

7. Types of tissue culture :

• Based on the nature of explant : Cell culture, organ culture and embryo culture.
• Based on the type of in vitro growth : Callus culture (solid medium is used) and Suspension culture (liquid medium is used).

8. Requirements of tissue culture :

(1) Maintenance of aseptic conditions :

• Sterilization of glassware : It is carried out using detergents, hot air oven.
• Sterilization of nutrient medium : It is done by using autoclave.
• Sterilization of explant : It is carried out by treatment of 20% ethyl alcohol and 0.1% HgCl₂.
• Sterilization of inoculation chamber (Laminar air flow) : It is carried out by using UV ray tube for 1 hour before performing actual inoculation of explant on the sterilized nutrient medium.

(2) Temperature : 18 °C to 20 °C
(3) pH of nutrient medium : 5 to 5.8
(4) Aeration (particularly for suspension culture)

9. Steps in tissue culture : They are as given in the chart.

• Cleaning and sterilization of glassware and instruments in an autoclave or oven
• Preparation of defined nutrient medium . (MS medium)
• Sterilization of nutritive medium in an autoclave
• (For 20 minutes under constant pressure of 15/lb/inch²)
• Isolation and surface sterilization of explant
• Inoculation of the explant in the culture flask containing sterilized nutrient medium.
  (Inoculation is done in the laminar air flow cabinet unit) Incubation of the inoculated explant
  (cells of explant divide and give rise to callus, within 2-3 weeks)
• Sub culturing of the callus (Division of callus into 3-4 parts which are transferred to fresh culture medium)
• Organogenesis (Initiation of rooting and shooting)
• Plantlet formation
• Hardening of plantlets (Plantlets are transferred to polythene bags containing sterilized soil and kept at low light and high humid conditions for appropriate time period)
• Hardened plantlets are transferred to field

10. Sub culturing : Both the callus and suspension cultures die in due course of time. Therefore, sub culturing is necessary for continuation of the technique. In this a part of callus or suspension culture is transferred to fresh medium.

11. Micropropagation (Clonal Propagation) :

1. It is a type of tissue culture technique by which large number of plants are regenerated using organogenesis.

2. It is used in commercial production of plants like orchids, Chrysanthemum, Eucalyptus, banana, grapes, citrus, etc.

3. Advantages of micropropagation :

• Rapid multiplication of large number of plants within a short period and from a small space.
• Plants are obtained throughout the year, independent of seasons.
• Desirable characters (genotype) and desired sex of superior variety can be maintained for several generations.
• Conservation of rare plant and endangered species.
• Somatic hybrids (cybrids) can be used to develop new variety in short time span.
• High yielding varieties of banana like Shrimati, Basarai and G – 9 are used in Maharashtra.

12. Applications of tissue culture :

• Production of disease free plants and haploid plantlets.
• Production of stress resistant plants, micropropagation.
• Protoplast culture.
• Production of secondary metabolites.
• Culture of rare plants.
• Somaclonal variations.
• Application of tissue culture in forestry, agriculture, horticulture, genetic engineering and physiology.

Single cell protein (SCP)-

1. Conventional method to increase food yield : Use of different methods of crop improvement, biofertilizers, biopesticides, chemical fertilizers and high yielding varieties.
2. Nonconventional methods to increase the
food yield : Use of SCP .
3. , SCP is required to meet growing demand for
protein and to avoid protein malnutrition.
4. Single cell protein : It is a crude or a refined edible protein, extracted from pure microbial cultures or from dead or dried cell biomass.
5. Substrates used for the production of SCP : Wood shavings, sawdust, corn cobs, paraffin, N-alkanes, sugar cane molasses, human and animal wastes.
6. The microorganisms used for the production of SCP :

• Fungi : Aspergillus niger, Trichoderma viride
• Yeast : Saccharomyces cerevisiae, Candida utilis
• Algae : Spirulinaspp, Chlorella pyrenoidosa
• Bacteria : Methylophilusmethylotrophus, Bacillus megasterium

7. Advantages of Single Cell Protein :

• Microbes multiply fast. Hence, a large quantity of biomass can be produced in a short duration.
• The microbes can be easily genetically modified to vary the amino acid composition.
• SCP is a rich source of proteins (43% to 85% WAV basis), vitamins, amino acids, minerals and crude fibres.
• As waste materials are used as a substrate for SCP there is less pollution.

i. e. SCP can be used as fodder for achieving fattening of calves, pigs, in breeding fish, in poultry and cattle farmimg.

Biofortification-

1. Biofortification is a method of developing crops for having higher quantity and quality of vitamins, minerals and fats, to overcome problem of malnutrition.
2. Objectives of biofortification :

• Improvement in protein content and quality
• Improvement in oil content and quality
• Improvement in vitamin content
• Improvement in micronutrient content and quality

3. Methods of development of biofortified varieties : Conventional selective – breeding practices and r-DNA technology.

4. Some examples of biofortification :

• Fortified Maize (Twice the amount of amino acids – lysine and tryptophan)
• Wheat – Atlas 66 (High protein content)
• Rice (Has 5 times more iron)
• Carrot and spinach (Enriched with vitamin A and minerals)
• Bittergourd, tomato (Enriched with vitamin C enriched, developed by IARI)
• Animal husbandry-

1. Animal husbandry is an agricultural practice of breeding and raising livestock.
2. It deals with care and breeding of livestock like buffaloes, cows, pigs, horses, cattle, sheep, camels, goats, etc. which are useful to : humans.
3. Products obtained from animals : Milk, eggs, meat, wool, honey, silk, etc.
4. The production can be increased by –

• Effective management procedures
• New technologies in various farm systems to j improve quality and productivity
• Use of industrial principles of production processing and marketing

5. Management of farms includes selection of high yielding breeds, taking care of food requirements, supply of adequate nutritional sources, cleanliness of the environment and maintenance of health.

6. Management of farm animals includes veterinary supervision, vaccination, high yielding cross breed development, production and preservation of products, distribution and marketing.

A. Animal breeding :

1. Aims of animal breeding :

(1) To increase the yield of animals.
(2) To improve the desirable qualities of the products.
(3) To develop breeds with desirable characters.

2. Breed : A group of animals related by descent and similar in most characters like general appearance, features, size, configuration, etc.

3. Types of breeding :

(1) Inbreeding : Mating of two closely related individuals within the same breed for 4 to 6 generations.
(2) Outbreeding : Breeding of unrelated animals. It is of following types :

• Outcrossing : Mating of animals within the same breed, but having no common ancestors on either side of mating partners up to 4-6 generations is called outcrossing. [Mote : Outcrossing is not same as interspecific hybridization. ]
• Cross-breeding : Cross-breeding is a practice in which superior males of one breed are mated with superior females of another breed.
• Interspecific hybridization : Mating between male and female animals of two different related species, e.g., interspecific hybridization between horse and donkey produces a mule.

4. Artificial insemination : Used for controlled breeding experiments. Semen from the superior male is collected and injected into the genital tract of the female.

5. Multiple Ovulation Embryo Transfer (MOET) : MOET provides chances of successful production of hybrids.

B. Dairy farm management:

1. Dairy industry: It involves production, processing, marketing and distribution of milk and various milk products. Cow dung, manure, fuel cakes and gobar gas (for cooking and lighting) are sources of additional income.
2.  Breeds of cows :
   • Indian breeds of cows : Sahiwal, Sindhi, Gir”
   • Exotic breeds of cows : Jersey, Brown Swiss, Holstein.
3.  Breeds of buffaloes in India : Jaffarabadi, Mehsana, Murrah, Nagpuri, Nlli, Surati.
4. Cattle feed : Silage, oilcakes, minerals, vitamins and salts.
5. The cattle shed : It must be clean, spacious with adequate facilities for feeding, watering and lighting.
6. Cleanliness and hygiene of the cattle and handlers is important during milking, storage and transport of milk and milk products.
7. Mechanization of these reduces the chance of direct contact with the product.
8. Daily visit of veterinary doctor to dairy farm is mandatory to diagnose health problems, diseases and for their rectification.

C. Poultry farm management:

1. Poultry : It includes chicken, ducks, turkey, and fowls which are domesticated for their eggs and meat.
2. Allied professions to poultry : Processing of eggs and meat, marketing of poultry products, compounding and sale of poultry feed, poultry equipment, pharmaceuticals, feed additives, etc.
3. Requirements for poultry farm Management:
Selection of proper and disease free breed, suitable and safe farm condition, proper feed and water, hygiene and health care.

4. Poultry breeds (On the basis of their origin) :

• American breeds : Plymouth Rock, New Hampshire, Rhode Island Red
• Asiatic breeds : Brahma, Cochin and Langshan
• Mediterranean breeds : Leg horn, Minorca
• English breed : Australorp
• Indian breeds : Chittagong, Aseel, Brahma and Kadaknath.

5. Best layer (for eggs) : Leghorn.
6. Best broilers (for meat) : Plymouth rock, Rhode Island Red, Aseel, Brahma and Kadaknath.
7. Management of layers : It involves purchase of high yielding chicken, well-ventilated farms, proper feed, debeaking, lighting, waterer, sanitation, culling and vaccination.
8. Management of broilers : It involves selection of breed, housing, temperature, ventilation, lighting, floor space and broiler feed.

9. Poultry diseases :

• Viral diseases : Ranikhet, Bronchitis, Avian influenza (bird flu), etc. Bird flu had serious impact on poultry farming and also caused infection to humans.
• Bacterial diseases : Pullorum, Cholera, Typhoid, TB, CRD (chronic respiratory disease), Enteritis, etc.
• Fungal diseases : Aspergillosis, Favus and Thrush.
• Parasitic diseases : Lice infection, round worm, caecal worm infections, etc.
• Protozoan diseases : Coccidiosis.

D. Apiculture or bee keeping :

• Apiculture is artificial rearing of the honey bees.
• Products obtained by apiculture : Honey, wax, pollen, bee venom and royal jelly.
• Honey bees are important pollinators for crop plants and fruit trees.
• Apis dorsata (Rock bee or wild bee), Apis melltfera (European bee), Apis indica (Indian bee), Apis Jlorea (Little bee) are the four commonly occurring species in India.
• Apis mellifera and Apis indica are the : suitable species for apiculture and hence Eire : called domesticated species.
• Equipment required for apiculture: It includes beehive boxes, comb foundation sheets, bee veil, smoker, bee brush, gloves, gumshoes, uncapping knife, swarm net, queen : excluder, overall hive tool, etc.
• Successful apicultures also requires familiarity with the habits of bees, selection of suitable location, catching and hiving of swarms, management of hives during different seasons, handling and collection of honey, bee wax and other products, periodic inspection for cleanliness of hive boxes, activity of bees and queen, condition of brood, provision of water.
• Pollination of variety of crop plants by honey bees increases the productivity of honey and crop.

E. Fishery:

• Catching, processing, fish farming and marketing of the fish and other edible aquatic organisms is called fishery.
• Some fishes, prawns, lobsters, oysters, mussels, crabs, etc. are commercially important varieties.
• Inland fishery, estuarine fishery and marine fishery are the three main types of fisheries.
• A long coastline of India of about 7500 km and 40 to 50 lakh acres of fresh water bodies together constitute fishery potential.
• Common fresh water fishes, Rohu, Catla, Mrigal, common carp, grass carp, silver carp, etc. while marine fishes such as Hilsa, Bombayduck, sardines, pomphrets, mackerel, etc. are important varieties of fish.
• Fish farming is another occupation related to fishery in which culturing of some varieties of fish is done. Monoculture and polyculture are two main methods of aquaculture.
• Maintenance of fish farm : It involves selection of suitable site, excavation of ponds, requirements of hatchery tank, nursery tank rearing tank, stocking tank or ponds, water source, manures, supplementary feed, etc.
• Fish farming or culturing of commercially important edible fishes is only possible in fresh water bodies.
• Fish spoilage is prevented by preservation methods such as chilling, freezing, freeze drying, sun-drying, salting, canning, etc.
• Fish oil, fish meal, fertilizers, fish guano fish glue and Isinglass are some of the by-products made from the fish.

F. Sericulture:

• Rearing and production of silkworm (Bombyx mori) for obtaining silk is sericulture.
• Types of silk fibres : Mulberry silk, Tussar silk and Eri silk. Best quality mulberry silk is produced by Bombyx mori.

G. Lac culture :

• Tacchardia lacca insect produces lac. Lac is the resinous substance produced by dermal glands of the female insect.
• Plants such as her, peepal, palas, kusum, babool, etc. form the feed of these insects.
• 85% of lac produced in the world is from India.
• Various articles such as bangles, toys, woodwork, polish inks, silvering of mirrors, etc. are produced from lac.
• Artificial inoculation of plants give better and regular supply of lac.

Microbes in human welfare-

1. Biotechnology : It is defined as applications of ‘Scientific and Engineering principles for the processing of materials by biological agents to provide goods and service to humans or for human welfare’.

2. Microbes in food preparation :

1. Lactobacilli : Dhokla
2. Leuconostoc and Streptococcus bacteria : Dosa and idlis.
3. Microbes as the source of food : e.g. SCR fleshy fruiting bodies of edible mushrooms and truffles (higher fungi).

Dairy Products :

• Curd : Lactobacillus acidophilus
• Yoghurt : Streptococcus thermophilus and Lactobacillus bulgaricus
• Buttermilk : It is the acidulated liquid left after churning of butter from curd.
• Cheese : The milk is coagulated with LAB. The curd formed is filtered to separate whey and the solid mass is then ripened with growth of mould that develops flavour in it.
  • ‘Roquefort cheese : Ripened by blue- green mold Penicillium roquefortii
  • Camembert cheese : Ripened by blue- green mold Penicillium camembertii
  • Swiss cheese : Ripened by Propionibacterium shermanii. The large holes in Swiss cheese are developed due to production of a large amount of CO₂

Role of Microbes in Industrial Production-

Useful products produced during fermentation : Alcoholic beverages, organic acids, vitamins, growth hormones, enzymes, antibiotics and other molecules of medical significance are produced.

Statins produced by yeast Monascus purpureus are blood cholesterol lowering agents. They are competitive inhibitors of the enzyme that catalyzes synthesis of cholesterol.

1. Production of alcoholic beverages :

• Alcoholic beverages are produced by fermentation : liquors like beer, Whisky and wine.
• Saccharomyces cerevisiae var. ellipsoidis (Brewer’s Yeast) is used for fermenting malted cereals and fruit juices to produce ethanol.
• The beverages produced without distillation : Wine and Beer
• The beverages produced with distillation : Whisky, brandy and rum

Traditional drinks :
a. Toddy : Made by fermenting the sugar sap extracted from palm plants and coconut palm.
b. Fenny : Made by fermenting fleshy pedicels of cashew fruits.

2. Production of organic acids :
Microbes are used in the production of a number of organic acids.

• Aspergillus niger – Citric acid
• Aspergillus niger – Gluconic acid
• Rhizopus arrhizus – Fumaric acid
• Acetobacter aceti – Acetic acid (vinegar)

3. Production of vitamins :

(1) Vitamins : Organic nitrogenous compounds capable of performing many life-sustaining functions inside our body.
(2) Examples of vitamins : Thiamine, riboflavin, pyridoxine, folic acid, pantothenic acid, biotin, vitamin B₁₂, ascorbic acid, beta-carotene (provitamin A) and ergosterol (provitamin D).
(3) Vitamins are manufactured by fermentation using different microbial sources :

• Vitamin B₂ – i. Neurospora gossypii
  ii. Eremothecium ashbyi
• Vitamin B₁₂ – Pseudomonas denitrificans
• Vitamin C – Aspergillus niger

4. Production of Antibiotics :

(1) Antibiotics are secondary metabolites produced in small amounts by certain microbes (like bacteria, fungi and few algae), which inhibit growth of other microbial pathogens.
(2) They are used in treatment of deadly diseases like plague, whooping cough, diphtheria, leprosy, etc.
(3) Some common antibiotics and their microbial sources are as follows :
(4) Different antibiotics produced from following microbes:

• Chloromycetin → Streptomyces venezuelae
• Erythromycin → Streptomyces erythreus
• Penicillin → Penicillium chrysogenum
• Streptomycin → Streptomyces griseus
• Griseofulvin → Penicillium griseofulvum
• Bacitracin → Bacillus lichenijormis
• Oxytetracycline, Terramycin → Streptomyces aurifaciens

5. Production of Enzymes :

(1) Enzymes : Enzymes are biocatalyst proteins which accelerate biochemical processes.
(2) Uses of enzymes in various industries :

• Textile industry : To improve the quality of the fabrics.
• Pulp and paper industry : Biomechanical pulping and bleaching.
• Food industry : Fermentation for the production of bread and drinks such as wine and beer,
• Detergent industry : Lipase is used because of superior cleaning properties, to increase the brightness and to remove oil stains.
• The extraction of substances like carotenoids and olive oil.
• Enzymes are also used in cosmetics, animal feed and agricultural industries, among others.
• Streptokinase has fibrinolytic effect. Hence, it is used as a ‘clot buster’ in blood vessels of heart patients.

(3) Examples of microbial sources from which enzymes are produced :

• Saccharomyces cerevisiae – Invertase
• Sclerotinia libertine, Aspergillus niger – Pectinase
• Candida lipolytica – Lipase
• Trichoderma konigii – Cellulase
• Streptococcus spp. – Streptokinase

6. Gibberellin production :

(1) Gibberellin is a growth hormone produced by higher plants and a fungus named Giberella.
(2) Practical applications :

• To induce parthenocarpy in apple, pear, etc.
• Used in breaking the dormancy of seed and also in inducing flowering in Long Day Plants (LDP).
• To enlarge the size of grape fruits.

Microbes in Sewage Treatment –

1. Composition of Sewage carried out in drainage :

• Sewage consists of about water (99.5% to 99.9%) and inorganic and organic matter (0.1 to 0.5%) in suspended and soluble form.
• Composition of sewage varies depending upon the type of waste discharged into water from different industries.
• It includes human excreta, household waste, dissolved organic matter and even pathogenic microbes, discharged water from hospital waste, slaughter house waste, animal dung, discharge from industriad waste (contains toxic dissolved organic and inorganic chemicals), tannery, pharmaceutical waste, etc. also add to sewage.
• It contains bacteria from soil and pathogenic microorganisms (bacteria, viruses and protozoa) causing dysentery, cholera, typhoid, polio and infectious hepatitis and soil bacteria.
• Bacteria in sewage include coliforms, fecal Streptococci, anaerobic spore forming Bacilli and other types originating in the intestinal tract of humans.

2. Sewage treatment process includes four basic steps:

• Prelinfinary Treatment: It Includes Screening and Grit Chamber.
• Primary treatment (physical treatment) : It involves treatment of sewage in primary sedimentation tanks.
• Secondary treatment (biological treatment): It includes treatment of sewage in aeration tanks.
• Tertiary treatment : It involves passage of sewage water through settling tank and anaerobic sludge digesters.

Microbes in Energy Generation-

1. Biogas is a mixture of methane CH₄ (50-60%), CO₂ (30-40%), H₂S (0-3%) and other gases (CO, N₂, H₂) in traces.

2. Substrates used for biogas production : Cattle dung (most commonly used substrate, a rich source of cellulose from plants), plant wastes, animal wastes, domestic wastes, agriculture waste, municipal wastes, forestry wastes, etc.

3. Biogas Production :

• Most commonly used models of biogas plants are developed by KVIC (Khadi and Village Industries Commission) and IARI (Indian Agricultural Research Institute).
• A typical biogas plant consists of digester and gas holder.
• Anaerobic digestion involves three processes : Hydrolysis or solublization, acidogenesis and methanogenesis.

4. Benefits of biogas :

• Biogas is a cheap, safe and renewable source of energy.
• It can be easily generated, stored and transported.
• It can be used for domestic lighting, cooking, street lighting as well as small scale industries.
• It burns with blue flame and without smoke.
• It helps to improve sanitation of the surrounding.
• It is eco-friendly and does not cause pollution.
• Sludge which is left over is used as a fertilizer.

Role of Microbes as Biocontrol Agents-

1. Biocontrol or biological control : It is the natural method of eliminating and controlling insects, pests and other disease-causing agents by using their natural, biological enemies.

2. Biocontrol agents : Microbes (bacteria, fungi, viruses and protozoans) act as biocontrol agents in three ways : they cause the disease to the pest or compete or kill them.

3. Some examples of Microbial bio-control :

• Bacillus thuringiensis (Bt) : It is used to get rid of butterfly, caterpillars.
• Trichoderma species : Effective bio-control agents against soil borne fungal plant pathogens.

4. Microbial Pesticides and their host:

Host	Microbial pesticide
Caterpillars, Gypsy moth, ants, wasps, beetles	Viruses : Nucleopolyhedrovirus (NPV) Granulovirus (GV)
Caterpillars, cabbage worms, adult beetle	Bacteria : Bacillus thuringiensis (Bt) B. lentimorhus B. papilliae
Aphid crocci, A. unguiculata, mealy bugs, mites, white flies	Fungi : Beavueria bassiana Entomorphtora pallidaroseum Zoopthora radicans
Grasshoppers, caterpillars, crickets	Protozoans : Nosema locustae

5. Bioherbicides : They kill the weeds which compete with the main crop in the farm – land for water, space, minerals, light, air, etc. and also act as collateral hosts for several pathogens.
(1) Pathogenic fungi as mycoherbicides :

• Phytophthora palmivora – controls milk weed in orchards.
• Alternaria crassa – controls water hyacinth.
• Fusarium spp. – control most of the weeds.

(2) Bacterial pathogen as herbicides :

• Pseudomonas spp. – attacks several weeds
• Xanthomonas spp. – attacks several weeds
• Agrobacterium spp. – attacks several weeds

(3) Insects as herbicides :

•  Tyrea moth – controls the weed Senecio jacobeac
• Cactoblastis cactorum – controls cacti weeds.

Role of Microbes as Biofertilizers-

1. Fertilizers are the nutrients required for plant growth and increase the productivity of cultivated plants.
2. Types of fertilizers :

• Inorganic fertilizers : They are synthetic fertilizers consisting of mineral salts of NPK mixed in specific proportion. If used excessively, they cause pollution of soil, air and groundwater.
• Organic fertilizers : They are biological in origin and include farm yard manure (FYM), compost and green manure.

3. For better and sustainable agricultural production, organic farming is practised and biofertilizers are used.

4. Biofertilizers include bacterial, cyanobacteria and fungi :

• Bacterial biofertilizers : These include bacteria and cyanobacteria
• Fungal biofertilizers

5. Types of Biofertilizers on the basis of nature and function :

(1) N₂ fixing Biofertilizers :

• The nitrogen fixing microorganisms (diazotrophs) convert atmospheric nitrogen into nitrogenous compounds like nitrites and nitrates via ammonia.
• Symbiotic N₂ fixing microorganisms : e.g. Rhizobium, Frankia.
  These are mostly associated generally with roots of higher plants.
• Free-living or Non-Symbiotic N2 fixing microorganisms : e.g. Azotobacter, Clostridium, Beijerinkia, Klebsiella, etc.

(2) Phosphate solubilizing biofertilizers :

• These bacteria solubilize the insoluble inorganic phosphate compounds.
• e.g. Pseudomonas striata, Bacillus polymgxa, Agrobacterium, Microccocus, Aspergillus spp. etc.

(3) Compost making biofertilizers :

• In the composting process microorganisms break down organic matter into dark rich compost or humus.
• Microorganisms found in active compost: Bacteria, fungi, actinobacteria, protozoa and rotifers.

6. Cyanobacteria as biofertilizers :

• They may be free-living or symbiotic, heterocystous or non-heterocystous forms.
• Free living cyanobacteria : e.g. Anabaena, Nostoc, Plectonema, Oscillatoria.
• Symbiotic cyanobacteria associated with lichens : Anabaena, Nostoc and Tolypothrix.
• Symbiotic cyanobacteria associated with plants Azolla and Cycas : Anabaena.

7. Fungal biofertilizers :

(1) Mycorrhiza is a fungus which forms symbiotic association with the rhizomes and root of higher plants occurring in thick humid forests.

(2) Two types of mycorrhizal :

• Ectomycorrhizae : Mycelium of these fungi form mantle on the surface of the roots.
• Endomycorrhizae : They grow in between and within the cortical cells of roots.

(3) Benefits of Mycorrhiza :

• Selective absorption of P Zn, Cu, Ca, N, Mn, Br and Fe.
• Enhance water uptake.
• Induce growth by secreting hormones.
• Offer protection to host plant from other microbes, by secreting antibiotics.

(4) Nowadays, mycorrhiza are classified into 8 different types : Ectomycorrhizae,

Endomycorrhizae, Ectendo mycorrhizae, Orchidaceous mycorrhizae, Ericoid mycorrhizae, Arbutoid mycorrhizae, Monotrapoid mycorrhizae and Ophioglossoid mycorrhizae.

8. Biofertilizer microorganisms :

• Rhizobia : Nitrogen fixing bacteria in root nodules of leguminous plants.
  e. g. R. leguminosarum is specific to pea and R. phaseoli is specific to beans.
• Azotobacter: Free living, nitrogen fixing bacterium associated with roots of grasses and certain plants.
• Azospirillum: Free living, aerobic nitrogen fixing bacterium associated with roots of corn, wheat and jowar.
• Anabaena : Filamentous nitrogen fixing cyanobacteria that forms symbiotic relationships with certain plants, such as the coralloid roots of Cycas and Anthoceros thallus. It has Heterocysts (Specialized colourless cells which are the sites for nitrogen fixation). It also fixes nitrogen in free living conditions.
• Azolla : A free-floating water fern. Anabaena present in the dorsal leaf lobe fixes nitrogen.

9. Benefits of Biofertilizers :

• Low cost and can be used by marginal farmers.
• Free from pollution hazards.
• Increase soil fertility.
• BGA secret growth promoting substances, organic acids, proteins and vitamins.
• Azotobacter supply nitrogen and antibiotics in the soil.
• Biofertilizers increase physico-chemical properties of soil-like texture, structure, pH, water holding capacity of soil by providing nutrients and organic matter.

Know the Scientist:

1. Dr. Norman E. Borlaug : Known as ‘Father of the Green Revolution’, ‘Agriculture’s greatest spokesperson’ and ‘The Man Who Saved a Billion Lives’.
A 1970 Nobel Laureate.
He saved millions of lives from famine in India, Mexico and the Middle East.

2. Dr. M. S. Swaminathan : Known as ‘Father of Green Revolution in India’.
He introduced and developed high-yielding varieties of wheat in India.
He is pioneer in mutation breeding in India.
He developed new varieties of wheat like Sarbati, Sonora and NP165.
He advocated environmentally sustainable agriculture, sustainable food security and the preservation of biodiversity.

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 6 Plant Water Relation students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 6 Plant Water Relation

Introduction-

1. Types of substances required by the plant from its surroundings

• Water
• Minerals
• Nutrients
• Food (for parasites)
• Gases from the atmosphere : (A) O₂ for respiration (B) CO₂ for photosynthesis

2. Water is absolutely necessary for all vital activities. Hence referred to as elixir of life.
3. Role of water :

• Major constituent of protoplasm (90-95%)
• Helps in maintaining the turgidity of cells and their shape.
• It is a transporting medium.
• Water affects productivity of plants.

Properties of water-

1. Important properties of water.

• Liquid form at room temperature.
• Best solvent for various solutes.
• Inert inorganic compound.
• Neutral pH (i.e. pH = 7) of pure water.
• High specific heat.
• High heat of vaporization.
• High heat of fusion.

2. Due to these properties water is best transporting medium, best medium for biochemical reactions and acts as a thermal buffer.
3. Hydrogen bonding occurs in liquid water which is mainly responsible for these properties.
4. Good adhesive and cohesive forces exist in water molecule.
5. Owing to high surface tension and these forces, it can rise in capillaries.
6. Water is a molecule that connects or is a link between physical factors and biological processes.

Water absorbing organ-

1. Root system – Chief organ of water and mineral absorption.
2. Terrestrial plants absorb liquid water from soil with root hairs while epiphytes like orchids, have special hygroscopic tissue velamen that absorbs water vapour from atmosphere.
3. Regions of root – four zones.
Root cap is situated at tip behind it is

• zone of meristematic region
• zone of elongation
• zone of absorption or root hair zone and
• zone of maturation.

4. In zone of absorption, thin, delicate, unicellular hair like extensions i.e. root hairs develop from epidermal cells.
5. Structure of root hair : It is cytoplasmic extension, tube like, colourless, unbranched and short lived (ephemeral) structure.
6. Root hair has large central vacuole, thin cytoplasm, plasma membrane and double layered wall of pectin and cellulose.
7. Freely permeable cell wall while selectively permeable plasma membrane.

Water available to roots for absorption-

1. Rhizosphere : Microenvironment surrounding the root, constitutes rhizosphere from which plants absorb water.
2. Soil is the main source of water for plants.
3. Water present in soil is in following forms namely :

• Gravitational water percolated deep in soil due to gravity.
• Hygroscopic water held tightly around soil particles, adsorbed or adhered water on fine particles.
• Combined water present as hydrated oxides of silicon, aluminium, etc.
• Capillary water present in the fine spaces or capillaries between soil particles.

4. Plants readily absorb capillary water from soil.

Absorption of water by roots from soil-

When water is absorbed by plant, all the three physical processes occur simultaneously at root hair.

1. Imbibition :

• Swelling up of hydrophilic colloidal substances.
• Water is adsorbed on the surface.
• Imbibant : Substance that adsorbs.
• Imbibate : Substance that gets imbibed.
• In root hair double layered cell wall of cellulose and pectin is imbibant.
• Water is tightly adsorbed on the surface till the equilibrium is reached.

2. Diffusion :

• Movement of ions/atoms/molecules of a substance from region of high concentration to that of their low concentration.
• Movement results due to kinetic energy.
• It takes place till equilibrium is reached.
• In root cell, diffusion occurs through freely permeable cell wall.
• Diffusion pressure created is directly proportional to number of diffusion particles.
• Pure water has more diffusion pressure (D.E) than solvent in solution.
  Diffusion results in diffusion pressure. D.ED. can be considered as thirst of cell, capacity which absorbs water from surrounding of adjacent cell.
• D.ED. (Diffusion Fressure Deficit = S.E (Suction Fressure)
• Difference in D.E of pure solvent (i.e. water) and solvent in solution is termed D.ED.
• D.ED. is capacity to absorb water from surrounding.
• Cell sap has less D.E than water around cell wall. Thus, water diffuses inside.
• It is significant in absorption of water and minerals, transport of food, exchange of gases and conduction of water upwards against gravity.

3. Osmosis :

•  A process by which water actually enters root hair (cell interior).
• Special type of diffusion.
• Involves movement of solvent through a semipermeable membrane.
• Cell sap inside the cell is concentrated (minerals, sugars) while solution outside cell is weaker. Hence solvent (water) from outside enters the cell passing through semipermeable plasma membrane.
• In root cell, at interphase of cell wall and plasma membrane, water enters by osmosis.
• Type of solutions based on concentration
  
• Two types of osmosis
  
• Turgor pressure (T.P.) : Pressure exerted by turgid cell sap on cell membrane and cell wall.
• Fully turgid cell has D.ED. = 0 (zero)
• Wall pressure (W.P.) : Cell wall exerts pressure on inner cell sap i.e. counterpressure. Hence T.P = W.P but it is in opposite direction.
• Osmotic pressure (O.P.) : Pressure exerted due to osmosis so as to stop entry of water (solvent) inside.
  • Pressure of solution in opposite direction.
  • To check entry of water (solvent molecules) inside cell.
• D.RD. (thirst of cell) demand or ability to gain water by cell = O.P – T.P and T.P = W.P
  ∴ D.ED. = O.P – W.P (Osmotic pressure minus wall pressure)
• In flaccid cell T.P is 0 (zero) . .D.RD. = O.E In turgid cell D.PD. is 0 (zero) ..T.R = O.R

Facilitated diffusion :

• Passive absorption of solutes (no expenditure of energy)
• Takes place with the help of carriers (special proteins – porins)
• Diffusion through cell membrane
• Lipid soluble components can easily pass but hydrophilic components need carrier.
• Requirement of concentration gradient for diffusion.

Membrane proteins – aquaporins and ion channels are sites of facilitated diffusion.

Water potential ( Ψ )-

• Free energy is needed to do the work and for movement of water, i.e. osmosis )
• Chemical potential : Free energy per molecule in a chemical system.
  Water potential : It is chemical potential of water – Unit bars / pascal (pa) / atmosphere D.RD. is now termed as water potential.
• Water potential of protoplasm is opposite in sign but equal to D.RD. i.e. negative value.
• Pure water has water potential zero. When some solute is added there is decrease in water potential (t//) i.e. negative.
• Flow of water is from less negative potential to more negative potential, i.e. from higher water potential to lower.
• In adjacent cells, plasmodesmata connections are concerned with movement of water.

Factors affecting water absorption :

• Types of water-presence of capillary water.
• Soil temperature-favourable range 20 to 30°C.
• Concentration of solutes in soil water – High solute concentration reduces rate of absorption.
• Soil aeration : If soil aeration is less then there is absorption.
• Rate of transpiration : With increase in transpiration, there is increase in absorption of water.

Plasmolysis-

1. Exosmosis that occurs in living cells upon placing in hypertonic (concentrated) solution is termed plasmolysis.

• Shrinkage of protoplasm
• Separation from cell wall forms a gap between cell wall
• Flaccid nature due to removal of water.

2. Turgor pressure (T.R) is zero in plasmolysed cell.
3. Deplasmolysis : When flaccid cell is kept in hypotonic solution endoosmosis takes place and thus it becomes turgid.
4. In fully turgid cell T.R = O.P and D.RD. is zero, (no absorption of water by cell)

Path of water across the root (i.e. from epiblema up to xylem in the stelar region)-

1. Root hair cell : Absorption of water takes place from rhizosphere by process of imbibition then diffusion and finally osmosis.

2. In turgid cells (root hair) due to absorption of water → Increased turgor pressure (T.P) and lowered D.PD. →adjacent cell (Cortical cell) → more D.PD. more osmotic pressure (O.R) → adjacent cell will take water from turgid root ha.i → root hair cell thus becomes flaccid → absorb water from soil.

3. A gradient of D.PD. or suction pressure (S.R) is formed from root epidermis till the region of cortical cells.

4. Movement of water is from root hair → epidermis → loosely arranged cortical cell → passage cells of endodermis → pericycle → protoxylem

5. Due to continuous absorption of water hydrostatic pressure is developed, i.e. root pressure → Helps in transfer and conduction further in xylem of root.

6. The movement of water from root hair to xylem takes place along two different pathways, viz. apoplast pathway and symplast pathway.

7. Pathway for water across roots:

8. Additional apoplast pathway :

• Direct pathway leading to xylem.
• Secondary roots originate at pericycle inside endodermis.
• Bypass endodermis having Casparian strip. Hence allow direct entry in vascular system.

9. In normal apoplast pathway, suberised layer forces shift to symplast in order to enter xylem.

10. Symplast pathway is transmembrane pathway through plasmodesmatal connections in living cells of cortex. The plasmodesmata interconnect the cytoplasm of cells forming cytoplasmic network called symplast.

Learn this as well :

• Vacuoles in the root cells are interconnected to form intercellular connections.
• Intervacuolar connections are formed between the cells.
• Cytoplasmic connections are towards the periphery of cell.
• Tonoplast, the membrane of vacuole is differentially permeable membrane which allows the passage of certain solutes but not all along with solvent.

Mechanism of absorption of water-

Translocation of water-

1. Ascent of sap : Transport of water along with dissolved minerals from root to aerial part against gravity is called translocation or ascent of sap.
2. Ascent of sap occurs through lumen of xylem tracheids and vessels. Physical forces and activity of living cells is required for ascent of sap. Complex tissue xylem as a path of water is proved by ringing experiment.
3. Root pressure theory (Vital theory) by J. Pristley :

• Living cells of root are responsible for translocation of water.
• Xylem sap exuding out from cut end of stem above the soil indicates existence of root pressure.
• As water is absorbed by root hair constantly and continuously, hydrostatic pressure is set in root cortical cells.
• Owing to this root pressure, water with dissolved minerals is pushed into xylem and also conducted upwards.
• Root pressure is an osmotic phenomenon, develops due to absorption of water.
• Oxygen, moisture, temperature and salt content of soil affect root pressure, Root pressure of +1 to +2 bars is sufficient to carry water upwards to 10 to 20 metres.

Objection to this theory :

• Not applicable to tall plants.
• Ascent of sap occurs even if root system is absent.
• Some tall plants have zero root pressure (Gymnosperms).
• Root pressure is absent in actively transpiring plants.
• Xylem sap shows negative hydrostatic pressure as it is under tension in normal condition.

4. Capillarity theory (Physical force theory) By Bohem :

• Physical forces and dead cells (xylem with lignified wall) are responsible for translocation.
• Water is raised to certain level due to capillarity.
• Capillarity is due to surface tension, cohesive and adhesive forces of water.
• Water conducting elements have lignified walls and are with lumen (xylem vessels and tracheids)
• Combined cohesive forces of water and adhesive forces of water with xylem wall form continuous water column.
• Owing to capillarity, water is conducted upwards against gravity.

Objection to capillarity theory :

• Continuous capillary tube is essential but tracheids have thickened, tapering closed end walls.
• Lower end of capillary tube not in direct contact with soil water.
• Tall trees show wide lumen in xylem vessels. Narrower the capillary tube, higher level of water column is raised.

5. Cohesion – Tension theory (Transpiration pull theory) By Dixon and Joly :

• Widely accepted theory of ascent of sap.
• Based on cohesion and adhesion with transpiration pull developed.
• Strong force of attraction of water molecules : Cohesive force
• Strong force of attraction of water molecules and lignified walls of xylem : Adhesive force
• Water loss is in the form of water vapour, mainly through stomata is transpiration.
• Owing to combined action of cohesive and adhesive forces, a continuous water column is maintained through xylem.
• Transpiration pull developed due to water loss in leaf vessels is transmitted downwards towards root.
• Water lost from stomata causes increased D.RD. of mesophyll cells which in turn takes water from xylem of leaf.
• A gradient of suction pressure or D.ED. is set in, due to transpiration, which causes tension or pull. Owing to this, water column is pulled upwards through xylem.
• It is passive pull of water against gravity which results in ascent of sap.

Objections to transpiration pull theory :

• Formation of gas bubbles due to temperature fluctuations may not keep water column continuous.
• Vessels as tabular structure are much evolved and efficient in conduction but this theory assumes trachieds are more efficient.
• If transpiration is checked due to some artificial means like application of Vaseline, then also ascent of sap occurs, (clogging of stomata due to application of Vaseline)
• Ascent of sap occurs in plants which are deciduous, (leaf fall)

Transport of mineral ions-

• Minerals are elements which play an important role in vital processes in metabolism. Thus they are essential elements for plants.
• Elements required in large amount, Macro elements : e.g. N, P C, H, O, etc.
• Elements are required in small amount, Micro elements : e.g. B, Cu, Mn, Co, etc.
• Soil is a chief source of minerals and they are absorbed in dissolved (ionic) form through root system.
• Minerals are absorbed by plants from their surrounding environment (atmosphere – C, H, O) and soil (inorganic materials).
• Absorption of minerals is independent of that of water.
• Minerals are transported with ascent of sap. Hence root is source and they get lodged at the required organ.
• Unloading of the transported material is by diffusion from veins and cells uptake them.
• Minerals can be remobilized inside plant body from older leaves to young leaves, e.g. R S, N, K, etc. But those parts of structural framework are not disturbed, e.g. Ca.
• Nitrogen in inorganic ion form and amino acids, amides in organic form are transported through xylem.
• Some exchange of material takes place between xylem and phloem.

Transport of food-

• Food is synthesised in chloroplast containing cells.
• Part of plant where food is synthesised is source (leaf) and where it is utilized is sink e.g. root.
• Translocation of food occurs from source to sink through phloem. The movement or transport of food from one part to other part is called translocation of food.
• Sieve tubes (phloem) and vessels (xylem) are ideal for vertical or longitudinal transport. Sieve tubes for downward transport.
• The lateral or horizontal translocation occurs through medullary rays (parenchyma) from phloem to pith or cortex.
• Food is translocated in soluble form sucrose along concentration gradient set from sink.
• Vertical translocation – (longitudinal transport)
  From leaves i.e. source to sink (root) in downward direction or growing point (stem) and seed germination, corm, bulbil germination in upward manner.
• Lateral translocation – occurs in root and stem.
  • Radial translocation from phloem to pith.
  • Tangential translocation from phloem to cortex.

• Phloem transport is bidirectional. Phloem sap has sucrose, and water with other sugar, amino acids and hormones.
• Mechanism of sugar transport through phloem – Mass Flow hypothesis or Munch’s Pressure flow theory is – most widely accepted concept.
• Other theories are diffusion, activated diffusion, electro osmosis, protoplasmic streaming.
• Ernst Munch theory : Glucose synthesised in photosynthesis which increases osmotic concentration of photosynthetic cell → Endo osmosis → water absorbed from adjacent cells and xylem → Turgidity of cell →Increased turgor pressure → sugar from photosynthetic cell forced into sieve tube → This is vein loading.
• Root cell (sink) → utilization of sugar → polymerisation of sugar to starch → osmotic concentration lowered. Exosmosis → hence water lost to adjacent cells → decrease in turgidity → Turgor pressure lowered → Turgor pressure gradient is set → Translocation of food passively along concentration gradient → This is vein unloading.
• Sugar is used at the sink or stored and excess water transported to xylem.

Objections of theory –

• Bidirectional flow is not explained.
• Pressure flow is a physical process.

Transpiration-

• From the constant absorption of water 5% is utilized and 95% surplus water is lost through aerial parts in the form of mainly water vapour.
• Guttation : Loss of water in liquid form (1%), occurs from water stomata or hydathode.
• Transpiration : Water lost in the form of water vapour mainly foliar transpiration.
• Types of Transpiration
  

Structure of stomatal apparatus-

• Stomatal apparatus has guard cells, stoma and accessory cells.
  
• The elliptical pores (opening – stoma) are bounded by two guard cells, either kidney shaped or dumbbell shaped cells.
• Guard cells are modified epidermal cells, nucleated cells with uneven thick wall – Inner wall thick and inelastic, outer wall is thin and elastic, with chloroplasts.
• Accessory cells/Subsidiary cells –
  Specialized epidermal cells that surround guard cells. They are reservoir of K⁺ ions.
• Opening and closing of stomata Is controlled by turgidity of guard cells.
• During daytime → Thrgld guard cells due to endoosmosls → ExertIon of T.P on outer thin wall → elastic wall stretch out → Thick walls pulled apart → stoma opens.
• During night-time → flaccid guard cells due to exosmosis → outer elastic wall relaxes → Inner thick walls pushed → stoma closes.
• Diurnal changes In osmotic potential are responsible for flaccidity and turgidity of guard cells.
• As per starch-sugar hypothesis → DurIng day time starch gets converted to sugar by enzyme phosphorylase → Increase osmotic potential → entry of water
  Reverse reaction during night → stoma close

As per proton pump theory — Transport of H⁺ and K⁺ ions

• During daytime – starch converted to malic acid → dissociation into malate and protons (H⁺) → H⁺ in subsidiary cells → K⁺ ions from subsidiary cells to guard cells → open stomata Potassium malate → Increase osmotic potential → endoosmosis (turgidity)
• At night → uptake of K⁺ and Cl^– ions is checked by abscissic acid – change In permeability, osmotic potential → Hypotonic guard cells → exosmosis → flaccid → stoma close

Advantages of Transpiration:

• Removal of excess water
• Helps In absorption of water
• Cooling effect
• Helps in gaseous exchange
• Maintains turgor of cells
• Ascent of sap

Disadvantage – Excessive transpiration causes wilting injury and that may lead to death of plant.

Transpiration : A necessary evil – (By Curtis)

• During daytime stomata remain open thus help in gaseous exchange – for respiration and photosynthesis
• Productivity is adversely affected if stomata remain closed
• When stomata are open transpiration cannot be avoided.

Know the scientists :
Scientists — Their theories/discoveries

1. B.S. Meyer – Coined the term Diffusion Pressure Deficit D.RD.
2. Atkins and – Osmotic absorption Pristley theory
3. Kramer and – Non-Osmotic absorption Thimann theory
4. J. Pristley – Root pressure theory
5. Bohem – Capillarity theory
6. Dixon and Joly – Cohesion Tension theory
7. Munch – Pressure flow theory
8. Steward – Starch-sugar interconversion theory
9. Levitt – Proton transport theory
10. Curtis – Transpiration as ‘a necessary evil’
11. S. Hales – Term root pressure

By going through these Maharashtra State Board 12th Science Chemistry Notes Chapter 14 Biomolecules students can recall all the concepts quickly.

Maharashtra State Board 12th Chemistry Notes Chapter 14 Biomolecules

Biomolecules: Biomolecules are lifeless molecules that combine in a specific manner to produce life or control biological reactions. Examples: They are carbohydrates, lipids, proteins, nucleic acids. They play
an important role in the functions of organisms.

Carbohydrates: Carbohydrates are optically active polyhydroxy aldehydes or ketones or compounds that can be hydrolyzed to polyhydroxy aldehydes or polyhydroxy ketones.

Classification of Carbohydrates:

Preparation of glucose: Glucose is prepared either from cane sugar or from starch.

Reactions:

Glucose can be represented by Fischer projection formulae and cyclic structure by Haworth projection formulae. Fructose is ketohexose and is made by the isomerization of glucose. It is laevorotatory and belongs to the D series. Fructose can be represented by Fischer projection formulae and cyclic structure by Haworth projection formulae. Disaccharides are sucrose, maltose, cellobiose, lactose, etc. Polysaccharides are starch, cellulose, glycogen, etc.

Proteins: Proteins are naturally occurring polymeric nitrogenous organic compounds containing 16% nitrogen and peptide linkages. Proteins are classified into fibrous proteins (keratin, hair, skin, nails) and globular proteins (hemoglobin, thyroglobulin). The structure of a protein can be studied at different levels called primary, secondary, tertiary, and quaternary. Proteins on hydrolysis give a mixture of α-amino acids .
Amino acids are classified into three types-basic, acidic, and neutral amino acids.
Peptide linkage (-CONH) in an amide formed between -COOH and -NH₂ group by elimination of water molecule.

Enzymes: Enzymes are biological catalysts for various chemical reactions in living organisms. Enzymes are required in small quantities. They act as catalysts and reduce the activation energy for a particular reaction. In many industrial processes, specific reactions are carried with the use of enzymes extracted from organisms.

Nucleic acids: Nucleic acids are esters of phosphoric acid with sugar. They control the synthesis of proteins and are also responsible for storing the genetic information of living organisms and passing the information from one generation to another.
Chromosomes contain two types of nucleic acids: Ribonucleic acid RNA and deoxyribonucleic acid DNA Nucleoside: A base-sugar unit
Nucleotide: A base-sugar-phosphoric acid unit. Nucleotides are monophosphates of nucleosides.

By going through these Maharashtra State Board 12th Science Chemistry Notes Chapter 13 Amines students can recall all the concepts quickly.

Maharashtra State Board 12th Chemistry Notes Chapter 13 Amines

Amines are nitrogen-containing organic compounds having basic character.

1. Classification of amines :

2. Methods of preparation and the reactions of primary amines :

3. Electrophilite aromatic substitution :

4. Preparation and reactions of arene Diazoniuni salts :

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 5 Origin and Evolution of Life students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 5 Origin and Evolution of Life

Origin of life (Protobiogenesis)-

1. Attributes of living organisms : Responsiveness, growth, metabolism, energy transformations and reproduction.
2. Various theories and hypotheses to propose origin of life :

Name of the theory	Characteristic point	What does the theory say?
Theory of special creation	Oldest theory. No scientific proof. Only religious beliefs.	All living organisms are created by a supernatural power.
Cosmozoic theory/Theory of Panspermia	NASA has reported fossils of bacteria­like organisms on a piece of Martian rock recovered from Antarctica.	Life descended to the earth from other planets in the form of cosmozoa/panspermia.
Theory of spontaneous generation (Abiogenesis)	Disproved by Louis Pasteur.	Life originated from non-living material
Theory of biogenesis	Explains only the continuity of life.	Living organisms produced from pre-existing living forms, by process called reproduction.

Chemical Evolution of Life (Self-assembly theory of origin of life)-

1. Theory of biochemical origin of life : Life originated on earth by combinations of several chemicals through constant chemical reactions over a long period of time.
Formulated by Haeckel, developed by Alexander I. Oparin (1924) and J. B. S. Haldane (1929).

2. The steps in the process of chemical evolution :

• Origin of Earth and Primitive atmosphere : Big-Bang theory of Georges Lemaitre (1931). Formation of reducing atmosphere.
• Formation of ammonia, water and methane : Formation of CH₄, NH₃, H₂O and H₂S.
• Formation of simple organic molecules : Formation of monosaccharides, amino acids, purines, pyrimidines, fatty acids, glycerol, etc. Formation of water bodies resulting into ‘hot dilute soup’ or ‘primitive broth’.
• Formation of complex organic molecules : Formation of complex organic molecules like polysaccharides, fats, proteins, nucleosides and nucleotides. Protoproteins → proteins.
  Formation of protein molecules : Landmark in the origin of life.
• Formation of Nucleic acids : Formation of Nucleotides→nucleic acids (RNA, DNA) →acquired self-replicating ability→ fundamental property of living form.
• Formation of Protobionts or Procells : First form of life called protobionts was formed from nucleic acids by coacervation.

Protobionts : Prebiotic chemical aggregates having some properties of living system.
Protobionts also called Coacervates (Oparin) and protenoids or microspheres (Sidney Fox)

Coacervates and microspheres were non¬living colloidal aggregations of lipids and proteinoids respectively. They turned into eobionts or protocell.

Showed growth and division and hence considered as first primitive living system.

• Formation of first cell : First cell developed by formation of RNA and DNA system. First cell was anaerobic, heterotrophic and obtained energy by chemoheterotrophic processes.

Stanley L. Miller and Harold C. Urey provided the first experimental evidence for Oparin’s chemical evolution theory.

3. RNA World Hypothesis :

• First proposed by Carl Woese, Francis Crick and Leslie Orgel in 1960.
• Sidney Altman and Thomas Cech independently found out that RNA can also act as biocatalyst which is termed as Ribozyme.
• Early life must have been based exclusively on nucleic acids, most probably RNA.

Organic Evolution-

• Evolution (Latin word, e = from; volvere = to roll) : The act of unrolling or unfolding of nature.
• Organic evolution : Slow, gradual, continuous and irreversible changes through which the present-day complex forms of the life developed (or evolved) from their simple pre¬existing forms.
• Charles Darwin’s definition of evolution :
  ‘Descent with modification’.
• Lamarck’s theory (Theory of origin of acquired characters/inheritance of acquired characters and use and disuse of organs) : The traits are acquired due to internal force, changes in environment, new needs and the use and disuse of organs. This gives rise to new species after several generations. Lamarckism was disproved by August Weismann.
• Weismann’s theory of Germplasm : Variations produced in somatic cells (somatoplasm) are not inherited while variations produced in germ cells (germplasm) are inherited to next generation.

Darwinism-

1. Darwinism or theory of origin of species by Natural Selection.
2. Darwin’s book : ‘The origin of species by Natural Selection’, wrote in 1859 after observations of variations between the tortoises and finches on Galapagos islands.
3. C. Lyell’s viewpoint on which Darwin’s theory was based : The natural forces that existed in the past are same as those existing at present.
4. Wallace also made similar observations.
5. R. Malthus provided the idea that increase in human population leads to competition and struggle for existence of human species.
6. Five main postulates of Darwinism :

• Overproduction (Prodigality of nature)
• Struggle for existence
• Organic variations
• Natural selection (H. Spencer termed natural selection as ‘survival of fittest’)
• Origin of new species

7. Evidences Darwinism include :

• Evolution of long-necked Giraffe came to existence.
• Black colour peppered moths evolved gradually as new species.
• DDT resistance

8. Drawbacks and Objections to Darwnism :

• Darwin wrongly considered minute non- heritable fluctuating variation as principal factors. They do not form part of evolution.
• He did not distinguish somatic and germinal variation and considered all variations are heritable.
• He did not explain the ‘arrival of the fittest’. He did not explain the cause, origin and inheritance of variations and of vestigial organs.
• He could not explain the extinction of species.
• Intermediate form during evolution were not recognised.
• He could not explain existence of neutral flowers and the sterility of hybrids.

Mutation Theory-

1. Hugo de Vries proposed mutation theory based on his observations on Oenothera lamarckiana.
2. Though offspring resemble their parents in many characters, some sudden and spontaneous variations are seen in them, which is said to be mutations or discontinuous variations.
3. Main features of mutation theory :

• Large, sudden and discontinuous variations, inheritable changes in a population which provide the raw material for organic evolution.
• Mutation may be useful or harmful. Useful mutations are selected by nature.
• Accumulation of useful mutations over a period of time leads to the origin and establishment of new species, while harmful mutations are eliminated by nature or can remain in population.

4. Objections to Mutation Theory :

• The large and discontinuous variations were chromosomal aberrations which bring about minor changes.
• Rate of mutation is very slow.
• Chromosomal aberrations are unstable and hence not important in evolution.

5. Speciation (Formation of new species) :

• Small Darwinian variations are directional. Variations due to mutations are large, sudden, random.
• Darwin’s opinion : Gradual, inheritable variations over a long period of time, lead to speciation.
• De Vries’s opinion : Mutations cause speciation.
• Saltation : A single step large mutation.

Modern Synthetic Theory of Evolution-

1.  R. Fischer, J. B. S. Haldane, T. Dobzhansky, J. Huxley, E. Mayr, Simpson, Stebbins, Fisher, Sewall Wright, Medel, T. H. Morgan, etc. together have synthesised the modern theory of evolution.
2. Stebbins suggested five key factors for evolution : Gene mutations, chromosomal mutations, genetic recombinations, natural selection and reproductive isolation → together bring about evolution of new species.
3. Population : All individuals of the same species form population.
4. ‘Mendelian population’ : Small groups of interbreeding populations.
5. Gene pool : Gene pool is the total genetic information or sum total of genes of all individuals in a Mendelian population.
6. Factors affecting gene pool : Migration, replacement of one generation by another in the Mendelian population.
7. Gene frequency : The proportion of an allele in the gene pool, to the total number of alleles at a given locus.
8. Factors of Modern synthesis theory:

• Gene Mutation : Sudden permanent heritable change in the genetic material is called mutation. Single gene mutations are called point mutations. Chromosomal aberrations and ploidy too cause mutations. All mutations lead to variations.
• Genetic recombination : Crossing over in sexually reproducing organisms cause variations , during gamete formation. Crossing over also create recombination.
  Crossing over : Exchange of genetic material occurs between non-sister chromatids of homologous chromosomes.
• Gene flow : Movement of genes into or out of a population. Migration of organism, or gametes (dispersal of pollens) or segments of DNA (transformation).
• Genetic drift : Any random fluctuation (alteration) in allele frequency, occurring in the natural population by pure chance. Smaller populations may show genetic drift.
• Chromosomal aberrations : The structural, morphological change in chromosome due to rearrangement cause chromosomal aberrations.

Types of aberrations :

• Deletion : Loss of genes from chromosome.
• Duplication : Repetitions of genes or doubling of chromosome number.
• Inversion : Sequence of the genes get inverted due to 180° twist.
• Translocation : Transfer (transposition) of a part of chromosome or a set of genes to a non-homologous chromosome.

Natural selection : Main driving force behind the evolution. It brings about evolutionary changes by favouring differential reproduction of genes that bring about changes in gene frequency from one generation to next generation. The ‘fittest’ (well adapted) survives and leaves more progeny. E.g. Industrial melanism in peppered moth (Biston betularia) is example of natural selection in action.

Isolation : The separation of the population of a particular species into smaller units which prevents interbreeding between them is isolation.

Isolating mechanisms : Barrier which prevents gene flow or exchange of genes between isolated populations.

Type of isolating mechanisms :

Mechanism of organic evolution-

1. During evolution population evolves and not the individual.
2. Basic processes which bring about evolution : Mutations, gene recombination, gene flow (migration),
genetic drift, natural selection, isolation and speciation.

Hardy-Weinberg’s principle-

Hardy-Weinberg’s equilibrium/principle/law states that ‘at equilibrium point both the gene (allele) frequency and genotypic frequency remain constant from generation to generation’, only in diploid, sexually reproducing, large, free interbreeding population if mating is random and in absence of selection and other evolutionary forces.
Hardy-Weinberg equilibrium equation : p² + 2pq + q² = 1

Adaptive Radiation-

Adaptive radiation is the process of evolution which results in transformation of original species to many different varieties. E.g. (1) Darwin’s Finches on Galapagos islands. (2) Australian Marsupials.

Evidences of organic evolution-

Evolutionary evidences are based on following types of disciplines : Palaeontology, comparative anatomy, embryology and molecular biology

Speciation-

• Speciation : The process of formation of a new species from the pre-existing species.
• Species : A group of similar organisms that can interbreed and produce a fertile offspring in nature.
• Types of speciation:

Geological time scale –

Human Evolution-

1. Major changes in evolutionary development of man :

• Increase in size and complexity of brain and enhanced intelligence with increased cranial capacity.
• Bipedal locomotion, erect posture.
• Opposable thumb.
• Shortening of forelimbs and lengthening of hind limbs.
• Development of chin. Orthognathous face.
• Broadening of pelvic girdle, development of lumbar curvature.
• Articulated speech, art, development of tools, social and cultural development.

2. Classification of mammals:

3. Origin and evolution of human being :

(1) Order Primates is divided into two suborders – Prosimii (including lemurs, lorises : and tarsiers) and Anthropoidea (including : New world monkeys – Ceboidea, Old world monkeys-Cercopithecoidea, Apes and :
Man – Hominoidea).
(2) Hominoidea evolved in Miocene in three • separate lines are shown as under :

• Hyalobatidae – Gibbons
• Pongidae – Gorilla, Chimpanzee and Orangutan
• Hominidae – Primates with human characteristics.

4. Palaeontological evidences of human • evolution : The available fossils are skulls, • mandibles, teeth, bones like humerus, femur and stone implements.
5. Important stages in the origin of man :

• Ape like stage : Dryopithecus
• Men-like stage : Ramapithecus
• Connecting link between ape and man : Australopithecus.
• Handy man : Homo habilis
• Ape man : Homo erectus
• Advanced prehistoric man : Homo : neanderthalensis (Neanderthal man)
• Modern man : Homo sapiens

By going through these Maharashtra State Board 12th Science Biology Notes Chapter 10 Human Health and Diseases students can recall all the concepts quickly.

Maharashtra State Board 12th Biology Notes Chapter 10 Human Health and Diseases

Introduction-

1. Health : World Health Organization (WHO) define health as ‘the state of complete physical, mental and social well-being and not merely the absence of disease or infirmity’.
2. Health is metabolic and functional efficiency of living organisms.
3. Hygiene : Science of rules of health.
4. Important factors to achieve good health : Hygienic balanced diet, clean drinking water, personal and community hygiene, regular physical exercise, knowledge about diseases and their effect on body, proper disposal of wastes and control of vectors.
5. Immune system : The ability to resist almost all types of these foreign bodies is possible due
   to immune system. It protects human beings from various pathogens or infectious agents.
6. Resistance : The ability to prevent the damage or disease, through our defence mechanism.

Immunity-

1. Immunity: Immunity is the resistance exhibited by the host towards infections caused by pathogens and their products.
2. Immunology: Study of immune system, immune responses to foreign substances and their role in resisting infection by pathogens.
3. Edward Jenner : Started the concept of immunity. Cowpox vaccine was developed by him.
4. Antigen : Any foreign substance invading body and capable of stimulating an immune response.
5. Antibody : The protective chemicals produced by immune cells in response to antigens are called antibodies.

6. Types of immunity-

7. Innate immunity :

• Inborn immunity which is non-specific and not affected by immunization.
• The barriers of innate imunity are as follows:
  

8. Acquired immunity :

(1) Specific or adaptive immunity acquired during lifetime due to infections.
(2) It involves formation of antibodies from the destruction of foreign antigens.
(3) Unique features of acquired immunity are specificity, diversity, discrimination between self and non-
self and memory.
(4) Types of acquired immunity :

9. Cells of immune system :

10. Mechanism of action of B-lymphocytes to antigens :

B-lymphocytes → sensitized directly by antigens and helper T-cells.
Activated B-lymphocyte → multiplies rapidly → Clone of plasma cells and memory B-cells produced → Plasma cells produce → Glycoproteins, called antibodies → Antibodies circulated through humor/ body fluids like blood and lymph → The antibody → bind to a cell membrane or they remain free.

11. Three main functions of free antibodies :

Agglutination	Opsonisation	Neutralization
Immobilization of foreign particles in mass and then engulfing them by phagocytes.	Coating the bacteria to facilitate the phagocytosis by macrophages.	Neutralizing toxins released by bacteria.

12. Vaccination :

• Vaccination : Administration of inactivated pathogen or antigenic protection of particular pathogen for protecting against a particular pathogen, is called vaccination.
• Vaccine : Inactivated pathogen or antigens of a specific disease.
• Vaccination is a primary prevention as it helps the body to recognize and eliminate pathogenic organism.
• Disease control on mass scale is done through vaccination. E.g. Measles, polio, tetanus and whooping cough, tuberculosis, etc. are prevented through vaccination.

Structure of antibody-

1. Antibodies are highly specific glycoproteins which can neutralize specific antigens.
2. Chemically they are Immunoglobulins (Igs), produced after antigenic stimulation.
3. Production in plasma cells which are formed by B-lymphocytes.
4. Rate of production of antibodies is very rapid, i.e. about 2000 molecules/second.
5. Structure of antibody :

• ‘Y’-shaped molecule. Having four polypeptide chains : Two heavy or H-chains and two light or L-chains.
• Y-structure formed from four polypeplidc chains are held together by disulfide bonds (-s-s-).
• Hinge : This is region holding together arms and stem of antibody.
• Two distinct regions : Variable region and the constant region.
• Paratope : This is antigen binding site present in variable region.
• Epitope : Antigen has antigenic determinant site, called epitope.
• Bivalent antibodies : Antibodies having two antigen binding sites.
• Serology: Study of antigen-antibody interactions.
• FormatIon of antigen-antibody complex: Epitopes (On antigens) and paratopes (on antibody) react with each other. Each antibody Is specific for specific antigen due to variable regions having small variations. Specific antibody binds to specific antigen forming an antigen-antibody complex.
• Antigen on Blood Cells: Antigens (A, B, D) on the surface of human red blood cells : responsible for different blood groups.
•  Blood group systems : ABO, Rh. Duffy, Kidd. Lewis, R MNS, Bombay blood group. etc.

(12) ABO Blood Groups:

(13) Rh factor :

• Landsteiner and Wiener (1940) discovered Rh factor or D antigen on the surface of RBCs of Rhesus monkey. Hence called Rh factor.
• Rh positive (Rh+ve) person has D antigen. Rh negative person lacks it.
• Rh (D) antigen induces a strong immunogenic response when introduced into Rh-ve individuals.
• Haemolytic diseases of the newborn (HDN), or erythroblastosis foetalis occurs when an Rh —ve mother conceives Rh + ve foetus.

Common Human Diseases-

10. Cancer : Cancer is caused due to abnormal, uncontrolled and purposeless division of cells which may form tumour.

(1) Neoplasm : Masses of tissue which form lumps due to uncontrolled cell division.
(2) Oncologists : Oncologists are the physicians and researchers who specialize in the study, diagnosis, treatment and prevention of cancer.
(3) Tumour is mass of undifferentiated cells.

(4) Two types of tumours :

Benign / Non-malignant Tumour:

• Slow growth and Larger size
• Does not spread to other body parts.
• Usually harmless.
• But may sometimes become malignant.
  e.g. Adenoma and Fibroid.
• Brain tumour can be fatal, though it is benign.

Malignant tumour or cancer”

• Rapid growth and not much bIgger.
• Spreads to other body parts. via blood or lymph. (The process of metastasis)
• Usually harmful.
• Overcrowding and disruption of normal cells.

(5) Types of Cancer : Five main types according to tissue on which they thrive.

(6) Causes of Cancer : Also called carcinogenic factors.

(7) Treatment of Cancer :

• Chemotherapy
• Radiotherapy
• Surgery
• Immunotherapy
• Supportive therapy

11. AIDS :

(1) AIDS : Acquired immuno deficiency syndrome, fatal and incurable illness caused by a retrovirus (ss RNA) called HIV (Human immunodeficiency virus).
Body’s immune system is weakened increasing vulnerability causing many life-threatening opportunistic infections, neurological disorders and malignancies.

(2) Structure of HIV :

• Spherical, 100 to 140 nm in diameter, with centrally located two ss RNA molecules and reverse transcriptase enzymes.
• Covering of two layers of proteins.
• The outer layer is of matrix protein (pi7) with additional layer of lipid.
• Impregnated with glycoprotein GP120 and GP 41.
• Inner layer is capsid protein (p24)
• Replication of HIV in dividing T₄ lymphocytes. They remain in latent state in lymphoid cells.

(3) Blood, semen and cerebrospinal fluid (CSF) show maximum concentration of HIV in infected person. Lesser extent seen in tears, milk, urine, saliva, cervical and vaginal secretions.

(4) Transmission of virus :

• Unsafe sexual contact : Oral, vaginal and anal sex.
• Blood : Blood transfusions or sharing syringes, needles, etc.
• Transplacental (From mother to child during pregnancy via placenta) and by nursing mother through breast milk.
• Accidental needle injury, artificial insemination with infected semen and transplantation with infected organs.
• Through urine, tears, saliva, breast milk and vaginal secretions if these secretions enter passes in the body through injury.

(5) Clinical manifestations : Four broad categories.

(6) Preventive measures :

• Prevention is the only measure as there is no cure for AIDS.
• Education of highrisk group, about HIV transmission.
• Disposable needles and syringes.
• Sexual habits to be modified.
• No sharing of toothbrushes, razors, etc.
• Blood to be screened before receiving.

Routine screening must for –

• Blood donors.
• Organ donors (kidney, liver, lung, cornea).
• Donors of semen and growth hormone.
• Patients undergoing haemodialysis.
• Pregnant females in highrisk group.

(7) Laboratory diagnosis :

• ELISA (Enzyme-Linked Immunosorbent Assay) : This test is for detection of AIDS.
• Western Blot : Second and confirmatory test which detects specific antibody to viral core protein and envelope glycoprotein.

(8) Treatment of AIDS : Antiretroviral therapy (ART) : Antiretroviral drugs for reducing viral load and prolong the life of HIV patient. E.g. TDF (tenofovir), EFV (Efavirenz), Lamivudine (3TC), etc.

Adolescence-

1. Adolescence Is transitional stage of physical and mental development during puberty and the legal adulthood. National youth policy defines phase of adolescence during 13—19 years. This period Is marked with sexual and reproductive maturity mental development, adalt Identity and transition from socioeconomic and emotional dependency to relative independence.

2. Stages of Adolescence :

3. Physical changes of adolescence:

• Growth spurt.
• Sexual development
• Emotional and social changes

4. Mental Health and Adolescence:

• Confusion, irritation. moodiness, frustration, nausea, less concentration, hyper activities, anger. effects on lifestyles like obesity, addictions, accidents, leading to ill health. etc. are common problems in adolescent age.
• Psychoses or neuroses may appear.
• Psychoses include delusions, hallucinations. disturbance In the thinking process, etc.
• AmnesIa (loss of memory). Bullirnia (extreme over indulgence in food), Anxiety (fear or apprehension), Anorexia nervosa (emotional aversion to food) depression (sadness, inactivity reduced to enjoy life, etc.), illusions, hallucination, etc.
• Characterized by number of cognitive, emotional, behavioural, physical and attitudinal changes.
• Parental communication and other conditions mould the adult personality.
• Improper peer pressure may result into addictions, like smoking, taking drugs, etc.

5. Treatment: Treatment of such disorders should be done only through counselling and not medicines with due respect to rights of children. Mental health Gap Action Programme (mhGAP) gives the guidelines as per WHO for treating such cases. Parental relations are most important in any treatment.

Addiction –

1. Addiction : Compulsive use of substance despite its harmful consequences is addiction. Addiction cause the impairment of physical, physiological and psychological functions of the body.
2. Addictive substances : Alcohol, opioids, cocaine, nicotine and some behaviours such as gambling.
3. All addictive behaviours share key neurobiological features, involving brain pathways of reward and reinforcement.
4. Neurotransmitter dopamine released during motivation.
5. Neurological changes are reversible after the substance abuse or behaviour is discontinued.
6. Causes of substances abuse during adolescence :

• Parental neglect and insufficient parental supervision and monitoring.
• No communication between child and parents.
• Absence of poorly defined rules.
• Family conflicts.
• Favourable parental attitudes towards alcohol and drug uses.
• Risk taking behaviour.

7. Measures to control drug abuse :

• Always remember ‘Prevention is better than cure’.
• Children should not be pressurized. Over expectations from them should be avoided.
• Suitable education and counselling whenever required.
• Sublimation and channelization of the energy of child in sports, studies and other constructive activities.

Drugs Abuse-

1. Drugs and alcohol use in youth leads to many harmful effects. Improper lifestyle with dangerous behaviour pattern should not be accepted as it is hazardous for all.
2. The drugs of abuse are opioids, cannabinoids and alkaloids of coca and hallucinogens.

3. Addiction and Dependence :

• Inherent addictive nature of alcohol and drugs result into psychological attachment to certain effects-such as euphoria and a temporary feeling of well-being.
• Repeated use of drugs increases the tolerance level of the receptors present in our body.
• Person getting addicted, starts self-destructive behaviour.
• Withdrawal symptoms : If regular addictive substance is discontinued, it results in withdrawal symptoms. All the symptoms seen in such person is called withdrawal syndrome, which is characterized by anxiety, trembling, nausea and sweating.

4. Effects of Drug/Alcohol Abuse :

• Reckless behaviour, vandalism and violence.
• Excessive doses of drugs can cause coma and death due to respiratory failure, heart failure or cerebral haemorrhage.
• Overdose and even deaths occur if there is weird combination of drugs and alcohol.

5. Warning signs of drug and alcohol abuse among youth :

• Drop in academic performance.
• Unexplained absence from school/college.
• Lack of interest in personal hygiene, withdrawal, isolation, depression, fatigue, aggressive and rebellious behaviour, deteriorating relationships with family / friends.
• Loss of interest in hobbies.
• Change in sleeping and eating habits.
• Fluctuations in weight, appetite, etc.
• May turn to crime for money.

6. Other hazards : Intravenous injections of drugs can cause serious infections like HIV and hepatitis B.

7. Long-term effects : Loss of equilibrium, liver cirrhosis, pancreatitis. Damage to nervous system and liver (cirrhosis). Use of drugs and alcohol during pregnancy adversely affects the foetus.

8. Performance enhancers :

• Sportspersons use drugs to enhance performance.
• Narcotic analgesics, anabolic steroids, diuretics and certain hormones to increase muscle strength and bulk and to promote aggressiveness and overall improvement in their performance.
• Anabolic steroids have side effects :

(a) Effects in females : Masculinization in females, increased aggressiveness, mood swings, depression, abnormal menstrual
cycles, excessive hair growth on the face and body, enlargement of clitoris, deepening of voice.

(b) Effects in males : Acne, increased aggressiveness, mood swings, depression and reduction of size of the testicles, decreased sperm production, kidney and liver dysfunction, breast enlargement, premature baldness, enlargement of the prostate gland.

9. Prevention and Control : Habits such as smoking, taking drug or alcohol should be avoided right from young age. Identify the situations which can form addictions and take remedial measures. Help from parents and teachers should be sought.