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Life Processes | : Nutrition, , Quick Revision, , The process wherein an organism uses food and, obtains energy from it in order to carry out its, functioning is called nutrition., , Nutrients are the substances required for proper, growth and maintenance of a living body., , There are two modes of nutrition:, , 1. Autotrophic Mode of Nutrition, ¢ Autotrophic nutrition is performed by the, autotrophs that synthesise organic food, in the form of carbohydrates from carbon, dioxide and water in the presence of sunlight, and chlorophyll to convert them into stored, forms of energy., , , , This process of food synthesis is known as, photosynthesis., Examples of autotrophs are green plants, (producers) and some bacteria., , e General reaction involved in the process of, photosynthesis is, , 6CO,+ 12H,O C,H,0,, Carbon Water Chlorophyll’ Carbohydrate, , dioxide, + 60, +6H,O, Oxygen Water, ¢ Major events occurring in photosynthesis are, (i) Absorption of light energy by chlorophyll., (i) Conversion of light energy into chemical, energy., (iii) Splitting of water molecules into hydrogen, and oxygen., , (iv) Reduction of carbon dioxide to carbohydrates,, , Sunlight, , Leaves in green plants have some structures, known as chloroplasts (containing, chlorophyll) which are main site for the, process of photosynthesis to occur:, , ¢ In leaf, some other structures are ‘also present, such as stomata (tiny pores present on the, surface of the leaf) that participate in gaseous, exchange during photosynthesis, but it is also, responsible for large amount of water loss., These pores close when there is no need of, carbon dioxide for photosynthesis. Guard., cells are the bean-shaped cells that frame the, stomatal openings., , , , Stomatal pore (a) Open, (b) Closed, , °, , Each pair of guard cells is meant to control the, opening of the stomata and hence control the, rate of diffusion of gases and water vapour into, and out of the leaf., , Plants require some raw materials other than, water like nitrogen, phosphorus, iron and, magnesium that are taken up from the soil., , ¢ Nitrogen is an essential component for the, synthesis of proteins and other compounds. It, is mainly taken up in the form of inorganic, nitrates or nitriles or in organic form (prepared, from N,)., , e

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Life Processes, , , , 2. Heterotrophic Mode of Nutrition, ¢ Heterotrophic nutrition is performed by an, , organism that cannot make its own food and, obtains it from other organisms. Thus,, heterotrophs obtain carbon and energy from, organic molecules already produced by the, autotrophs., e.g. Herbivores, carnivores, omnivores,, saprotrophs and parasites., , °, , Heterotrophic mode of nutrition can be of, following three types, , (i) Holozoic nutrition is the mode of, nutrition in which herbivores (plant-eaters),, carnivores (meat-eaters) and omnivores, (both plant and meat-eaters) take complex, molecules which are then broken down, into simpler and soluble molecules,, , e.g. Amoeba, cow, goat, dog, cat, human, being, etc., , Saprotrophic nutrition is the mode of, nutrition in which saprotrophs (organisms, that have saprotrophic nutrition) feed on, dead organic matter by breaking down, complex materials outside the body and, then absorb it, e.g. yeast and bacteria., , , , , , Parasitic nutrition is the mode of nutrition, in which parasites (an organism that live, either on or into the body of another, organism) obtain their nutrition without, killing them. e.g. Plasmodium, ticks, lice,, leech, tapeworm, flatworm, Cuscuta, (Amarbel), etc., , 3. Process of Nutrition in Different Organisms, As the food and the way it is obtained is different for, different types of organisms, so there is different, digestive system in various organisms., , 4, Nutrition in Amoeba, , © Amoebais a unicellular organism with holozoic, mode of nutrition. It takes place with the help, of temporary finger-like extensions called, pseudopodia., , ¢ Different stages of nutrition in Amoeba, include ingestion, digestion, absorption and, egestion., , Nucleus, eZ Pseudopodia, , Food particle, | Food vacuole, (b) Digestion oo particle, , |, , , , (a) Ingestion, , , , (c) Absorption, , _ Undigested food, , Ng) Egestion * removed, , Different stages of nutrition inAmoeba, , 5. Nutrition in Human Beings, , Digestion is a catabolic process where complex and, large components of food are broken down into, simpler forms with the help of hydrolytic enzymes, which are absorbed by different parts of the body., The digestive system of humans constitutes a long, tubular alimentary canal and digestive glands., , IL. Alimentary Canal, Itis a long tube where the entire process of digestion, takes place. It is an internal coiled tube, which runs, from anterior mouth to the posterior anus., The complete process of ingestion, digestion,, absorption, assimilation and egestion of food, material is carried out within the alimentary canal, itself. The major portions of alimentary canal are, discussed below, (i) Mouth It acts as the first part of the digestive, system from where the food enters into the, alimentary canal. Mouth mainly comprised of, two major parts, ¢ Tongue It is a highly muscular sensory, organ present at floor of buccal cavity., It bears several taste buds for basic taste such, as sweet, bitter, salty, sour., Tongue also helps in mixing food with saliva., ¢ Teeth These are hard structures present on, the bones of both lower and upper jaw.

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Humans have 20 milk teeth and 32 permanent, teeth. Four different types of teeth, are incisors, (for cutting the food), canines (for tearing of, food), premolars and molars (for crushing,, chewing and grinding of food)., , (ii) Pharynx is small and funnel-shaped. It is, located behind the oral cavity.It communicates, with both oesophagus and trachea., , (iii) Oesophagus It is a thin, long muscular tube, that leads into stomach. Its opening is covered, by leaf-like cartilaginous structure called, epiglottis., , (iv) Stomach It is the most dilated J-shaped part of, the alimentary canal. This serves as a storehouse, of food where partial digestion takes place, through the secretion of gastric glands., , (v) Small Intestine It is the longest part of, alimentary canal which is the site of complete, digestion of food into different components., , ¢ Secretions from liver and pancreas enter the, intestine to help in the digestion process., , ¢ Small finger-like projections called villi are, present and help in nutrient absorption., , ¢ Herbivores have longer small intestine as, plants have cellulose that takes time to digest., , (vi) Large Intestine Although shorter, but is, called large intestine because it is wider in, diameter than small intestine., , (vii) Rectum It is the last and broad chamber, , like structure to store faecal matter temporarily., , (viii) Anus It helps in exit of waste material., , , , , Mouth/Buccal cavity. esophagus (food pipe), , Salivary glands 3, , Small intestine, Human digestive system, , IL. Digestive Glands, Various digestive glands are tabulated below., , Digestive, , Glands and Secretion Enzyme Digested, their Position, Salivary gland Saliva Salivary Starch, (Oral cavity) amylase (converts starch, into maltose), Gastric glands Gastric Pepsin, Protein, milk, (Stomach) juice rennin and and lipids, lipase, Liver (above _ Bile None Emulsify large, stomach) fat droplets, Pancreas Pancreatic Amylase, Carbohydrate,, (behind juice lipase, fat, protein, stomach) trypsinogen,, chymotrypsin, ogen, Intestinal Intestinal Erepsin, + Breaks down, glands juice mallase; protein into, (Small intestine) lactase, amino acids., SSC TAS, + Breaks, lipase maltose into, , 2 molecules of, glucose., , + Breaks lactose, into glucose, and galactose., , + Breaks, sucrose into, glucose and, fructose., , 6. Mechanism of Digestion of Food, Various steps involved in digestion of these, nutrients are given below, (i) Ingestion It is the process of food intake by, mouth., Food moistened by saliva, before swallowing is, masticated into smaller particles by teeth., , (ii) Digestion Process of breaking down large, organic molecules into smaller ones is called, digestion., , It is done with the help of enzymes., , (iii) Absorption of Food Protein, carbohydrates,, nucleic acids and nucleotides are absorbed by, blood capillaries present in villi, while fats are, absorbed by lymph ducts.

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Life Processes, , , , Digested food is absorbed by small intestine. Peristaltic movements push the undigested, Lipid molecules are mainly absorbed by small food forward from small to large intestine., intestine. (v) Egestion It involves elimination of, , (iv) Assimilation It is the distribution of digested undigested food through anus., food to various cells of the body. The remaining material after reabsorption of, The food absorbed by villi reaches every cell of water and ions is stored in rectum temporarily, the body and is used to build/repair tissues. and is then removed via anus., , Objective Questions, , Multiple Choice Questions (c) They convert carbon dioxide and water, into carbohydrates in the absence of, Oleccecess liberated during photosynthesis sunlight, comes from water. (d) They constitute the first trophic level in, (a) Oxygen (b) Chlorophyll food chains, tel Carbon loxide (dl Glucose 06. Which among the following organisms, 02. Which of the following equations is the shows parasitic nutrition?, correct summary of photosynthesis? (a) Cuscuta (b) Bacteria, (a) 6CO, + 12H,O— C;H,,0, + 60, + 6H,0 (c) Amoeba (d) Goat, (6007104 Sue Cita + 0; + GH0 07. In which of the following groups of, (c) BCO, + TAP, odes + 60, organisms, food material is broken, untight i, ibranii + 6H,0 down outside the body and absorbed?, (d) 6CO, + 12H,2 ———> C.H,,0, + 6CO, (a) Mushroom, green plants, Amoeba, = + 2H,0 (b) Yeast, mushroom, bread mould, . (c) Paramecium, Amoeba, Cuscuta, 03. From which structure, the free oxygen (d) Cuscuta, lice, tapeworm, gas produced during photosynthesis is, released? 08. Select the correct statement., 4 (NCERT Exemplar), (a) Epidermis (b) Stomata ‘ 3, (a) Heterotrophs do not synthesise their own, (c) Cortex (d) Guard cell food, 04. The internal (cellular) energy reserve (b) Heterotrophs utilise solar energy for, in autotrophs is (NCERT Exemplar) photosynthesis, , (c) Heterotrophs synthesise their own food, , one chee (d) Heterotrophs are capable of converting, uh carbon dioxide and water into, 05. Which of the following statements about carbohydrates, ane . . , ;, the autotrophs is enero CERT Eveipnan) 09. The remaining undigested food material, is eliminated via......... in case of Amoeba., (a) They synthesise carbohydrates from carbon dioxide and water in the presence of (a) absorption, sunlight and chlorophyll (b) digestion, (b) They store carbohydrates in the form of (c)egestion, , starch (d)ingestion

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10. In which part of the alimentary canal,, food is finally digested?, (a)Stomach (b) Mouth cavity, (c) Large intestine (d) Small intestine, , 11. Stomach serves as the storehouse of food, , where complete digestion takes place., , (a) True (b) False, (c) Can't say, , 12. Match the Column I with Column II, and select the most appropriate one, from the options given., , Column I Column II, , A. Amoeba 1. Extensive coiling, B. Trypsin 2. Pseudopodia, C. Liver 3. Pancreatic juice, D. Small intestine 4. Bile, Codes, , A B Cc OD, (a)1 2 4 3, (b)2 1 3 4, (c)2 3 ACT, (d)2 3\y0R 4, , 13. An’enzyme ‘X’ that converts starch to, , simple sugars is also the first enzyme to, , mix with food in the digestive tract., , Identify X’., (a) Pepsin (b) Amylase, (c) Lipase (d) None of these, , Assertion-Reasoning MCQs, , Direction (Q.Nos. 14-18) For the following, , question numbers two statements are given,, one labelled as Assertion (A) and the other, , labelled Reason (R). Select the correct answer, , to these questions from the codes (a), (b), (c), and (d) as given below., (a) Both A and R are true and Ris the correct, explanation of A, (b) Both A and Rare true, but Ris not the, correct explanation of A, (c) Ais true, but Ris false, (d)A is false, but Ris true, , (d) Partially True/False, , 14., , 15,, , 16., , 17., , 18., , 19., , Assertion (A) Leaves are the major, photosynthetic organs of a plant., , Reason (R) They contain chloroplasts., Assertion (A) Amoeba follows holozoic, mode of nutrition., , Reason (R) It is unicellular and, omnivore., , Assertion (A) Walls of the intestine has, numerous villi., , Reason (R) These villiincrease the, surface area of digestion., , Assertion'\(A) Herbivores have longer, small intestine., , Reason (R) Digestion of cellulose takes, time., , Assertion (A) Raw materials needed for, photosynthesis are carbon dioxide, water, and minerals., , Reason (R) Nutrients provide energy to, an organism., , Case Based MCOs, , Read the following and answer questions, from (i) to (v)., , Green plants are called autotrophs, since, they can photosynthesise and prepare, their own food. Other organisms which, depend on plants for food are, heterotrophs., , Photosynthesis is the autotrophic mode of, nutrition followed by green plants and, some bacteria. In this process, light, energy is converted into chemical, , energy which is later used to fuel cellular, activities., , The process of photosynthesis takes, place in chloroplasts through, photosynthetic pigments like, chlorophyll-a, chlorophyll-4, carotene, and xanthophyll.