Chapter 12 : NUTRITION AND RESPIRATION

1. Answer the following questions in short.
   1. Which inorganic substances are used as food by autotrophic organisms?
   2. What is the mode of nutrition in fungi?
   3. Name one organism each having saprophytic, parasitic and holozoic mode of nutrition.
   4. Name the process by which plants prepare food.
   5. In addition to carbon dioxide and water, state two other conditions necessary for the process of photosynthesis.
   6. Name the pigment which can absorb solar energy.
   7. Where is chlorophyll mainly present in a plant?
   8. Which structure of food vacuole in amoeba breaks down the food?
   9. From which part of the body is undigested food egested in amoeba?
   10. Name one organism which can live without oxygen.
   11. In which type of respiration is more energy released?
   12. Which part of the root is involved in the exchange of respiratory gases?
   13. Name the respiratory organ of fish.
   14. What are various type of heterotrophic nutrition?
   15. What is the role of hydrochloric acid in our stomach?
   16. Mention the function of enzymes in human digestive system.
   17. Mention the type of respiration taking place in (i) yeast (ii) humans.
   
   ANS
   1. Carbon dioxide and water.
   2. Saprophytic and parasitic.
   3. • Saprophytic : Mushroom (fungi)
      • Parasitic : Tapeworm, ascaris
      • Holozoic : Amoeba, human being
   4. Photosynthesis
   5. Chlorophyll and presence of sunlight.
   6. Chlorophyll
   7. In chloroplast present on leaves of green plants.
   8. Lysosome
   9. Cell membrane
   10. Yeast
   11. Aerobic respiration
   12. Root hair
   13. Gills
   14. Parasitic nutrition, saprophytic nutrition and holozoic nutrition.
   15. Hydrochloric acid makes the food in stomach acidic so that the enzyme pepsin can digest proteins present in food into simpler molecules. It also kills harmful bacteria present in food.
   16. Enzymes break down complex organic molecules present in food into simpler molecules which can be absorbed by the cells of the body easily.
   17. (i)In yeast : anaerobic respiration (ii) In humans : aerobic respiration
   
   
2. Define Nutrition. Name four important nutrients present in food.
   ANS
   • Nutrition is the process of intake of food (nutrients) from which the organism can derive energy.
   • Important nutrients present in food are : carbohydrates, proteins, fats (lipids), vitamins and minerals.
   
   
3. What is autotrophic nutrition? Give one example of autotroph. What are necessary conditions for autotrophic nutrition?
   ANS
   • Autotrophic nutrition is the mode of nutrition by which an organism synthesizes its own food from water and carbon dioxide by the process of photosynthesis.
   • Green plants, Euglena, volvox are examples of autotrophs.
   • Availability of natural inorganic substances like carbon dioxide and water and presence of sunlight and chlorophyll are the necessary conditions for autotrophic nutrition.
   
   
4. What is heterotrophic nutrition? Give one example of heterotroph.
   ANS
   • Heterotrophic nutrition is the mode of nutrition in which an organism cannot synthesize food on its own using carbon dioxide and water but derives energy by digesting organic substances obtained from other organisms (plants and animals).
   • Human being is an example of heterotroph.
   
   
5. Define : (i)Saprophytic nutrition (ii) Parasitic nutrition (iii)Holozoic nutrition. Give one example of each type.
   ANS
   • SAPROPHYTIC NUTRITION: The process of obtaining nutrition from the dead and decaying organic matter is called saprophytic nutrition. Example: nutrition in some bacteria and fungi (mushroom).
   • PARASITIC NUTRITION: The process of obtaining nutrition from the body of other organisms called 'host' in which the host is not benefitted but harmed is known as parasitic nutrition. Example : tapeworm, ascaris, cuscuta.
   • HOLOZOIC NUTRITION: The process of obtaining nutrition by consuming plants or animals in part or whole, digesting them into simpler molecules and then absorbing the nutrients into body cells is called holozoic nutrition. Example : Amoeba, human being.
   
   
6. Describe exchange of gases in leaves of a plant (i) during daytime (ii) at night.
   ANS
   • Exchange of gases in leaves of a plant occurs through tiny pores called stomata present on the surface of the leaves.
   • During daytime photosynthesis occurs in leaves. Therefore, oxygen diffuses out and carbon dioxide diffuses in.
   • At night, in absence of photosynthesis, oxygen diffuses in and carbon dioxide diffuses out.
   
   
7. Describe the process of nutrition in amoeba with labelled diagram of various steps involved.
   ANS
   
   • The mode of nutrition in unicellular amoeba is holozoic and the process is called phagocytosis.
   • INGESTION: Amoeba captures food particles by forming temporary finger-like projections called pseudopodia around food particle. Food along with lysosome enters food vacuole.
   • DIGESTION: Food is digested by digestive enzymes within food vacuole.
   • ABSORPTION: The digested food is absorbed directly into cytoplasm from food vacuole by diffusion.
   • ASSIMILATION: The food absorbed in cell is used to obtain energy and for growth.
   • EGESTION: The undigested food is thrown out of the body by rupturing the cell membrane.
   
   
   
   
   
   
   
8. Draw a labelled diagram of human digestive system and describe the process of digestion.
   ANS
   
   • The human digestive system consists of the alimentary canal and associated glands.
   • The digestive organs are mouth, oesophagus (food pipe), stomach, small intestine and large intestine.
   • The associated glands are salivary glands, liver and pancreas.
   • The food is put in mouth with the help of hands (ingestion).
   • The mouth cavity has teeth, tongue and salivary glands.
   • Teeth are used to cut, chew and grind food particles. Salivary glands secrete saliva which wets the food and tongue mixes the foods with saliva.
   • Enzyme amylase secreted by salivary glands digests starch into maltose.
   • Partially digested food enters stomach through oesophagus.
   • Stomach is located on the left side of abdomen.
   • Food remains in stomach for about three hours.
   • The wall of stomach has three tubular glands which secrete gastric juice which contains dilute hydrochloric acid, enzyme pepsinogen and mucus.
   • Mucus protects stomach from its own secretion of hydrochloric acid and pepsin.
   • Hydrochloric acid makes medium in stomach acidic and kills bacteria.
   • Due to acidic medium, enzyme pepsin digests food proteins.
   • The partly digested food enters small intestine from stomach.
   • In an adult human the length of small intestine is about 6.5 m.
   • Complete digestion of carbohydrates, proteins and fats occurs in small intestine.
   • The small intestine receives alkaline bile (greenish yellow liquid) secreted by liver and stored in gall bladder.
   • Bile converts acidic food into alkaline so that pancreatic enzymes can act on it. Bile salts break fat in small globules making digestion easy.
   • Pancreatic juice secreted by pancreas contains enzymes amylase, trypsin and lipase.
   • Amylase digests starch, trypsin digests proteins and lipase digests fats.
   • The glands in the wall of small intestine secrete intestinal juice containing different enzymes which complete digestion of carbohydrates into glucose, proteins into amino acids and fats into fatty acids and glycerol.
   • The inner wall of small intestine possesses millions of small, finger-like projections called villi. Villi increase the surface area for rapid absorption of digested food by blood.
   • Blood carries digested food to all parts of the body where it is assimilated as part of the cells.
   • The assimilated food is used by the body for energy, growth and repairs.
   • The undigested food passes from small intestine to large intestine where most of the water from undigested food is absorbed.
   • The undigested food (now almost solid) is egested out of the body via anus.
   
   
9. Describe respiration occurring in following parts of a plant: (i) Root (ii) Stem (iii) Leaves
   ANS
   • Respiration (Exchange of Gases) in Root
     
     
     • Plant roots possess tiny root hair which are extension of epidermal cells of root.
     • Root hair are in contact with the air present between the soil particles.
     • Oxygen present in this air diffuses into root hair and reaches all the cells of root for respiration.
     • Carbon dioxide produced in the cells during respiration moves out through root hair by diffusion.
   • Respiration in Stem
     • Stems of herbs (soft plants) possess stomata on their surface.
     • Oxygen from air diffuses into stem through stomata and reaches cells of stem for respiration.
     • Carbon dioxide produced during respiration diffuses out through stomata.
     • Big plants have hard and woody stem without stomata.
     • The bark of such plants has tiny pores called lenticels through which gaseous exchange occurs.
   • Respiration in Leaves
     • The leaves of a plant have plenty of tiny pores called stomata.
     • During night time (in absence of photosynthesis) oxygen from air diffuses in through stomata amd carbon dioxide produced during respiration diffuses out.
   
   
10. What is the difference between autotrophic nutrition and heterotrophic nutrition?
    ANS
    • In autotrophic nutrition, the organism prepares its own food from carbon dioxide and water using sunlight in presence of chlorophyll.
    • In heterotrophic nutrition, the organism cannot prepare its own food and depends on other plants and animals for obtaining food from which it can derive energy.
    
    
11. Write in brief about aerobic respiration.
    ANS
    • The respiration which takes place in presence of oxygen is called aerobic respiration.
    • It occurs in cells, so it is also called cellular respiration.
    • Food (glucose) is broken down into carbon dioxide and water.
    • The energy released during the process is stored in ATP.
      
      
    
    
12. Write in brief about anaerobic respiration.
    ANS
    • Anaerobic respiration occurs without oxygen.
    • It occurs in some micro-organisms (bacteria, yeast, fungi), in endoparasites and in muscle cells.
    • In micro-organisms and plants, glucose is broken down and ethanol and carbon dioxide are produced as end products.
    • In muscle cells of animals, lactic acid is produced as end product.
      
      
    
    
13. Describe human respiratory system.
    ANS
    
    
    • Human respiratory system consists of nostrils, nasal passage, pharynx, laropharynx, trachea, bronchi, lungs and diaphragm.
    • Respiratory air enters nasal cavity through nostrils.
    • Nasal cavity is lined with fine hair and mucus in which dust particles and micro-organisms present in air get trapped.
    • Air passes to pharynx which leads to trachea through a slit called glottis.
    • A cartilaginous flap called epiglottis covers glottis so that food cannot enter trachea during swallowing.
    • Trachea is supported by 'C' shaped cartilaginous rings so that it would not collapse when there is no air in it.
    • Trachea has larynx (voice-box) at its upper end.
    • Trachea divides into two bronchi leading to lungs and each bronchus divides into many smaller bronchioles within lungs.
    • The bronchioles terminate into alveoli.
    • The walls of alveoli are thin and covered by blood capillaries.
    • Gaseous exchange takes place in alveoli.
    
    
14. Describe mechanism of breathing.
    ANS
    • Intake of air into lungs is called inspiration.
    • When the diaphragm and the muscles attached to the ribs contract, the volume inside the thoracic cavity increases, the air pressure within lungs decreases and the oxygen-rich air from atmosphere enters lungs through nostrils.
    • Alveoli are filled with oxygen-rich air and exchange of gases occurs.
    • When diaphragm relaxes the volume in the thoracic cavity decreases, the pressure within lungs increases and the air containing carbon dioxide is expelled out of lungs through nostrils.
    • This is called expiration.
    • The process of inspiration and expiration is collectively called breathing.
    
    
15. Distinguish between breathing and respiration.
    ANS
    
    
    
    
16. 
    ANS