NUTRITION AND RESPIRATION IN ORGANISMS - III : LONG ANSWERS

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1. Define nutrition, mention its types and describe each type with examples.
   
   ANS :
   
   
   
   • NUTRITION : The process of intake of nutrients and their utilisation in every living cell of the body is called nutrition.
     
   • TYPES OF NUTRITION : Based on the mode of obtaining food by the organisms, nutrition is classified into two main types-(i) Autotrophic nutrition (ii) Heterotrophic nutrition.
     
   • AUTOTROPHIC NUTRITION : Green plants and some bacteria prepare their own food from inorganic materials like carbon dioxide, water and minerals using pigment chlorophyll. These are called autotrophic organisms and their mode of nutrition is called autotrophic nutrition.
     
   • HETEROTROPHIC NUTRITION : Heterotrophic organisms are those which cannot synthesize their own food. These organisms obtain their food from plants and other animal sources. This type of nutrition is called heterotrophic nutrition. In this type of nutrition, the organic components of the food are digested into simple forms and then utilised by the organism. All animals, bacteria and examples of heterotrophic organisms.
     
     Heterotrophic nutrition is classified into three types : (i) Saprophytic nutrition (ii) Parasitic nutrition (iii) Holozoic nutrition.
     
   • SAPROPHYTIC NUTRITION : Organisms obtaining nutrients from dead and decaying organic matter are called saprophytes and their mode of nutrition is called saprophytic nutrition. Many species of bacteria and different types of fungi are saprophytes.
     
   • PARASITIC NUTRITION : If an organism depends on another living organism for nutrition, its mode of nutrition is called parasitic nutrition. Such organisms are called parasites and the organism from which they obtain nutrition is called host. The host organism is harmed by the parasite. Parasitic nutrition is observed in some bacteria, fungi, flowering plants like cuscuta and animal like ascaris.
     
   • HOLOZOIC NUTRITION : Holozoic nutrition involves intake of parts of plants or animals or an organism as a whole by the process of ingestion which is then digested and absorbed. Some examples are amoeba, frog, insects, human being, etc.
     
   
   
   
2. Describe Photosynthesis in detail.
   
   ANS : Plants synthesize their own food by the process of photosynthesis. Photosynthesis is the process in which plants synthesize food from carbon dioxide and water with the help of sunlight and chlorophyll.
   
   
   
   Photosynthesis takes place in two phases : (1) Light Phase (2) Biosynthetic Phase.
   
   LIGHT PHASE : This phase is called light phase because the presence of light is necessary for it to occur.
   
   The chlorophyll molecule absorbs light energy in the form of photons, gets excited and emits electrons. These electrons travel through electron transport chain present in the chloroplast. During this ATP is synthesized from ADP and inorganic phosphate by photophosphorylation. This ATP is used as energy source in biosynthetic phase.
   
   During the light phase photolysis of water takes place.
   
   
   
   The H⁺ ions reduce NADP (Nicotinamide Adenine Dinucleotide Phosphate) into NADPH₂.
   
   The oxygen released during photosynthesis comes from water and not from carbon dioxide.
   
   The whole process takes place in the grana of chloroplast.
   
   BIOSYNTHETIC PHASE : In this phase the ATP and NADPH₂ formed during the light phase are used for the synthesis of carbohydrates from carbon dioxide. This process takes place in the stroma of the chloroplast.
   
   Calvin Cycle : It is called Calvin cycle as Calvin and Benson had discovered it.
   
   
   
   In this process, the carbon dioxide reacts with Ribulose biphosphate (RuBP) and enters the biosynthetic phase. In the end of the cycle carbohydrate is synthesised and RuBP is regenerated.
   
   The process of photosynthesis is affected by light, temperature, water and carbon dioxide.
   
   
3. Explain the factors that affect Photosynthesis.
   
   ANS : The factors that affect photosynthesis are : (1) light (2) temperature (3) water (4) carbon dioxide.
   
   LIGHT : Intensity and quality of light affect photosynthesis. Chlorophyll absorbs mostly red and orange regions of visible spectrum. The rate of photosynthesis is more in red and orange light. Rate of photosynthesis increases at low intensity of light and decreases at high intensity.
   
   TEMPERATURE : Photosynthesis takes place in the presence of enzymes. At low temperatures the activity of enzymes is low and the rate of photosynthesis is low. As the temperature increases, the enzymes get activated and the process of photosynthesis accelerates. But at very high temperatures the enzymes become denatured and the rate of photosynthesis decreases.
   
   
   
   WATER : The rate of photosynthesis decreases under water-deficient conditions as the stomata remain closed to reduce transpiration. This stops gaseous exchange and hence the photosynthesis as carbon dioxide is not available.
   
   CARBON DIOXIDE : The rate of photosynthesis increases with the increase in the concentration of carbon dioxide up to a certain level. Beyond that level it may have inhibitory effect on the rate of photosynthesis.
   
   
4. Explain : Nutrition in Amoeba.
   
   ANS : The mode of nutrition in amoeba is holozoic. The process of obtaining food is called phagocytosis. Amoeba feeds on microscopic organisms floating on water. The nutrition involves processes like ingestion, digestion, assimilation and egestion.
   
   Process : Amoeba forms pseudopodia to take food. When the tips of
   
   pseudopodia touch each other, the membrane at that point dissolves and the food is encaptured along with lysosomes into food vacuole. Digestive enzymes present in the lysosome digest the food. The digested food diffuses into the cytoplasm and utilized by the cell. This is called assimilation. The undigested food left in the food vacuole is thrown out of the body. This is called egestion.
   
   
5. Describe Nutrition in grasshopper (locust).
   
   ANS : Grasshopper is a herbivorous insect feeding on leaves of plants. The alimentary canal of the grasshopper is divided into three parts : (1) foregut (2) midgut (3) hindgut.
   
   
   
   Foregut : It starts from mouth and extends up to gizzard. It consists of a short pharynx, narrow oesophagus and crop. The gizzard has a muscular wall and its lumen is lined with cuticle which forms six chitinous teeth. A pair of salivary glands along the crop opens into the cavity of the mouth through ducts.
   
   Midgut : It is the region between gizzard and hindgut. At its anterior end there are fingerlike projections called hepatic caecae which open into the midgut and secrete digestive enzymes.
   
   Hindgut : It is the region between the midgut and anus. It consists of three parts. An anterior ileum, a middle colon and a posterior rectum. The rectum opens outside through the anus. The junction of midgut and hindgut has many yellow threadlike minute tubules called Malphighian tubules which work as excretory organs.
   
   PROCESS OF DIGESTION :Grasshopper holds the food with fore legs and ingests it inside the mouth where the food mixes with saliva. The saliva lubricates and makes the food soft. Its digestive enzyme digests starch. The food then passes to the crop via oesophagus where it is stored temporarily. Then it passes into the gizzard where it is ground by chitinous teeth and then passes into the midgut. Here the food is digested by enzymes secreted by hepatic caecae. The digested food is absorbed and the indigested food passes into the hindgut from where it is egested out through the anus.
   
   
6. Write an explanatory note on Human Digestive System.
   
   ANS : Human digestive system consists of alimentary canal and accessory digestive glands. Alimentary canal consists of mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine, colon, rectum and anus. Accessory digestive glands are salivary glands, liver and pancreas. They secrete digestive juices.
   
   
   
   The alimentary canal begins with mouth which is located at the anterior end between two lips. The mouth opens into the buccal cavity which lies between the upper and lower jaws.
   
   The muscular tongue at the floor of the buccal cavity helps in digestion of food.
   
   The upper and lower jaws have four kinds of teeth. (1) Incisors for cutting (2) Cannines for tearing (3) Premolars and (4) Molars for chewing and grinding.
   
   The posterior region of buccal cavity is called pharynx which opens into the oesophagus. The oesophagus opens into the stomach which is situated on the left side of the abdomen. The inner wall of the stomach secretes gastric juices. The stomach opens into the duodenum through pyloric valve which is guided by sphincter muscle.
   
   The proximal region of small intestine is called duodenum. It is U-shaped and receives the secretion of liver and pancreas through a common bile duct. The middle region of small intestine is called jejunum and the distal region is called ileum.
   
   Ileum is about 7 m long. The inner wall of the small intestine has long fingerlike projections called villi. These increase the surface area for absorption. The small intestine opens into the large intestine. There is a projection called vermiform appendix at the junction of two intestines.
   
   The large intestine opens into the rectum which, in turn, opens out by anus. The anus is guarded by sphincter muscles.
   
   
7. Explain the exchange of gases in plants.
   
   ANS :
   EXCHANGE OF GASES IN ROOT AND STEM :
   
   
   
   
   
   • Oxygen is present between soil particles.
     
   • Roots take up oxygen by the process of diffusion through the root hairs of piliferous layer.
     
   • This oxygen then passes into other root cells.
     
   • Carbon dioxide from the root cells moves out into the soil through the similar route.
     
   • Root hairs are not present in all parts of the root.
     
   • The parts devoid of root hair have a layer of dead cells having tiny openings called lenticels. In woody plants the bark has lenticels.
     
   • Gaseous exchange occurs between the soil and inner living cells through lenticels.
     
   
   EXCHANGE OF GASES IN LEAVES :
   
   
   
   
   
   • There are numerous tiny apertures called stomata on the leaf surface.
     
   • During respiration the atmospheric oxygen diffuses into the stomata and then into the leaf cells.
     
   • Stomata opens and releases carbon dioxide into atmosphere when the concentration of carbon dioxide increases in the cells.
     
   
   
   
8. Write Important Points on Respiration in Animals.
   
   ANS :
   
   
   
   • Different animals have different respiratory organs.
     
   • Amoeba and paramoecium exchange gases through body wall.
     
   • Fish respire through gills.
     
   • Frog, lizard, birds and man have lungs for respiration.
     
   • Frogs respire through skin and lungs.
     
   • Atmospheric oxygen diffuses through their moist skin into the blood capillaries.
     
   • Carbon dioxide from the blood diffuses out into the atmosphere through skin.
     
   • Similar process occurs during the exchange of gases in lungs.
     
   • The exchange process occurs according to the Law of Partial Pressures of gases.
     
   • Insects like locust, housefly, cockroach, etc. possess trachea for respiration.
     
   • The tracheal system reaches every part of the body.
     
   • Air enters the tracheal system through spiracles situated on the lateral sides of the body.
     
   • Oxygen reaches each and every cell through trachea.
     
   • Carbon dioxide released by the cells moves out to the atmosphere through spiracles.
     
   
   [Last 5 points describe respiration in insects.]
   
   
9. Describe Respiration In Human Being.
   
   ANS :
   HUMAN RESPIRATORY SYSTEM :
   
   
   
   • The human respiratory system is well-developed.
     
   • It consists of nostrils, nasal cavity, pharynx, larynx, trachea, bronchi and lungs.
     
   • Nostrils are the opening of nasal cavity.
     
   • The oxygen-rich air enters nasal cavity through the nostrils.
     
   • The deoxygenated air (containing CO₂) is expelled out through nostrils.
     
   • The mucus in nasal cavity keeps it moist so that dust particles and microbes in the air are trapped there and do not enter lungs.
     
   • Nasal cavity also warms and moistens the air.
     
   • Air enters pharynx through nasal cavity and then into trachea (wind pipe) through a slit called glottis.
     
   • Glottis is protected by a cartilaginous flap called epiglottis.
     
   • As glottis is covered by epiglottis during the swallowing of food, the food does not enter the wind pipe.
     
   • Trachea is a wide tubular structure supported by C-shaped cartilaginous rigs.
     
   • Trachea divides into two bronchi which lead into the lungs.
     
   • There is a pair of lungs situated in thoracic cavity.
     
   • The lungs are covered by two membranes called pleura.
     
   • Brochi branch into many bronchioles in the lungs. Each bronchiole terminates in a sac called alveolar sac.
     
   • The walls of the alveoli are thin and covered by blood capillaries.
     
   
   
   MECHANISM OF BREATHING :
   
   
   
   • Intake of air into lungs is called inhalation.
     
   • When the diaphragm and the muscles attached to the ribs contract, the volume in the thoracic cavity increases, the air pressure decreases and the oxygen-rich air from the atmosphere enters the lungs through nostrils.
     
   • Alveolar sacs are filled with oxygen-rich air and exchange of gases occurs.
     
   • When the diaphragm relaxes the volume of the thoracic cavity decreases, the pressure increases and the air containing carbon dioxide is expelled out of lungs through nostrils.
     
   • This is called exhalation.
     
   • The process of inhalation and exhalation is collectively called breathing.
     
   
   
   EXCHANGE OF GASES IN TISSUES :
   
   
   
   • Respiratory gases are exchanged between the blood and the tissues.
     
   • Oxygen is utilised in the tissues and carbon dioxide is released.
     
   • The blood coming from lungs to the tissues has higher concentration of oxygen and lower concentration of carbon dioxide.
     
   • The difference in concentration induces exchange of gases between tissue and blood capillaries.
     
   
   
   The end result of respiration process is that the oxidation of simple food molecules like glucose in mitochondria releases energy which is stored in ATP.
   
   
10. Distinguish between autotrophic nutrition and heterotrophic nutrition.
    
    ANS :
    
    
    
11. Distinguish between photosynthesis and respiration.
    
    ANS:
    
    

NUTRITION AND RESPIRATION IN ORGANISMS - II : BRIEF ANSWERS

ANSWER IN BRIEF

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1. Describe Aerobic respiration.
   
   ANS: The respiration that takes place in the presence of oxygen is called aerobic respiration. Majority of the organisms show aerobic respiration.
   
   During aerobic respiration glucose is completely broken down into carbon dioxide and water and the energy that is released is stored in ATP.
   
   Since the process takes place in the cell it is called Cellular respiration or Internal respiration.
   
   
   
2. Describe Anaerobic respiration.
   
   ANS: Anaerobic respiration takes place in the absence of oxygen. It is seen in micro-organisms like bacteria, yeast, fungi, endoparasites and in muscle cells.
   
   In plants, carbon dioxide and ethanol are formed as end products.
   
   
   
   Lactic acid is formed as end product in muscle cells.
   
3. How does the respiration in plants differ from that in animals ?
   
   ANS: The respiration in plants differs from that in animals in the following ways :
   
   
   
   • All parts of a plant like root, stem and leaf perform respiration individually.
     
   • There is little transport of gases from one part of plant to another.
     
   • The rate of respiration in plants is much slower than that in animals.
     
   
   
4. Distinguish between aerobic and anaerobic respiration.
   
   ANS:
   
   
5. What is photolysis? Give reaction.
   
   ANS:Photolysis is the process of breaking a molecule with the help of light. For example, photolysis of water during light phase of photosynthesis:
   
   H₂O ---> 2H⁺ + 1/2 O₂ + 2e^-
   
   
6. Distinguish between breathing and (cellular) respiration.
   
   ANS:
   
   

NUTRITION AND RESPIRATION IN ORGANISMS - I : MCQs & SHORT ANSWERS

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MULTIPLE-CHOICE QUESTIONS

SELECT THE CORRECT ALTERNATIVE:

1. The autotrophic organisms contain ______ pigment.
   
   
   
   1. methylene blue
   2. chlorophyll
   3. phenolphthalin
   4. carbon black
      
   
   
2. Oxygen released during photosynthesis comes from ______.
   
   
   
   1. water
   2. carbon dioxide
   3. chloroplast
   4. sunlight
      
   
   
3. Rate of photosynthesis is more in ______ and ______ light.
   
   
   
   1. red, green
   2. red, orange
   3. yellow, orange
   4. green, orange
      
   
   
4. The process of obtaining food in amoeba is called ______.
   
   
   
   1. pyrolysis
   2. phosphorylation
   3. phagocytosis
   4. phenocytosis
      
   
   
5. The cavity between the upper and the lower jaws is called ______ cavity.
   
   
   
   1. thoracic
   2. nasal
   3. hepatic
   4. buccal
      
   
   
6. The length of ileum is about ______ m.
   
   
   
   1. 5
   2. 6
   3. 7
   4. 8
      
   
   
7. The energy released during cellular respiration is stored in ______.
   
   
   
   1. ATP
   2. glucose
   3. lungs
   4. ileum
      
   
   
8. The layer of dead cells having tiny openings on the roots is called ______.
   
   
   
   1. root nodule
   2. stomata
   3. chlorenchyma
   4. lenticels
      
   
   
9. Fish respire through ______.
   
   
   
   1. Gills
   2. spiracles
   3. lungs
   4. skin
      
   
   
10. In insects the air enters the tracheal system through openings called ______.
    
    
    
    1. spiracles
    2. nostrils
    3. lungs
    4. bronchi
       
    
    
11. Lungs are situated in ______.
    
    
    
    1. buccal cavity
    2. nasal cavity
    3. thoracic cavity
    4. stomach
       
    
    
12. Oxidation of glucose takes place in ______.
    
    
    
    1. lungs
    2. heart
    3. mitochondria
    4. chloroplast
       
    
    
13. The lungs are covered by two membranes called ______.
    
    
    
    1. glottis
    2. pleura
    3. epiglottis
    4. epidermis
       
    
    
14. The process which releases energy from nutrients is called ______.
    
    
    
    1. respiration
    2. photosynthesis
    3. nutrition
    4. absorption
       
    
    
15. Which organism shows parasitic mode of nutrition ?
    
    
    
    1. Cascuta
    2. Plasmodium
    3. ascaris
    4. All three
       
    
    
16. During photosynthesis electrons are released from ______.
    
    
    
    1. Electron Transport System
    2. Chloroplast
    3. Light
    4. All three
       
    
    
17. During which phase of photosynthesis ATP is used as an energy source ?
    
    
    
    1. Light phase
    2. Light synthetic phase
    3. Biosynthetic phase
    4. Grana phase
       
    
    
18. During biosynthetic phase carbon dioxide combines with ______.
    
    
    
    1. RuBP
    2. starch
    3. glucose
    4. PGA
       
    
    
19. Cockroach shows ______ mode of nutrition.
    
    
    
    1. herbivorous
    2. carnivorous
    3. omnivorous
    4. grazing
       
    
    
20. Gizzard is found in the digestive system of ______.
    
    
    
    1. man
    2. amoeba
    3. locust
    4. earthworm
       
    
    
21. The function of incisors is ______.
    
    
    
    1. cutting
    2. tearing
    3. grinding
    4. chewing
       
    
    
22. 
    
    
    
    4. 
       
    
    
23. 
    
    
    
    4. 
       
    
    
24. 
    
    
    
    4. 
       
    
    

SHORT QUESTIONS

ANSWER IN SHORT:

1. Define : Nutrition.
   
        ANS : The process of intake of nutrients and their utilization in every living cell of the body is called nutrition.
   
2. What is the aim of the nutrition ?
   
        ANS : The aim of nutrition is to provide energy to the body and help in biosynthesis of body constituents.
   
3. Mention two main modes of nutrition.
   
        ANS : Autotrophic nutrition and heterotrophic nutrition are two main modes of nutrition.
   
4. From what do autotrophic organisms synthesize glucose and other molecules ?
   
        ANS : Autotrophic organisms synthesize glucose and other molecules from inorganic molecules like carbon dioxide, water and some minerals using solar energy.
   
5. What do we mean by autotrophic organisms ?
   
        ANS : Those organisms which can synthesize their own food by using carbon dioxide, water and solar energy are called autotrophic organisms.
   
6. What do we mean by heterotrophic organisms ?
   
        ANS : Those organisms which cannot prepare their own food and are dependent on other organisms for nutrition are called heterotrophic organisms.
   
7. Mention different types of heterotrophic nutrition.
   
        ANS : The types of heterotrophic nutrition are : saprophytic nutrition, parasitic nutrition and holozoic nutrition.
   
8. How is energy derived during heterotrophic nutrition ?
   
        ANS : Energy is derived from the intake and digestion of organic nutrients obtained from plant and animal origin.
   
9. Define : Saprophytic nutrition.
   
        ANS : The mode of nutrition in which an organism obtains nutrients from dead and decaying organic matter is called saprophytic nutrition.
   
10. Define : Saprophyte
    
         ANS : An organism which obtains nutrition from dead and decaying matter is called a saprophyte.
    
11. Define : Parasitic nutrition.
    
         ANS : [TEXT BOOK DEFINITION] If an organism depends on another living organism for nutrition, then this mode of nutrition is called parasitic nutrition.
    
    [PROPER DEFINITION] If an organism obtains nutrition from other organism and in turn harms the latter, the mode of nutrition is called parasitic nutrition.
    
12. What is the organism providing food to a parasite called ?
    
         ANS : The organism providing food to a parasite is called 'host'.
    
13. Define : Holozoic nutrition.
    
         ANS : The nutrition obtained by the intake of parts of plants or animals or an organism as a whole by the process of ingestion which is then digested and nutrients are absorbed is called holozoic nutrition.
    
14. By which process do green plants synthesize food ?
    
         ANS : Green plants synthesize food by photosynthesis.
    
15. What does photosynthesis mean ?
    
         ANS : Photosynthesis means synthesis of food with the help of light energy.
    
16. Define : Photosynthesis.
    
         ANS : Photosynthesis is a process in which plants (and some micro-organisms) synthesize food from environmental carbon dioxide and water using sunlight and chlorophyll.
    
17. Write the chemical equation for photosynthesis.
    
         ANS :
    
    
    
    
18. Mention the two phases of photosynthesis.
    
         ANS : The two phases of photosynthesis are (i) Light phase (ii) Biosynthetic phase.
    
19. In which form do the chlorophyll molecules absorb light energy ?
    
         ANS : Chlorophyll molecules absorb light energy in the form of photons.
    
20. What is photophosphorylation ?
    
         ANS : The synthesis of ATP from ADP and inorganic phosphate during the light phase of photosynthesis is called photophosphorylation.
    
21. Write the equation for photolysis of water during photosynthesis.
    
         ANS :
    
    
    
    
22. What is the full form of NADP ?
    
         ANS : The full form of NADP is Nicotinamide Adenine Dinucleotide Phosphate.
    
23. Where does the light phase of photosynthesis take place in the chloroplast ?
    
         ANS : The light phase of photosynthesis takes place in the grana of chloroplast.
    
24. What is formed during the light phase of photosynthesis ?
    
         ANS : ATP and NADPH₂ are formed during the light phase of photosynthesis.
    
25. What happens during the biosynthetic phase of photosynthesis ?
    
         ANS : Carbohydrates are formed from carbon dioxide using ATP and NADPH₂ during biosynthetic phase.
    
26. Where does the biosynthetic phase take place ?
    
         ANS : Biosynthetic phase takes place in the stroma of the chloroplast.
    
27. Who discovered the biosynthetic phase of photosynthesis ?
    
         ANS : Calvin and Benson discovered the biosynthetic phase of photosynthesis.
    
28. How does carbon dioxide enter the biosynthetic phase ?
    
         ANS : Carbon dioxide reacts with Ribulose biphosphate (RuBP) and enters the biosynthetic phase.
    
29. Mention the factors affecting photosynthesis.
    
         ANS : The factors affecting photosynthesis are : (i) light (ii) water (iii) temperature (iv) carbon dioxide.
    
30. What part of visible light is mostly absorbed by chlorophyll ?
    
         ANS : Mostly red and orange region of visible light is absorbed by chlorophyll.
    
31. How does the intensity of light affect the rate of photosynthesis ?
    
         ANS : The rate of photosynthesis increases at low intensity and decreases at high intensity.
    
32. Why does the low temperature inhibit photosynthesis ?
    
         ANS : Low temperature inhibits the rate of photosynthesis because at low temperatures the activity of the enzymes is lowered.
    
33. Why does the rate of photosynthesis decrease at very high temperatures ?
    
         ANS : The rate of photosynthesis decreases at very high temperatures because at those temperatures the enzymes are denatured.
    
34. How are animals classified according to their food habit ?
    
         ANS : Animals are classified as herbivores, carnivores and omnivores according to their food habit.
    
35. On what does amoeba feed ?
    
         ANS : Amoeba feeds on microscopic plants and animals floating on water.
    
36. Mention the processes involved in the nutrition in amoeba.
    
         ANS : The processes involved in the nutrition in amoeba are : ingestion, digestion, assimilation and egestion.
    
37. In which parts is the alimentary canal of a grasshopper divided ?
    
         ANS : The alimentary canal of a grasshopper is divided into three parts : (i) foregut (ii) midgut (iii) hindgut.
    
38. What forms the foregut of a grasshopper ?
    
         ANS : The foregut of a grasshopper starts from the mouth, followed by a short pharynx, a short and narrow oesophagus, crop and extends upto gizzard.
    
39. Which parts does the hindgut of a grasshopper consist of ?
    
         ANS : The hindgut of a grasshopper consists of three parts : (i) an anterior ileum (ii) a middle colon (iii) a posterior rectum.
    
40. What are Malphighian tubules ?
    
         ANS : The yellow thread-like minute tubules in the hindgut of a grasshopper are called Malphighian tubules.
    
41. What do hepatic caecae do ?
    
         ANS : Hepatic caecae secrete digestive enzymes.
    
42. What does the alimentary canal in human digestive system consist of ?
    
         ANS : The alimentary canal in human digestive system consists of mouth, buccal cavity, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus.
    
43. Mention the accessory digestive glands of human digestive system.
    
         ANS : Salivary glands, liver and pancreas are the accessory digestive glands of human digestive system.
    
44. Mention the types of teeth.
    
         ANS : The types of teeth are : (i) incisors (ii) canines (iii) premolars (iv) molars.
    
45. What is the posterior region of buccal cavity called ?
    
         ANS : The posterior region of buccal cavity is called pharynx.
    
46. Through which valve does the stomach open into duodenum ?
    
         ANS : The stomach opens into duodenum through pyloric valve.
    
47. What does the small intestine consist of ?
    
         ANS : The small intestine consists of (i) duodenum (ii) jejunum (iii) ileum.
    
48. What is the function of villi in small intestine ?
    
         ANS : The function of villi is to increase the surface area for absorption in small intestine.
    
49. Where is the vermiform appendix located ?
    
         ANS : The vermiform appendix is located at the junction of the small intestine and the large intestine.
    
50. Define : Inspiration.
    
         ANS : The intake of oxygenated air into lungs is called inspiration.
    
51. Define : Expiration.
    
         ANS : The removal of deoxygenated air containing carbon dioxide from the lungs is called expiration.
    
52. Define : Breathing.
    
         ANS : The alternate process of inspiration and expiration together is called breathing.
    
53. Define : Respiration.
    
         ANS : Respiration is the process involving inspiration and expiration during which every cell of the body receives oxygen and utilises it for oxidation of glucose to release energy.
    
54. Define : Aerobic respiration.
    
         ANS : The respiration that takes place in the presence of oxygen is called aerobic respiration.
    
55. Why is aerobic respiration also called cellular (internal) respiration ?
    
         ANS : Aerobic respiration is also called cellular (internal) respiration because it takes place within the cell.
    
56. Write the chemical equation for aerobic respiration.
    
         ANS :
    
    
    
57. Define : Anaerobic respiration.
    
         ANS : Respiration which takes place in the absence of oxygen is called anaerobic respiration.
    
58. Which organisms exhibit anaerobic respiration ?
    
         ANS : Micro-organisms like bacteria, yeast, fungi and endoparasites exhibit anaerobic respiration.
    
59. Mention end products of anaerobic respiration.
    
         ANS : The end products of anaerobic respiration are carbon dioxide and ethanol in plants and lactic acid in the muscles of animals.
    
60. Write the chemical equation for anaerobic respiration in plants.
    
         ANS :
    
    
    
61. Write the chemical equation for anaerobic respiration in muscles.
    
         ANS :[SA-61]
    
62. Through what does the gaseous exchange occur between the soil and the inner living cells of plants ?
    
         ANS : The gaseous exchange occurs between the soil and the inner living cells of plants through lenticels.
    
63. Through what does the gaseous exchange occur in animals like amoeba/paramoecium ?
    
         ANS : The gaseous exchange occurs through body wall in amoeba/paramoecium.
    
64. Gaseous exchange occurs through ______ in earthworm.
    
         ANS : the skin
    
65. Through what does the frog respire ?
    
         ANS : The frog respires through skin and lungs.
    
66. What is the respiratory organ of insects like locust, housefly and cockroach ?
    
         ANS : Trachea is the respiratory organ of insects like locust, housefly and cockroach.
    
67. Through what does the air enter tracheal system in insects ?
    
         ANS : The air enters tracheal system through openings called spiracles in insects.
    
68. What type of respiratory surface should be for rapid and efficient gaseous exchange ?
    
         ANS : The respiratory surface should be thin, moist, richly supplied with blood capillaries and in direct contact with the atmosphere for rapid and efficient gaseous exchange.
    
69. What does the human respiratory system consists of ?
    
         ANS : Human respiratory system consists of nostrils, nasal cavity, pharynx, larynx, trachea, bronchi and lungs.
    
70. What is glottis ?
    
         ANS : Glottis is a slit through which pharynx leads to trachea.
    
71. Why does the food not enter the windpipe ?
    
         ANS : The food (during swallowing) does not enter the windpipe because the glottis is covered by a cartilaginous flap of skin called epiglottis.
    
72. Name the salivary glands of human digestive system.
    
         ANS : (1) Submendibular salivary gland (2) Sublingual salivary gland
    
73. What is the function of canines?
    
         ANS : The function of canines is'tearing' the food particles.
    

ORGANIC COMPOUNDS -III : LONG ANSWERS

GIVE ANSWER IN DETAIL

*INDEX-TOPIC SEARCH

1. Explain : Alcohol group giving common name, IUPAC name and chemical formula of first five compounds.
   

   ANS :
   

   
   
   • The functional group of an alcohol is -OH.
     
   • The general formula of alcohols is C_nH_{2n + 1}OH where C_nH_{2n + 1} is alkyl group (also written as R) and n=1,2,3,...
     
   • The suffix "-ane" of an alkane is replaced by "-anol" to give name to the corresponding alcohol. For example : CH₄ is methane and CH₃OH is methanol.
     
   • The first five alcohol compounds and their formulas are as follows :
     
     
     

   
   



2. Describe preparation of ethyl alcohol.
   

   ANS : Ethyl alcohol can be prepared by two methods.
   

   
   
   1. Fermentation of carbohydrates
      
   2. Hydration of ethene
      

   
   
   FERMENTATION OF CARBOHYDRATES :
   
   Slow breaking down of carbon compounds in presence of enzymes and in absence of oxygen into simpler compounds is called fermentation.
   
   The sugar (carbohydrates) present in sugarcane, juices of fruits, etc. is first broken down to simple sugars like glucose and fructose by enzyme invertase.
   
   
   
   Glucose (and fructose) is converted to ethanol by the enzyme zymase.[Yeast contains both invertase and zymase].
   
   
   
   HYDRATION OF ETHENE : Ethene reacts with water in presence of concentrated sulphuric acid to form ethyl alcohol.
   
   
   



3. Describe chemical properties of ethyl alcohol.
   

   ANS :
   
   
   
   



4. Explain : Aldehyde group giving common name, IUPAC name and chemical formula of first four compounds.
   

   ANS : Aldehydes are compounds with -CHO as their functional group.
   
   The IUPAC name of an aldehyde is given by replacing "-ane" of the parent hydrocarbon to "-anal". Thus methane (CH₄) becomes methanal (HCHO) and ethane (C₂H₆) becomes ethanal (CH₃CHO).
   
   The common name, IUPAC name and chemical formula of first four aldehyde compounds are as follows :
   
   
   



5. 
   Describe preparation, properties and uses of formaldehyde.
   

   ANS :
   
   PREPARATION : Formaldehyde can be prepared by heating methanol to 600 - 700°C in presence of silver oxide as a catalyst. Methanol is oxidised to methanal (formaldehyde).
   
   
   
   PHYSICAL PROPERTIES :
   

   
   
   • Formaldehyde is a colourless gas.
     
   • Its boiling point is 20°C.
     
   • It is miscible with water.
     

   
   
   CHEMICAL PROPERTIES :
   
      Oxidation : Methanal is oxidised to methanoic acid (formic acid) in presence of oxidising agents like Tollen's reagent, Fehling's reagent, potassium permanganate solution or potassium dichromate solution.
   
   
   {Note : Tollen's reagent contains silver ammonium ion [Ag(NH₃)₂]⁺ }
   
      Reduction : In presence of catalyst palladium [Pd], hydrogen reduces methanal to methanol.
   
   
   
      Addition of HCN : Addition of hydrogen cyanide to methanal gives methanal cyanohydrin.
   
   
   
   USES :
   

   
   
   • Formalin (30 - 35 % solution of formaldehyde) is used to preserve biological specimens because it makes proteins insoluble in water.
     
   • For the manufacture of polymers like phenol-formaldehyde.
     

   
   



6. Write an introductory note on carbonyl compounds.
   

   ANS :
   

   
   
   • The functional group >C=O is known as carbonyl group.
     
   • Aldehydes and ketones are carbonyl compounds.
     
   • When carbonyl group is attached to at least one hydrogen [i.e.it is attached to either two hydrogen atoms or one hydrogen atom and one alkyl group], an aldehyde compound is obtained.
     
   • When carbonyl group is attached to two alkyl groups, a ketone is obtained.
     
     
   • 
     
     
   • The name of an aldehyde is given by replacing "-ane" from the parent hydrocarbon by "-anal". Example : methane → methanal.
     
   • The name of a ketone is given by replacing "-ane" from the parent hydrocarbon by "-anone". Example : propane → propanone.
     

   
   



7. Describe preparation, properties and uses of propanone (acetone).
   

   ANS :
   
   PREPARATION : Acetone is prepared by 'Fischer and Tropsch' process. When ethene, obtained from the cracking of petroleum, and water gas are mixed and passed over cobalt oxide catalyst at 180°C and 150 atm pressure, propanone is obtained.
   
   
   
   PHYSICAL PROPERTIES :
   

   
   
   • Acetone is a colourless, volatile liquid.
     
   • It has a pleasant odour.
     
   • It is miscible with water.
     
   • Its boiling point is 56°C.
     

   
   
   CHEMICAL PROPERTIES :
   
      Reduction : Propanone reacts with hydrogen in presence of catalysts like sodium boron hydride (NaBH₄) or lithium aluminium hydride (LiAlH₄) to yield 2-propanol.
   
   
   
      Oxidation : Propanone is oxidised to ethanoic acid by alkaline potassium permanganate.
   
   
   
      Addition Reaction With HCN : Acetone reacts with hydrogen cyanide to give acetone cyanohydrin.
   
   
   
   USES :
   

   
   
   • As a nail-polish remover.
     
   • In making models, air-plane glue, lacquers, paints, etc.
     
   • In leather industry and in artificial fibres.
     
   • As a solvent in laboratory.
     

   
   



8. What are organic acids ? Explain giving example.
   

   ANS :
   

   
   
   • Organic compounds having -COOH (carboxylic acid) as funcional group are called organic (carboxylic) acids.
     
   • Their general formula is C_nH_{2n + 1}COOH where n = 0, 1, 2, 3,...
     
   • The suffix "-ane" of parent alkane is replaced by "-anoic" to give the name to an organic acid.
     
   • Following table gives common name, chemical name and formula of some organic acids. [Table : 12.4 to be posted- LA-15].
     

   
   



9. Describe preparation, properties and uses of acetic acid (ethanoic acid).
   

   ANS :
   
   PREPARATION :
   
      Fermentation : Acetic acid is manufactured by the fermentation of ethyl alcohol with the help of bacteria (acetobacter). Acetic acid obtained by this process is very less and is called 'Vinegar'.
   
   
   
      Chemical Synthesis : The reaction of methanol with carbon monoxide in the presence of catalyst iodine-rhodium (I₂-Rh) gives acetic acid.
   
   
   
   PHYSICAL PROPERTIES :
   

   
   
   • Acetic acid is a colourless liquid.
     
   • It has pungent smell.
     
   • It is miscible with water.
     
   • Its boiling point is 118°C.
     

   
   
   CHEMICAL PROPERTIES :
   
      Reaction With Metals : Acetic acid reacts with metals such as sodium(Na), potassium(K) or magnesium(Mg) and liberates hydrogen.
   
   
   
      Neutralisation : Acetic acid reacts with an alkali (NaOH or KOH) to form respective salt of acetic acid and water.
   
   
   
      Esterification : Acetic acid reacts with alcohols in presence of concentrated sulphuric acid to form ester.
   
   
   
      Decarboxylation : When acetic acid is heated with soda lime (CaO + NaOH) it loses (-COO) part forming methane.
   
   
   
   USES :
   

   
   
   • As vinegar, acetic acid is used as a preservative and taste-enhancer in food (like pickle).
     
   • As a laboratory reagent.
     
   • As a solvent.
     
   • For the preparation of white lead and lead acetate.
     

   
   



10. Write a note on 'rubber'.
    

    ANS :
    

    
    
    • Rubber is an addition polymer.
      
    • Natural rubber is obtained from the latex of rubber trees.
      
    • Natural rubber consists of a long chain of isoprene (monomer) units.
      
      
      
      
    • Elasticity of natural rubber is low and is less strong.
      
    • Synthetic rubber (neoprene) is obtained by addition polymerization of chloroprene (monomer).
      
    • Vulcanisation of Rubber :
      
      
      
      • Natural rubber becomes brittle below 10°C and melts above 60°C.
        
      • Thus, natural rubber is less elastic and less strong.
        
      • To make natural rubber more elastic and tough, it is mixed with sulphur powder and heated to 100 to 140°C.
        
      • This forms strong links of sulphur between isoprene units.
        
      • This process is called vulcanisation of rubber.
        
      • Vulcanised rubber is used for making rubber bends, tubes and tyres of vehicles.
        
      
      

    
    



11. Describe preparation of polyester and mention its uses.
    

    ANS : Polyester is prepared by reacting two compounds, one having two carboxylic groups and the other having two hydroxyl groups. This forms a long chain of esters called polyester.
    
    
    
       Uses : Polyester fibres are used in textiles industry along with cotton fibres.
    



12. Describe preparation of polyamides (nylon) and mention its uses.
    

    ANS : Polyamides are prepared by reacting two compounds, one having two carboxylic groups and the other having two amide groups. This forms a long chain of amides called polyamides.
    
    
    
       Uses :
    

    
    
    1. As these fibres are strong and waterproof, they are used in making clothes and raincoats.
       
    2. In making fishing nets and in tyres.
       

    
    



13. Describe the cleansing action of soaps and detergents.
    

    ANS :
    

    
    
    • The cleansing actions of soap and detergent are similar.
      
    • Both the soap and detergent have two parts in their molecular structure.
      
    • The hydrocarbon chain forms nonpolar tail which has no attraction for water but is attracted towards dirt or stains.
      
    • The head (negative part) consists of -COONa or SO₃Na group which is polar as it has attraction towards water molecules.
      
    • When soap (detergent) solution is applied on the surface having dirt or stain, its nonpolar part is attracted by nonpolar dirt or stain. the polar part remains in water. This type of arrangement around dirt particles is called 'micelle'.
      
    • As hydrocarbon part remains attached to dirt or stain and the polar part remains in water, dirt is removed from the surface making it clean and water becomes dirty.
      

    
    



14. Distinguish between natural rubber and vulcanised rubber.
    
    ANS :
    
    


15. Write a note on fermentation.
    
    ANS :
    Fermentation :Fermentation is a slow process of breaking down of carbon compounds in the presence of enzymes and in the absence of oxygen.
    Fermentation is used in the manufacture of ethyl alcohol(ethanol) from sugar(carbohydrates). The sugar present in sugarcane, fruit-juices, etc., is first broken down to simple sugars like glucose and fructose by enzyme invertase.
    

    invertase
    C₁₂H₂₂O₁₁ + H₂O → C₆H₁₂O₆ + C₆H₁₂O₆
    Sugar or molasses           glucose       fructose
    

    
    Simple sugars (glucose and fructose) are converted to ethanol by the enzyme zymase.
    

    zymase
    C₆H₁₂O₆          → 2C₂H₅OH + 2CO₂
    glucose             ethanol
    

    
    Yeast is used in this process because it contains both enzymes invertase and zymase.
    
    [NOTE : The text book defines fermentation as a process taking place in absence of oxygen. While describing the preparation of acetic acid from ethanol, it has been mentioned that Vinegar (ethanoic acid) is formed by oxidation of ethanol in air by acetobactor enzyme through fermentation process. This is an example of one of several controversial issues found in the text book.]
    

ORGANIC COMPOUNDS -II : BRIEF ANSWERS

ANSWER IN BRIEF

*INDEX-TOPIC SEARCH

1. Explain : Functional group.
   

   ANS:
   

   
   
   • An atom or a group of atoms responsible for the chemical reactions of an organic compound is known as 'Functional Group'.
     
   • Functional groups are responsible for the properties of an organic compound.
     
   • Functional group is a characteristic of an organic compound.
     
   • Examples :
     
     
     
     1. Alcohol (-OH)
        
     2. Aldehyde (-CHO)
        
     3. Ketone (>C=O)
        
     4. Organic acid (-COOH)
        
     5. Ester (-COOR, R is alkyl part)
        
     6. -X (halogen, X stands for any of Cl, Br, I, F).
        
     
     
   • Thus, CH₃CH₂OH (ethanol) is an alcohol and -OH group decides its properties.
     
   • All compounds having similar functional group have similar properties.
     

   
   



2. Write physical properties of ethyl alcohol.
   

   ANS:
   

   
   
   • Pure ethanol is colourless.
     
   • Its boiling point is 78°C.
     
   • It is miscible with water.
     
   • It is neutral.
     

   
   



3. Mention uses of ethyl alcohol.
   

   ANS:
   

   
   
   • As an antiseptic to clean wounds.
     
   • To sterilise syringes, gauze, etc.
     
   • In alcoholic drinks.
     
   • In preparation of rectified spirit (alcohol containing 5% water).
     
   • As an industrial solvent.
     
   • In preparation of lacquers, varnish and perfumes.
     

   
   



4. Write about the harmful effects of ethyl alcohol.
   

   ANS:
   

   
   
   • Person consuming alcohol becomes addict to it.
     
   • Eyesight weakens and the person may lose eyesight in the long run.
     
   • Ethyl alcohol damages liver and may cause death of the person.
     
   • To restrict consumption of ethyl alcohol, some poisonous substance like methanol or CuSO₄ is added to ethanol. This is called 'Denatured Ethyl Alcohol'.
     

   
   



5. Show that the H atom in the -COOH group has acidic nature.
   

   ANS:The H atom in the -COOH group has acidic nature. The following two reactions are the proof of this.
   
   When acetic acid reacts with a metal like sodium or potassium, hydrogen gas is evolved.
   
   
   
   Acetic acid reacts with an alkali to form the respective salt of acetic acid and water.
   
   
   



6. What is an enzyme ? Write three reactions involving different enzymes.
   

   ANS: An enzyme is a biochemical catalyst which breaks down complex organic molecules into simpler ones. Some reactions involving enzymes are :
   
   
   
   
   



7. Mention the difference between 'Denatured Alcohol' and 'Rectified Spirit'.
   

   ANS:
   

   
   
   • Ethyl alcohol containing 5% water is called 'rectified spirit'.
     
   • Ethyl alcohol containing some poisonous substance like methanol or copper sulphate in small amount is called 'denatured alcohol'.
     
   • The purpose of adding poisonous substance is to prevent people from consuming alcohol as its addiction is harmful in the long run.
     

   
   



8. Explain : Tollen's test.
   

   ANS:
   [NOTE : Though this question appears in the list of questions given at the end of the chapter in the text book (GSEB), the description regarding it is given under the title 'ONLY FOR INFORMATION'. Refer to 'Activity 4' in the text book.]
   

   
   
   • Add sufficient NaOH to a solution of silver nitrate to obtain permanent precipitates.
     
   • Dissolve the precipitates in NH₄OH to prepare Tollen's reagent.
     
   • Add some aldehyde in the test tube containing Tollen's reagent and place it in a beaker containing water.
     
   • Heat the water in the beaker.
     
   • The aldehyde will be oxidised and silver (Ag) metal will be liberated. This silver will appear as a mirror on the inner wall of the test tube.
     

   
   



9. Write addition reactions of formaldehyde and propanone.
   

   ANS: Formaldehyde and propanone show following addition reactions with HCN forming corresponding cyanohydrins.
   
   
   
   
   



10. What is a polymer ? Give its classification.
    

    ANS: A polymer is a long-chain compound with many smaller units called monomers.
    
    Based on their reactions, polymers are classified into (i) Addition polymer and (ii) Condensation polymer.
    



11. What are addition polymers ? Give examples.
    

    ANS: Addition polymers are formed by addition of one or more than one (same or different) unsaturated monomer having double or triple bond.
    
    Polythene, PVC, TEFLON, polypropene, natural rubber, polubutadiene and neoprene are addition polymers.
    



12. What are condensation polymers ? Give examples.
    

    ANS: A polymer formed by the condensation of two or more than two monomers with the elimination of a simple molecule like water or ammonia is called a condensation polymer.
    
    Polyester, polyamides and phenol-formaldehyde are condensation polymers.
    



13. Write a brief note on soap.
    

    ANS: Soaps are sodium or potassium salts of higher fatty acids like stearic or palmitic acid, etc. Soap is in the form of acid, its glycol and ester compounds. The ester compounds are glycerides present in animal fat or vegetable oils. In soaps, -COONa is the functional group attached to the hydrocarbon part.
    
    PREPARATION : On heating vegetable oil or animal fat (esters of higher fatty acids) with sodium hydroxide, sodium salt of fatty acid (soap) and glycerol are formed.
    
    
    
    This process is known as Saponification.
    



14. Write a note on (Synthetic) Detergents.
    

    ANS:
    

    
    
    • (Synthetic) Detergents are sodium salts of long-chain sulphonates.
      
    • In detergents, -SO₃Na is the functional group attached to hydrocarbon part.
      
    • Detergents are superior to soaps as soaps cannot be used with hard water. Soaps form insoluble salts of calcium and magnesium in hard water and cleansing becomes difficult because of Ca⁺² and Mg⁺² ions present in hard water.
      
    • Detergents do not form precipitates with these ions. Due to this detergent is used in lesser quantity and its cleansing effect is retained.
      

    
    



15. Distinguish between soap and detergent.
    
    ANS:
    
    
    


16. 
    

    ANS: