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Practice Questions (Long Answer)

Long Answer Questions 

Question 1. Explain the process of nutrition in Amoeba.

Answer 1. Amoeba takes in food using temporary finger-like extensions of the cell surface which fuse over
the food particle forming a food-vacuole (Fig. 6.5). Inside the foodvacuole, complex substances are broken down into simpler ones which then diffuse into the cytoplasm. The remaining undigested material is moved to the surface of the cell and thrown out.

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Question 2. Describe the alimentary canal of man.

Answer 2. The alimentary canal is basically a long tube extending from the mouth to the anus. In Figure, we can see that the tube has different parts. Various regions are specialised to perform different functions.

Mouth cavity - Naturally the food has to be processed to generate particles which are small and of the same texture. This is achieved by crushing the food with our teeth. A fluid called saliva secreted by the salivary glands wetted the food to make its passage smooth. The saliva also contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give sugar. The food is mixed thoroughly with saliva and moved around the mouth while chewing by the muscular tongue.
Oesophagus - From the mouth, the food is taken to the stomach through the food-pipe or oesophagus.The lining of
oesophagus has muscles that contract rhythmically in order to push the food forward. These peristaltic movements
occur all along the gut.
Stomach - The stomach is a large organ which expands when food enters it. The muscular walls of the stomach help in mixing the food thoroughly with more digestive juices. These digestion functions are taken care of by the gastric glands present in the wall of the stomach. These release hydrochloric acid, a protein digesting enzyme called pepsin, and mucus. The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin. The mucus protects the inner lining of the stomach from the action of the acid under normal conditions. The exit of food from the stomach is regulated by a sphincter muscle which releases it in small amounts into the small intestine.
Intestine - From the stomach, the food now enters the small intestine. This is the longest part of the alimentary canal which is fitted into a compact space because of extensive coiling. The small intestine is the site of the complete digestion of
carbohydrates, proteins and fats. It receives the secretions of the liver and pancreas for this purpose. The inner
lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption. The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body.

Question 3. Explain the process of breathing in man.

Answer 3. 

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Question 4. Explain the importance of soil for plant growth.

Answer 4. 

1. Anchoring the plant
2. Source of water and minerals
3. Availability of oxygen for respiration of root cells
4. Symbiotic association with microbes

Question 5. Draw the diagram of alimentary canal of man and label the following parts.
Mouth, Oesophagus, Stomach, Intestine

Answer 5. 

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Question 6. How do carbohydrates, proteins and fats get digested in human beings?

Answer 6. Naturally the food has to be processed to generate particles which are small and of the same texture. This is achieved by crushing the food with our teeth. A fluid called saliva secreted by the salivary glands wetted the food to make its passage smooth. The saliva also contains an enzyme called salivary amylase that breaks down starch which is a complex molecule to give sugar. The food is mixed thoroughly with saliva and moved around the mouth while chewing by the muscular tongue. From the mouth, the food is taken to the stomach through the food-pipe or oesophagus.The lining of
oesophagus has muscles that contract rhythmically in order to push the food forward. These peristaltic movements
occur all along the gut. From the mouth, the food is taken to the stomach through the food-pipe or oesophagus.The stomach is a large organ which expands when food enters it. The muscular walls of the stomach help in mixing the food thoroughly with more digestive juices. These digestion functions are taken care of by the gastric glands present in the wall of the stomach. These release hydrochloric acid, a protein digesting enzyme called pepsin, and mucus. The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin. The mucus protects the inner lining of the stomach from the action of the acid under normal conditions. The exit of food from the stomach is regulated by a sphincter muscle which releases it in small amounts into the small intestine.  From the stomach, the food now enters the small intestine. This is the longest part of the alimentary canal which is fitted into a compact space because of extensive coiling. The small intestine is the site of the complete digestion of carbohydrates, proteins and fats. It receives the secretions of the liver and pancreas for this purpose. The food coming from the stomach is acidic and has to be made alkaline for the pancreatic enzymes to act. Bile juice from the liver accomplishes this in addition to acting on fats. Fats are present in the intestine in the form of large globules which makes it difficult for enzymes to act on them. Bile salts break them down into smaller globules increasing the efficiency of enzyme action. The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats. The walls of the small intestine contain glands which secrete intestinal juice. The enzymes present in it finally convert the proteins to amino acids, complex carbohydrates into glucose and fats into fatty acids and glycerol.

Question 7. Explain the mechanism of photosynthesis.

Answer 7. The following events occur during the process of photosynthesis 

(i) Absorption of light energy by chlorophyll.
(ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
(iii) Reduction of carbon dioxide to carbohydrates.

Question 8. Explain the three pathways of breakdown in living organisms.

Answer 8.

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Question 9. Describe the flow of blood through the heart of human beings.

Answer 9. Double circulation
Blood travels twice through the heart in one complete cycle of the body.

  • Pulmonary Circulation : Blood moves from the heart to the lungs and back to the heart.
  • Systemic Circulation : Blood moves from the heart to rest of the body and back to the heart.

Oxygen-rich blood from the lungs comes to the thin-walled upper chamber of the heart on the left, the left atrium. The left atrium relaxes when it is collecting this blood. It then contracts, while the next chamber, the left ventricle, expands, so that the blood is transferred to it. When the muscular left ventricle contracts in its turn, the blood is pumped out to
the body. De-oxygenated blood comes from the body to the upper chamber on the right, the right atrium, as it expands. As the right atrium contracts, the corresponding lower chamber, the right ventricle, dilates. This transfers blood to the right ventricle, which in turn pumps it to the lungs for oxygenation. Since ventricles have to pump blood into various organs, they have thicker muscular walls than the atria do. Valves ensure that blood does not flow backwards when the atria or ventricles contract.

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Question 10. Describe the process of urine formation in kidneys.

Answer 10. The purpose of making urine is to filter out waste products from the blood.Nitrogenous waste such as urea or uric acid are removed from blood in the kidneys. The basic filtration unit in the kidneys, is a cluster of very thin-walled blood
capillaries. Each capillary cluster in the kidney is associated with the cup-shaped end of a tube that collects the filtered urine. Each kidney has large numbers of these filtration units called nephrons packed close together. Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively re-absorbed as the
urine flows along the tube. The amount of water reabsorbed depends on how much excess water there is in the body, and on how much of dissolved waste there is to be excreted. The urine forming in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder. Urine is stored in the urinary bladder until the pressure of
the expanded bladder leads to the urge to pass it out through the urethra. The bladder is muscular, so it is under nervous control, as we have discussed elsewhere. As a result, we can usually control the urge to urinate.

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