Ans. It will affect the breakdown of starch because the saliva contains an enzyme called salivary amylase that breaks down starch.
2. Name the secretion by which the inner lining of the stomach is protected by hydrochloric acid.
Ans. The gastric gland present in the wall of the stomach secrets mucus protects the inner lining of the stomach from the action of the acid under normal conditions.
3. During deficiency of oxygen in tissues of human beings, which acid is converted into lactic acid?
Ans. During deficiency of oxygen in tissues of human beings, pyruvate is converted into lactic acid which is a three-carbon molecule.
4. What is common for Cuscuta, ticks, and leeches?
Ans. All are parasitic plants and these parasitic plants derive nutrition from plants or animals without killing them.
5. What are the functions of gastric glands present in the wall of the stomach?
Ans. The gastric glands present in the wall of the stomach release hydrochloric acid, a protein-digesting enzyme called pepsin and mucus.
6. How can you test that the rice water contains starch?
Ans. If a few drops of iodine were added to the rice water which contains starch, the colour of starch turns into blue-black in colour.
7. What is the function of pancreatic juice?
Ans. The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.
Ans. The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.
8. Where does aerobic respiration occur in a cell?
Ans. Aerobic respiration takes place in the cytoplasm of a cell.
Ans. Aerobic respiration takes place in the cytoplasm of a cell.
9. What will happen if platelets were absent in blood?
Ans. When we are injured and start bleeding platelets help to clot the blood at these points of injury because the loss of blood from the system would lead to a loss of pressure which would reduce the efficiency of the pumping system.
Ans. When we are injured and start bleeding platelets help to clot the blood at these points of injury because the loss of blood from the system would lead to a loss of pressure which would reduce the efficiency of the pumping system.
10. What is the role of acid in our stomach?
Ans. The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin and kills bacteria and harmful organisms that may be present in food.
Ans. The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin and kills bacteria and harmful organisms that may be present in food.
11. Define transpiration.
Ans. The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration.
Ans. The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration.
12. When air is blown from the mouth into a test tube containing lime water, the lime water turns milky. Why?
Ans. The air that is blown from the mouth contains carbon dioxide gas and when carbon dioxide gas reacts with lime water to form insoluble calcium carbonate and limewater turn milky.
Ans. The air that is blown from the mouth contains carbon dioxide gas and when carbon dioxide gas reacts with lime water to form insoluble calcium carbonate and limewater turn milky.
13. State the function of digestive enzymes.
Ans. Digestive enzymes help to break the complex molecules of food particles into simpler molecules and helps in digestion.
Ans. Digestive enzymes help to break the complex molecules of food particles into simpler molecules and helps in digestion.
14. During respiration where does, the exchange of gas takes place?
Ans. In human, the alveoli provide a surface where the exchange of gases can take place and in-plant massive amounts of gaseous exchange take place in the leaves through stomata.
Ans. In human, the alveoli provide a surface where the exchange of gases can take place and in-plant massive amounts of gaseous exchange take place in the leaves through stomata.
15. Write the correct sequence of anaerobic respiration in yeast.
Ans. Break down of glucose ( in the cytoplasm)→ Pyruvate → Breakdown of pyruvate ( in the absence of oxygen) → ethanol + carbon dioxide.
Ans. Break down of glucose ( in the cytoplasm)→ Pyruvate → Breakdown of pyruvate ( in the absence of oxygen) → ethanol + carbon dioxide.
16. Write the correct sequence of aerobic respiration.
Ans. Break down of glucose → Pyruvate → Breakdown of pyruvate ( in the mitochondria and in the presence of oxygen) → Carbon dioxide + water + energy.
Ans. Break down of glucose → Pyruvate → Breakdown of pyruvate ( in the mitochondria and in the presence of oxygen) → Carbon dioxide + water + energy.
17. Write the correct sequence of air passing during inhalation.
Ans. Nostril → Pharynx → Larynx → Trachea → Lungs (Alveoli)
Ans. Nostril → Pharynx → Larynx → Trachea → Lungs (Alveoli)
18. Name the tissues that transport
(i) water and mineral in a plant
(ii) transport soluble product of photosynthesis in plants.
Ans. (i) Xylem transport water and
(ii) phloem transport soluble product of photosynthesis.
(i) water and mineral in a plant
(ii) transport soluble product of photosynthesis in plants.
Ans. (i) Xylem transport water and
(ii) phloem transport soluble product of photosynthesis.
19. Where does the digestion of fat take place in our bodies?
Ans. The digestion of fat takes place in the small intestine in our bodies.
Ans. The digestion of fat takes place in the small intestine in our bodies.
20. What is the role of saliva in the digestion of food?
Ans. Saliva is secreted by the salivary gland and helps in digestion. The saliva contains an enzyme called salivary amylase, during digestion saliva breaks down starch which is a complex molecule to give sugar.
Ans. Saliva is secreted by the salivary gland and helps in digestion. The saliva contains an enzyme called salivary amylase, during digestion saliva breaks down starch which is a complex molecule to give sugar.
21. What are the final products of carbohydrates, protein, and fats after their digestion?
Ans. The final products of carbohydrates, protein, and fats after their digestion are glucose, amino acids, and fatty acids respectively?
Ans. The final products of carbohydrates, protein, and fats after their digestion are glucose, amino acids, and fatty acids respectively?
22. Stomata of desert plants remain closed during the daytime? How do they take up CO2 and perform photosynthesis?
Ans. Desert plants take up carbon dioxide at night and prepare an intermediate which is acted upon by the energy absorbed by the chlorophyll during the day.
Ans. Desert plants take up carbon dioxide at night and prepare an intermediate which is acted upon by the energy absorbed by the chlorophyll during the day.
23. Write two major components of human urine.
Ans. Water and uric acid are the major components of human urine.
Ans. Water and uric acid are the major components of human urine.
24. A major amount of water selectively reabsorbed by the tubular part of the nephron in humans. What are the two factors on which the amount of water reabsorbed depends?
Ans. 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.
Ans. 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.
25. What happens to glucose, amino acids, salt and water that enter the nephron along with filtrate?
Ans. 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.
Ans. 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.
26. Why is diffusion not sufficient to meet the oxygen requirements of all the cells in multicellular organisms?
Ans. In multicellular organisms, the body size of animals is large, the diffusion pressure alone cannot take care of oxygen delivery to all parts of the body.
27. Write the equation of photosynthesis?
Ans. Equation of photosynthesis is :
6CO2 + 6H2O + (Chlorophyll+ Sunlight)→ C6H12O6 + 6O2
Glucose
28. Name the energy currency in the living organism. When and where it is produced?
Ans. The energy currency in the living organism is adenosine triphosphate ATP. It is produced during photosynthesis in plants and is stored in mitochondria in the cell.
29. What is the structural and functional unit of the kidney?
Ans. A nephron is the structural and functional unit of the kidney.
30. On which of the opening and closing of the stomatal pore depends?
Ans. The opening and closing of the stomatal pore depend on the guard cells.
II. Short answer type questions:
1. How does the guard cell regulate opening and closing the stomatal pores?
Ans. The opening and closing of the pore is a function of the guard cells. The guard cells swell when water flows into them, causing the stomatal pore to open. Similarly, the pore closes if the guard cells shrink.
Ans. Equation of photosynthesis is :
6CO2 + 6H2O + (Chlorophyll+ Sunlight)→ C6H12O6 + 6O2
Glucose
28. Name the energy currency in the living organism. When and where it is produced?
Ans. The energy currency in the living organism is adenosine triphosphate ATP. It is produced during photosynthesis in plants and is stored in mitochondria in the cell.
29. What is the structural and functional unit of the kidney?
Ans. A nephron is the structural and functional unit of the kidney.
30. On which of the opening and closing of the stomatal pore depends?
Ans. The opening and closing of the stomatal pore depend on the guard cells.
1. How does the guard cell regulate opening and closing the stomatal pores?
Ans. The opening and closing of the pore is a function of the guard cells. The guard cells swell when water flows into them, causing the stomatal pore to open. Similarly, the pore closes if the guard cells shrink.
2. State any two differences between arteries and veins.
Ans. Two differences between arteries and veins are:
i. Arteries carry blood away from the heart to various organs of the body whereas veins collect the blood from different organs and bring it back to the heart.
ii. Since the blood emerges from the heart under high pressure, the arteries have thick, elastic walls. whereas veins have thin walls because the blood is no longer under pressure, instead they have valves that ensure that the blood flows only in one direction.
Ans. Two differences between arteries and veins are:
i. Arteries carry blood away from the heart to various organs of the body whereas veins collect the blood from different organs and bring it back to the heart.
ii. Since the blood emerges from the heart under high pressure, the arteries have thick, elastic walls. whereas veins have thin walls because the blood is no longer under pressure, instead they have valves that ensure that the blood flows only in one direction.
3. What function is served by the following:
(i) gastric sphincter (ii) anal sphincter.
Ans. (i) The exit of food from the stomach is regulated by a sphincter muscle which releases it in small amounts into the small intestine.
(ii) The exit of waste which is unabsorbed food material is regulated by the anal sphincter.
(i) gastric sphincter (ii) anal sphincter.
Ans. (i) The exit of food from the stomach is regulated by a sphincter muscle which releases it in small amounts into the small intestine.
(ii) The exit of waste which is unabsorbed food material is regulated by the anal sphincter.
4. List any four strategies used by plants for excretion.
Ans. (i) They can get rid of excess water by transpiration through stomata.
(ii) Many plant waste products are stored in cellular vacuoles.
(iii) In the plant many of their tissues consist of dead cells and these waste products may be stored in leaves that fall off.
(iv) Other waste products are stored as resins and gums, especially in old xylem.
Ans. (i) They can get rid of excess water by transpiration through stomata.
(ii) Many plant waste products are stored in cellular vacuoles.
(iii) In the plant many of their tissues consist of dead cells and these waste products may be stored in leaves that fall off.
(iv) Other waste products are stored as resins and gums, especially in old xylem.
5. Leaves of a healthy potted plant were coated with Vaseline. Will these plants remain healthy for long? Give reasons for your answer.
Ans. If the leaves of a healthy potted plant were coated with Vaseline then these plants will not remain healthy for a long time and die because the vaseline layer prevents the plant from receiving sunlight, photosynthesis, respiration, and transpiration.
Ans. If the leaves of a healthy potted plant were coated with Vaseline then these plants will not remain healthy for a long time and die because the vaseline layer prevents the plant from receiving sunlight, photosynthesis, respiration, and transpiration.
6. Write three differences between aerobic and anaerobic respiration.
Ans. Three differences between aerobic respiration are :
(i) aerobic respiration takes place in the presence of air (oxygen) and anaerobic respiration takes place in the absence of air.
(ii) The aerobic respiration takes place in the mitochondria and anaerobic respiration takes place in the cytoplasm.
(iii) In aerobic respiration, pyruvate converted into carbon dioxide, water, and energy in form of ATP and in anaerobic respiration pyruvate converted into ethanol and carbon dioxide.
7. What is the internal energy that reserve in plants?
Ans. The carbohydrates which are not used immediately are stored in the form of starch, which serves as the internal energy reserve to be used as and when required by the plant
Ans. The carbohydrates which are not used immediately are stored in the form of starch, which serves as the internal energy reserve to be used as and when required by the plant
8. How do leaves of plants help in excretion?
Ans. Many plant waste products are stored in cellular vacuoles. Waste products may be stored in leaves that fall off.
Ans. Many plant waste products are stored in cellular vacuoles. Waste products may be stored in leaves that fall off.
9. Differentiate between and autotrophs and heterotrophs.
Ans. Autotrophic nutrition involves the intake of simple inorganic materials from the environment and using an external energy source like the Sun to synthesise complex high-energy organic material.
Heterotrophic nutrition involves the intake of complex material prepared by other organisms.
Ans. Autotrophic nutrition involves the intake of simple inorganic materials from the environment and using an external energy source like the Sun to synthesise complex high-energy organic material.
Heterotrophic nutrition involves the intake of complex material prepared by other organisms.
10. How is the process of transpiration useful for plants?
Ans. Transpiration helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves. It also helps in temperature regulation.
Ans. Transpiration helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves. It also helps in temperature regulation.
11. Plants have low energy needs as compared to animals. Explain.
Ans. Plants have low energy needs as compared to animals because plants do not move, and plant bodies have a large proportion of dead cells in many tissues.
Ans. Plants have low energy needs as compared to animals because plants do not move, and plant bodies have a large proportion of dead cells in many tissues.
12. How are the alveoli designs to maximize the exchange of gases?
Ans. The alveoli provide a surface where the exchange of gases can take place. The walls of the alveoli contain an extensive network of blood vessels that helps in maximizing the exchange of gas.
Ans. The alveoli provide a surface where the exchange of gases can take place. The walls of the alveoli contain an extensive network of blood vessels that helps in maximizing the exchange of gas.
13. When a sportsman runs, he often gets muscle cramps. Why?
Ans. When a sportsman runs the rate of consumption of oxygen is more than the rate of supply of oxygen so, in order to fulfill that, the body starts anaerobic respiration. In this process, pyruvic acid converted to lactic acid and it accumulates in the muscles and feels muscle cramps.
Ans. When a sportsman runs the rate of consumption of oxygen is more than the rate of supply of oxygen so, in order to fulfill that, the body starts anaerobic respiration. In this process, pyruvic acid converted to lactic acid and it accumulates in the muscles and feels muscle cramps.
14. What is the adaptation of leaf for photosynthesis?
Ans. Leaves have a large surface area to catch more light from the sun. Leaf contain many chloroplasts that allow light to be converted into chemical energy. It has stomata which are tiny pores present on the surface of the leaves and helps in the exchange of gases. Stomata contain guard cells that control the opening and closing of the pores of the stomata.
Ans. Leaves have a large surface area to catch more light from the sun. Leaf contain many chloroplasts that allow light to be converted into chemical energy. It has stomata which are tiny pores present on the surface of the leaves and helps in the exchange of gases. Stomata contain guard cells that control the opening and closing of the pores of the stomata.
15. Some finger-like projections are present in the inner wall of a small intestine write their names? Why are they important or List their functions?
Ans. Finger-like projections are present in the inner wall of a small intestine are called villi.
The digested food is taken up by the villi and is richly supplied with blood vessels that take the absorbed food to each and every cell of the body, where it is utilised for obtaining energy, building up new tissues and the repair of old tissues.
Ans. Finger-like projections are present in the inner wall of a small intestine are called villi.
The digested food is taken up by the villi and is richly supplied with blood vessels that take the absorbed food to each and every cell of the body, where it is utilised for obtaining energy, building up new tissues and the repair of old tissues.
16. Name the extensively coiled structure of the elementary Canal. Compare the length of the small intestine in herbivores and carnivores.
Ans. The small intestine is the longest part of the elementary canal which is fitted into a compact space because of extensive coiling. The length of the small intestine differs in various animals depending on the food they eat. Herbivores eating grass need a longer small intestine to allow the cellulose to be digested. Meat is easier to digest, hence carnivores like tigers have a shorter small intestine.
Ans. The small intestine is the longest part of the elementary canal which is fitted into a compact space because of extensive coiling. The length of the small intestine differs in various animals depending on the food they eat. Herbivores eating grass need a longer small intestine to allow the cellulose to be digested. Meat is easier to digest, hence carnivores like tigers have a shorter small intestine.
17. List the events that occur during the process of photosynthesis.
Ans. The following events occur during this 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.
Ans. The following events occur during this 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.
18. List the three kinds of blood vessels of the human circulatory system and write their functions in tabular form.
Ans. The three kinds of blood vessels of the human circulatory system are arteries, capillaries, and veins.
Arteries are the vessels that carry blood away from the heart to various organs of the body.
The exchange of material between the blood and surrounding cells takes place across this thin wall of the capillaries. The capillaries then join together to form veins that convey the blood away from the organ or tissue.
Veins collect the blood from different organs and bring it back to the heart.
Ans. The three kinds of blood vessels of the human circulatory system are arteries, capillaries, and veins.
Arteries are the vessels that carry blood away from the heart to various organs of the body.
The exchange of material between the blood and surrounding cells takes place across this thin wall of the capillaries. The capillaries then join together to form veins that convey the blood away from the organ or tissue.
Veins collect the blood from different organs and bring it back to the heart.
19. Name three different glands associated with the digestive system in humans. Also, name their secretions.
Ans. Salivary glands secrete saliva. The saliva 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.
Liver the largest gland secrets bile juice which breaks large globules of fat, down into smaller globules increasing the efficiency of enzyme action.
And third is the pancreas that secrets pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.
Ans. Salivary glands secrete saliva. The saliva 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.
Liver the largest gland secrets bile juice which breaks large globules of fat, down into smaller globules increasing the efficiency of enzyme action.
And third is the pancreas that secrets pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.
20. Why do the walls of the trachea not collapse when there is less air in it.
Ans. The walls of the trachea do not collapse because the trachea is supported by rings of cartilage which hold them in place and provides support to the trachea which does not collapse even when there is less air in it.
Ans. The walls of the trachea do not collapse because the trachea is supported by rings of cartilage which hold them in place and provides support to the trachea which does not collapse even when there is less air in it.
21. What are villi? Explain their functions in the digestive system.
Ans. The inner the lining of the small intestine has numerous finger-like projections called villi which increases the surface area for absorption. The villi are richly supplied with blood vessels that take the absorbed food to each and every cell of the body, where it is utilised for obtaining energy, building up new tissues and the repair of old tissues.
Ans. The inner the lining of the small intestine has numerous finger-like projections called villi which increases the surface area for absorption. The villi are richly supplied with blood vessels that take the absorbed food to each and every cell of the body, where it is utilised for obtaining energy, building up new tissues and the repair of old tissues.
22. Define transpiration. States it's two functions.
Ans. The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration.
Transpiration helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves. It also helps in temperature regulation.
Ans. The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration.
Transpiration helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves. It also helps in temperature regulation.
23. Why do ventricles have thicker muscular walls than atria?
Ans. 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 backward when the atria or ventricles contract.
Ans. 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 backward when the atria or ventricles contract.
24. What is the peristaltic movement?
Ans. The lining of the canal has muscles that contract rhythmically in order to push the food forward. This is called peristaltic movements that occur all along the gut.
It is very important for the movement of food to the stomach and the bowels down the anus.
Ans. The lining of the canal has muscles that contract rhythmically in order to push the food forward. This is called peristaltic movements that occur all along the gut.
It is very important for the movement of food to the stomach and the bowels down the anus.
25. Name the enzymes present in pancreatic juice and give their functions.
Ans. Pancreatic juice contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.
Ans. Pancreatic juice contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.
26. List three characteristics of lungs which make it an efficient respiratory surface.
Ans. Lungs contain balloon-like structure alveoli which provide a surface where the exchange of gases can take place.
The walls of the alveoli contain an extensive network of blood vessels.
The lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for the carbon dioxide to be released.
Ans. Lungs contain balloon-like structure alveoli which provide a surface where the exchange of gases can take place.
The walls of the alveoli contain an extensive network of blood vessels.
The lungs always contain a residual volume of air so that there is sufficient time for oxygen to be absorbed and for the carbon dioxide to be released.
27. Why does the absorption of digested food occur mainly in the small intestine?
Ans. The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption and the digested food is taken up by the walls of the intestine. The villi are richly supplied with blood vessels that take the absorbed food to each and every cell of the body, where it is utilised for obtaining energy, building up new tissues and the repair of old tissues.
Ans. The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption and the digested food is taken up by the walls of the intestine. The villi are richly supplied with blood vessels that take the absorbed food to each and every cell of the body, where it is utilised for obtaining energy, building up new tissues and the repair of old tissues.
28. What is excretion? How do unicellular organisms remove their wastes?
Ans. The biological process involved in the removal of harmful metabolic wastes (gaseous wastes generated during photosynthesis or respiration. Other metabolic activities generate nitrogenous materials) from the body is called excretion.
Ans. The biological process involved in the removal of harmful metabolic wastes (gaseous wastes generated during photosynthesis or respiration. Other metabolic activities generate nitrogenous materials) from the body is called excretion.
29. Name the material transported by the following:
(a) xylem (b) Pulmonary artery (c) Pulmonary veins (d) Phloem.
Ans. (a) Xylem transport water and mineral from the soil through the roots.
(b) The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.
(c) Thew pulmonary veins carry oxygenated blood from the lungs to the heart.
(d) Phloem transports products of photosynthesis from the leaves where they are synthesised to other parts of the plant.
(a) xylem (b) Pulmonary artery (c) Pulmonary veins (d) Phloem.
Ans. (a) Xylem transport water and mineral from the soil through the roots.
(b) The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.
(c) Thew pulmonary veins carry oxygenated blood from the lungs to the heart.
(d) Phloem transports products of photosynthesis from the leaves where they are synthesised to other parts of the plant.
30. Explain the significations of peristaltic movement that occur all along the gut during digestion.
Ans. It is necessary to move the food in a regulated manner along the digestive tube so that it can be processed properly in each part. The lining of the canal has muscles that contract rhythmically in order to push the food forward. This is called peristaltic movements and occurs all along the gut.
Ans. It is necessary to move the food in a regulated manner along the digestive tube so that it can be processed properly in each part. The lining of the canal has muscles that contract rhythmically in order to push the food forward. This is called peristaltic movements and occurs all along the gut.
31. Which mechanism plays an important role in the transportation of water in Plants? (i) during daytime (ii) at night.
Ans. (i) During the day when the stomata are open, the transpiration pull becomes the major driving force in the movement of water in the xylem.
(ii) At night the effect of root pressure in the transport of water is more important.
Ans. (i) During the day when the stomata are open, the transpiration pull becomes the major driving force in the movement of water in the xylem.
(ii) At night the effect of root pressure in the transport of water is more important.
32. Why does the medium become acidic in the mouth? What is the ill effect of this acidic medium? How can this be prevented?
Ans. (i) Bacteria present in the mouth produce acids by the fermentation of sugar and food particles in the mouth.
(ii) The enamel of the tooth gets corroded by the action of acids and tooth decay occurs.
(iii) By cleaning the teeth with toothpaste which is basic in nature and neutralise acids.
Ans. (i) Bacteria present in the mouth produce acids by the fermentation of sugar and food particles in the mouth.
(ii) The enamel of the tooth gets corroded by the action of acids and tooth decay occurs.
(iii) By cleaning the teeth with toothpaste which is basic in nature and neutralise acids.
33. What is translocation? How it takes place in plants?
Ans. The transport of soluble products of photosynthesis is called translocation.
Translocation occurs in the part of the vascular tissue known as phloem. The translocation of food and other substances takes place in the sieve tubes with the help of adjacent companion cells both in upward and downward directions.
34. Name the substrates from the following enzyme:
Trypsin, Amylase, Pepsin, and Lipase.
Ans. The substrate for :
trypsin - is pancreatic juice release from the pancreas.
amylase - is Saliva release from the salivary gland.
pepsin - is protein-digesting enzyme secrets from gastric glands.
lipase - is pancreatic juice release from the pancreas.
35. Why do we feel a cramp in our muscles during certain physical activities?
Ans. During some activities like exercise, running the rate of consumption of oxygen is more than the rate of supply of oxygen so, in order to fulfill that, the body starts anaerobic respiration, which is a process in which respiration takes place in the absence of oxygen. In this process, pyruvic acid converted to lactic acid and it accumulates in the muscles and feels muscle cramps.
1. Why do aquatic animals have a faster rate of breathing compared to terrestrial animals? Name the enzyme present in saliva and state its function.
II. Draw the diagram of the human respiratory system and label the following:
(i) The part where the air is filtered by the fine hair mucus,
(ii) The part which terminates balloon-like structure,
(iii) The balloon-like structure where the exchange of gases takes place,
(iv) The part which separates the chest cavity from the abdominal cavity.
Ans. I. Since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms. Fishes take in water through their mouths and force it past the gills where the dissolved oxygen is taken up by the blood.
Pancreatic juice contains enzymes - trypsin and lipase .
Ans. The transport of soluble products of photosynthesis is called translocation.
Translocation occurs in the part of the vascular tissue known as phloem. The translocation of food and other substances takes place in the sieve tubes with the help of adjacent companion cells both in upward and downward directions.
34. Name the substrates from the following enzyme:
Trypsin, Amylase, Pepsin, and Lipase.
Ans. The substrate for :
trypsin - is pancreatic juice release from the pancreas.
amylase - is Saliva release from the salivary gland.
pepsin - is protein-digesting enzyme secrets from gastric glands.
lipase - is pancreatic juice release from the pancreas.
35. Why do we feel a cramp in our muscles during certain physical activities?
Ans. During some activities like exercise, running the rate of consumption of oxygen is more than the rate of supply of oxygen so, in order to fulfill that, the body starts anaerobic respiration, which is a process in which respiration takes place in the absence of oxygen. In this process, pyruvic acid converted to lactic acid and it accumulates in the muscles and feels muscle cramps.
1. Why do aquatic animals have a faster rate of breathing compared to terrestrial animals? Name the enzyme present in saliva and state its function.
II. Draw the diagram of the human respiratory system and label the following:
(i) The part where the air is filtered by the fine hair mucus,
(ii) The part which terminates balloon-like structure,
(iii) The balloon-like structure where the exchange of gases takes place,
(iv) The part which separates the chest cavity from the abdominal cavity.
Ans. I. Since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms. Fishes take in water through their mouths and force it past the gills where the dissolved oxygen is taken up by the blood.
Pancreatic juice contains enzymes - trypsin and lipase .
The function of trypsin - it helps in digesting proteins.
The function of lipase - it helps in breaking down emulsified fats.
II.
II.
2. Describe the flow of blood through the heart of human beings.
Ans. The heart has different chambers to prevent the oxygen-rich blood from mixing with the blood-containing carbon dioxide. The carbon dioxide-rich blood has to reach the lungs for the carbon dioxide to be removed, and the oxygenated blood from the lungs have to be brought back to the heart.This oxygen-rich blood is then pumped to the rest of 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.
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.
Ans. The heart has different chambers to prevent the oxygen-rich blood from mixing with the blood-containing carbon dioxide. The carbon dioxide-rich blood has to reach the lungs for the carbon dioxide to be removed, and the oxygenated blood from the lungs have to be brought back to the heart.This oxygen-rich blood is then pumped to the rest of 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.
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.
3. Describe the process of urine formation in the kidney.
Ans. The kidney has 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.
Ans. The kidney has 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.
4. Why is blood circulation in the human heart called double circulation?Ans. The blood circulation in the human heart is called double circulation because the blood passes through the heart twice in one complete cycle of the body.
Once - 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.
Second - 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.
What is the advantage of having a four-chambered heart?
Once - 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.
Second - 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.
What is the advantage of having a four-chambered heart?
5. With the help of a schematic flow chart, show the breakdown of glucose in a cell to provide energy:
(i) in the presence of oxygen
(ii) in the absence of oxygen
(iii) when there is a lack of oxygen.
Ans.
(i) in the presence of oxygen
(ii) in the absence of oxygen
(iii) when there is a lack of oxygen.
Ans.
6. I. Name the following:
(i) The process in plants that links light energy with chemical energy
(ii) Organisms that cannot prepare their own food.
(iii) An enzyme secreted from gastric glands in the stomach act on protein.
(iv) Cells that surround a stomatal pore.
(v) The cell organelle where photosynthesis occurs.
II. (i) List two functions performed by dilute hydrochloric acid in our stomach.
(ii) Name the raw materials required for photosynthesis.
Ans. I. (i) Photosynthesis - is the process in plants that links light energy with chemical energy.
(ii) Heterotrophs - that cannot prepare their own food.
(iii) Pepsin, and mucus - a protein-digesting enzyme.
.(iv) Guard cells - that surround the stomata and regulate opening and closing the pores of stomata.
(v) Chloroplasts - the cell organelles contain green pigment chlorophyll and helps in photosynthesis.
II. (i) (a) The hydrochloric acid creates an acidic medium which converts pepsinogen into pepsin or facilitates the action of the enzyme pepsin.
(b) It kills bacteria and harmful organisms that may be present in food.
(ii) Carbon dioxide water sunlight and chlorophyll are the raw materials for photosynthesis.
(i) The process in plants that links light energy with chemical energy
(ii) Organisms that cannot prepare their own food.
(iii) An enzyme secreted from gastric glands in the stomach act on protein.
(iv) Cells that surround a stomatal pore.
(v) The cell organelle where photosynthesis occurs.
II. (i) List two functions performed by dilute hydrochloric acid in our stomach.
(ii) Name the raw materials required for photosynthesis.
Ans. I. (i) Photosynthesis - is the process in plants that links light energy with chemical energy.
(ii) Heterotrophs - that cannot prepare their own food.
(iii) Pepsin, and mucus - a protein-digesting enzyme.
.(iv) Guard cells - that surround the stomata and regulate opening and closing the pores of stomata.
(v) Chloroplasts - the cell organelles contain green pigment chlorophyll and helps in photosynthesis.
II. (i) (a) The hydrochloric acid creates an acidic medium which converts pepsinogen into pepsin or facilitates the action of the enzyme pepsin.
(b) It kills bacteria and harmful organisms that may be present in food.
(ii) Carbon dioxide water sunlight and chlorophyll are the raw materials for photosynthesis.
7. I. Name the following:
(i) Where food is completely digested?
(ii) Juice contains trypsin enzymes.
(iii) Who secretes bile juice?
(iv) That absorbs water from an unabsorbed food.
(v) Two secretions released by a gastric gland.
II. List two major steps involved in the formation of urine and state in brief their functions.
Ans. I. (i) Food is completely digested in the small intestine.
(ii) Pancreatic juice secreted by the pancreas contains trypsin for digesting proteins.
(iii) The liver secretes bile juice to break large fat globules into smaller globules, increasing the efficiency of enzyme action.
(iv) The large intestine absorbs water from unabsorbed food.
(v) Hydrochloric acid and a protein-digesting enzyme called
pepsin.
II. There are three main steps of urine formation:
(i) Filteration of blood- Each kidney has large numbers of filtration units called nephrons that consist of a tubule that is connected with collecting duct at one end a cup-shaped structure at the end and it is called bowmen's capsule. This filtrate contains glucose, amino-acid salts and a major amount of water.
(ii) Reabsorption - Useful substances like glucose, amino acids, salts and a major amount of water are filtered and reabsorbed as the urine flows along the tube.
(iii) Secretion - The urine forming in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder.
(i) Where food is completely digested?
(ii) Juice contains trypsin enzymes.
(iii) Who secretes bile juice?
(iv) That absorbs water from an unabsorbed food.
(v) Two secretions released by a gastric gland.
II. List two major steps involved in the formation of urine and state in brief their functions.
Ans. I. (i) Food is completely digested in the small intestine.
(ii) Pancreatic juice secreted by the pancreas contains trypsin for digesting proteins.
(iii) The liver secretes bile juice to break large fat globules into smaller globules, increasing the efficiency of enzyme action.
(iv) The large intestine absorbs water from unabsorbed food.
(v) Hydrochloric acid and a protein-digesting enzyme called
pepsin.
II. There are three main steps of urine formation:
(i) Filteration of blood- Each kidney has large numbers of filtration units called nephrons that consist of a tubule that is connected with collecting duct at one end a cup-shaped structure at the end and it is called bowmen's capsule. This filtrate contains glucose, amino-acid salts and a major amount of water.
(ii) Reabsorption - Useful substances like glucose, amino acids, salts and a major amount of water are filtered and reabsorbed as the urine flows along the tube.
(iii) Secretion - The urine forming in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder.
8. I. List the role of each of the following in our digestive system.
(i) Muscles of the stomach wall
(ii) Hydrochloric acid.
(iii) Mucus.
II. What is lymph? How is the composition of lymph different from blood plasma? List two functions of the lymphatic system.
Ans. I. (i) Role of muscles of the stomach wall - The stomach is a large organ that expands when food enters it. The muscular walls of the stomach help in mixing the food thoroughly with more digestive juices.
(ii) Role of hydrochloric acid - The gastric glands present in the wall of the stomach that releases hydrochloric acid. The hydrochloric acid creates an acidic medium that facilitates the action of the enzyme pepsin.
(iii) Role of mucus - The mucus that is secreted by the gastric gland, protects the inner lining of the stomach from the action of the acid under normal conditions.
II. Lymph is a tissue fluid that helps in transpiration. Through the pores present in the walls of capillaries, some amount of plasma, proteins and blood cells escape into intercellular spaces in the tissues to form this tissue fluid (Lymph).
It is colourless and contains less protein than blood plasma.
The function of the lymphatic system:
(i) Lymph carries digested and absorbed fat from intestine and
(ii) drains excess fluid from extracellular space back into the blood.
(i) Muscles of the stomach wall
(ii) Hydrochloric acid.
(iii) Mucus.
II. What is lymph? How is the composition of lymph different from blood plasma? List two functions of the lymphatic system.
Ans. I. (i) Role of muscles of the stomach wall - The stomach is a large organ that expands when food enters it. The muscular walls of the stomach help in mixing the food thoroughly with more digestive juices.
(ii) Role of hydrochloric acid - The gastric glands present in the wall of the stomach that releases hydrochloric acid. The hydrochloric acid creates an acidic medium that facilitates the action of the enzyme pepsin.
(iii) Role of mucus - The mucus that is secreted by the gastric gland, protects the inner lining of the stomach from the action of the acid under normal conditions.
II. Lymph is a tissue fluid that helps in transpiration. Through the pores present in the walls of capillaries, some amount of plasma, proteins and blood cells escape into intercellular spaces in the tissues to form this tissue fluid (Lymph).
It is colourless and contains less protein than blood plasma.
The function of the lymphatic system:
(i) Lymph carries digested and absorbed fat from intestine and
(ii) drains excess fluid from extracellular space back into the blood.
9. Give reasons for :
(i) Oxygenated and Deoxygenated blood is separate in the heart of mammals.
(ii) Ventricles are thick-walled.
(iii) Herbivores have longer small intestine as compared to carnivores.
Ans. (i) The separation of the right side and the left side of the heart is useful to keep oxygenated and deoxygenated blood from mixing. Such separation allows a highly efficient supply of oxygen to the body. This is useful in animals that have high energy needs, such as birds and mammals, which constantly use energy to maintain their body temperature.
(ii) 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 backward when the atria or ventricles contract.
(iii) The length of the small intestine differs in various animals depending on the food they eat. Herbivores eating grass need a longer small intestine to allow the cellulose to be digested. Meat is easier to digest, hence carnivores like tigers have a shorter small intestine.
(i) Oxygenated and Deoxygenated blood is separate in the heart of mammals.
(ii) Ventricles are thick-walled.
(iii) Herbivores have longer small intestine as compared to carnivores.
Ans. (i) The separation of the right side and the left side of the heart is useful to keep oxygenated and deoxygenated blood from mixing. Such separation allows a highly efficient supply of oxygen to the body. This is useful in animals that have high energy needs, such as birds and mammals, which constantly use energy to maintain their body temperature.
(ii) 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 backward when the atria or ventricles contract.
(iii) The length of the small intestine differs in various animals depending on the food they eat. Herbivores eating grass need a longer small intestine to allow the cellulose to be digested. Meat is easier to digest, hence carnivores like tigers have a shorter small intestine.
10. Give reasons:
(i) Blood goes only once through the heart in fishes.
(ii) Plants have low energy needs.
(iii) What are capillaries?
Ans. (i) Fishes have only two chambers to their hearts and the blood is pumped to the gills, is oxygenated there, and passes directly to the rest of the body. Thus, blood goes only once through the heart in the fish during one cycle of passage through the body.
(ii) Plants have low energy needs as compared to animals because plants do not move, and plant bodies have a large proportion of dead cells in many tissues.
(iii) On reaching an organ or tissue, the artery divides into smaller and smaller vessels to bring the blood in contact with all the individual cells. The smallest vessels have walls that are one-cell thick and are called capillaries.
(i) Blood goes only once through the heart in fishes.
(ii) Plants have low energy needs.
(iii) What are capillaries?
Ans. (i) Fishes have only two chambers to their hearts and the blood is pumped to the gills, is oxygenated there, and passes directly to the rest of the body. Thus, blood goes only once through the heart in the fish during one cycle of passage through the body.
(ii) Plants have low energy needs as compared to animals because plants do not move, and plant bodies have a large proportion of dead cells in many tissues.
(iii) On reaching an organ or tissue, the artery divides into smaller and smaller vessels to bring the blood in contact with all the individual cells. The smallest vessels have walls that are one-cell thick and are called capillaries.
11. (a) Draw the human excretory system and label the following parts:
(i) left kidney (ii) urinary bladder (iii) vena cava (iv) Urethra (v) Left ureter (vi) Left renal vein (v)left renal artery.
(i) left kidney (ii) urinary bladder (iii) vena cava (iv) Urethra (v) Left ureter (vi) Left renal vein (v)left renal artery.
(b) State the purpose of making urine.
(c) Name any two substances which are selectively reabsorbed from the tubules of the nephron.
(c) Name any two substances which are selectively reabsorbed from the tubules of the nephron.
Ans. (a) Excretory system in human beings:
(b) The purpose of making urine is to filter out waste products from the blood. Nitrogenous waste such as urea or uric acid is removed from blood in the kidneys.
(c) The amount of water reabsorbed depends on:
i. how much excess water there is in the body and
ii. on how much of dissolved waste there is to be excreted.
i. how much excess water there is in the body and
ii. on how much of dissolved waste there is to be excreted.
12. I. Draw a diagram of a cross-section of the human heart and label the following parts :
(i) Right ventricles (ii) Aorta (iii) Left atrium (iv) Pulmonary arteries.
II. Give reasons for the following:
(i) The muscular wall of the ventricles is thicker than the walls of the atria.
(ii) Arteries have thick elastic walls.
Ans. I.
II. (i) Since ventricles have to pump blood into various organs of the body, they have thicker muscular walls than the atria do. valves ensure that blood does not flow backward when the atria or ventricles contract.
(ii) Arteries are the vessels that carry blood away from the heart to various organs of the body. Since the blood emerges from the heart under high pressure, the arteries have thick, elastic walls.
(i) Right ventricles (ii) Aorta (iii) Left atrium (iv) Pulmonary arteries.
II. Give reasons for the following:
(i) The muscular wall of the ventricles is thicker than the walls of the atria.
(ii) Arteries have thick elastic walls.
Ans. I.
(ii) Arteries are the vessels that carry blood away from the heart to various organs of the body. Since the blood emerges from the heart under high pressure, the arteries have thick, elastic walls.
13. Why is the rate of breathing in aquatic organisms much faster than terrestrial organisms?
Ans. Since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, so to take more oxygen, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms.
Fishes take oxygen in water through their mouths and force it past the gills where the dissolved oxygen is taken up by the blood. Terrestrial organisms use oxygen in the atmosphere for respiration. This oxygen is absorbed by different organs in different animals. All these organs have a structure that increases the surface area which is in contact with the oxygen-rich atmosphere
Ans. Since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, so to take more oxygen, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms.
Fishes take oxygen in water through their mouths and force it past the gills where the dissolved oxygen is taken up by the blood. Terrestrial organisms use oxygen in the atmosphere for respiration. This oxygen is absorbed by different organs in different animals. All these organs have a structure that increases the surface area which is in contact with the oxygen-rich atmosphere
14. Why and how does water enter continuously into the root xylem? Why is transpiration important for plants?
Ans. At the roots, cells in contact with the soil actively take up ions. This creates a difference in the concentration of these ions between the root and the soil. Water, therefore, moves into the root from the soil to eliminate this difference. This means that there is a steady movement of water into root xylem, creating a column of water that is steadily pushed upwards.
Transpiration is important for plants because transpiration helps in the absorption of water and upward movement of water and minerals dissolved in it from roots to the leaves. It also helps in temperature regulation.
Ans. At the roots, cells in contact with the soil actively take up ions. This creates a difference in the concentration of these ions between the root and the soil. Water, therefore, moves into the root from the soil to eliminate this difference. This means that there is a steady movement of water into root xylem, creating a column of water that is steadily pushed upwards.
Transpiration is important for plants because transpiration helps in the absorption of water and upward movement of water and minerals dissolved in it from roots to the leaves. It also helps in temperature regulation.
15. I. Name the factors on which the amount of water reabsorbed along the tubular part of the nephron depends on.
II. Draw a diagram of the human excretory system and label the following :
(i) part in which urine is produced
(ii) parts which store the urine
(iii) the part which connects (i) and(ii)
(iv) the part from which urine is passed out. Explain the process of nutrition in amoeba with the help of a diagram.
Ans. I. The amount of water reabsorbed depends on:
i. how much excess water there is in the body, and
ii. on how much of dissolved waste there is to be excreted.
II. See the Long question-answer Q. 11.
II. Draw a diagram of the human excretory system and label the following :
(i) part in which urine is produced
(ii) parts which store the urine
(iii) the part which connects (i) and(ii)
(iv) the part from which urine is passed out. Explain the process of nutrition in amoeba with the help of a diagram.
Ans. I. The amount of water reabsorbed depends on:
i. how much excess water there is in the body, and
ii. on how much of dissolved waste there is to be excreted.
II. See the Long question-answer Q. 11.
16. I. Explain how paramecium obtains its food?
II. Draw a labelled diagram of the human alimentary canal and label the following parts; (i) Liver (ii) Pancreas (iii) Small intestine (iv) Large intestine (v) Oesophagus (vi) Gall bladder (vii) Stomach (viii) Appendix Ans. I. Paramoecium is a unicellular organism, the cell has a definite shape and food is taken in at a specific spot. Food is moved to this spot by the movement of cilia which covers the entire surface of the cell. 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.
II. Diagram of the human alimentary canal :
II. Draw a labelled diagram of the human alimentary canal and label the following parts; (i) Liver (ii) Pancreas (iii) Small intestine (iv) Large intestine (v) Oesophagus (vi) Gall bladder (vii) Stomach (viii) Appendix Ans. I. Paramoecium is a unicellular organism, the cell has a definite shape and food is taken in at a specific spot. Food is moved to this spot by the movement of cilia which covers the entire surface of the cell. 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.
II. Diagram of the human alimentary canal :
17. (a) Draw a diagram of an excretory unit of a human kidney (Nephron) and label the following: Bowman's capsule, glomerulus, collecting duct, tubular part of the nephron, and renal artery.
(b) Write the important functions of the structural and functional unit of the kidney.
(c) Write any one function of an artificial kidney.
Ans. (a)
(b) Write the important functions of the structural and functional unit of the kidney.
(c) Write any one function of an artificial kidney.
Ans. (a)
(b) The structural and functional unit of the kidney is nephron. It is the filtration unit of the kidney. First, the blood reaches the glomerules (consists of a cluster of thin-walled blood capillaries) and then filtrate in bowmen's capsule ( is a cup-shaped end of a tube in which each capillary cluster in the kidney is associated with this and this capsule collects the filtered urine). The filtrate that contains glucose, amino acids, salts and a major amount of water, are selectively re-absorbed as the urine flows along the tube and it gets collected in collecting duct and then stored in the urinary bladder.
(c) An artificial kidney is a device, it removes nitrogenous waste products from the blood through dialysis.
18. I. Explain the mechanism of photosynthesis.
How the transport of materials in xylem and phloem does occur? What is translocation?
II. II. Draw a diagram of a cross-section of a leaf and label the following part:
(i) chloroplast (ii) cuticle.
Ans. I. Mechanism of photosynthesis- Photosynthesis is the process by which plants take in outside substances like carbon dioxide and water and convert them into carbohydrates in the presence of sunlight and chlorophyll.
Chlorophyll is a green pigment and helps to convert the energy of sunlight into chemical energy. During photosynthesis, chlorophyll absorbs energy and then transforms water and carbon dioxide into oxygen and carbohydrates.
Carbohydrates are utilised for providing energy to the plant. The carbohydrates which are not used immediately are stored in the form of starch, which serves as the internal energy reserve to be used as and when required by the plant.
6CO + 6H2O + Chlorophyll + Sunlight → C6H12O6 + O2
( Glucose)
II.
(c) An artificial kidney is a device, it removes nitrogenous waste products from the blood through dialysis.
18. I. Explain the mechanism of photosynthesis.
How the transport of materials in xylem and phloem does occur? What is translocation?
II. II. Draw a diagram of a cross-section of a leaf and label the following part:
(i) chloroplast (ii) cuticle.
Ans. I. Mechanism of photosynthesis- Photosynthesis is the process by which plants take in outside substances like carbon dioxide and water and convert them into carbohydrates in the presence of sunlight and chlorophyll.
Chlorophyll is a green pigment and helps to convert the energy of sunlight into chemical energy. During photosynthesis, chlorophyll absorbs energy and then transforms water and carbon dioxide into oxygen and carbohydrates.
Carbohydrates are utilised for providing energy to the plant. The carbohydrates which are not used immediately are stored in the form of starch, which serves as the internal energy reserve to be used as and when required by the plant.
6CO + 6H2O + Chlorophyll + Sunlight → C6H12O6 + O2
( Glucose)
II.
19. In human alimentary canal name the site of the complete digestion of various components of food. Explain the process of digestion.
Ans. The small intestine is the site of the complete digestion of carbohydrates, proteins, and fats. It receives the secretions of the liver and pancreas.
The pancreas secretes pancreatic juice which contains enzymes like trypsin for digesting proteins and lipase for breaking down emulsified fats.
The liver secretes bile juice break fats that are present in the intestine in the form of large globules. The walls of the small intestine contain glands that secrete intestinal juice which convert the proteins to amino acids, complex carbohydrates into glucose and fats into fatty acids and glycerol. The digested food is taken up by the walls (contain villi)of the intestine where it is utilised for obtaining energy, building up new tissues and the repair of old tissues. The unabsorbed food is sent into the large intestine.
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