1 NUTRITION IN PLANTS TEXTBOOK QUESTIONS AND ANSWERS Q.1. How do plants prepare their own food? Ans. In plants, water and minerals present in the soil are absorbed by roots and transported to leaves. Carbon dioxide from, air is taken in through the stomata, present on the surface of leaves. The leaves have green pigment called chlorophyll, which help it to capture the energy of the sunlight. So, leaves of green plants containing chlorophyll synthesize carbohydrates in the presence of sunlight, water and carbon dioxide. COB2B + HB2BO Sunlight chlorophyll Carbohydrate + water. Q.2. Why our body cannot make food from the carbon dioxide, water and minerals like plants do? Ans. Our body cannot make food from the carbon dioxide, water and minerals like plants do because our body has no chlorophyll which helps to capture the energy of the sunlight. This energy is used to synthesize food from carbon dioxide and water. 1
Q.3. How water and minerals absorbed by roots reach the leaves? Ans. Water and minerals are transported to the leaves by the vessels which run like pipes throughout the root, stem, branches and the leaves. They form a continuous path or passage for the nutrients to reach the leaf. Q.4. What is so special about the leaves that they can synthesize food but other parts of the plant cannot? Ans. The leaves have a green pigment called chlorophyll which helps leaves to capture the energy of the sunlight. Other parts of the plant do not have chlorophyll. Q.5. Some plants have deep red, violet or brown leaves. Can these leaves also carry out photosynthesis? Ans. Yes, these leaves can carry out the process of photosynthesis because they also contain chlorophyll. The large amount of red, violet and brown pigment mask the green colour of chlorophyll. Q.6. Are mosquitoes, bed bugs, lice and leeches that suck our blood also parasites? Ans. Yes. 2
Q.7. If the pitcher plant is green and carries out photosynthesis, then why does it feed on insects? Ans. Because the pitcher plant does not get all the required nutrients from the soil in which it grows. Q.8. Some animals do not have mouths like other animals. They are not like green plants as they lack chlorophyll and cannot make food by photosynthesis. How do these organisms acquire nutrients? Ans. These organisms secrete digestive juices on the dead and decaying matter and convert it into a solution. Then they absorb the nutrients form it. Q.9. Paheli s beautiful shoes, which she wore on special occasion, were spoiled by fungi during the rainy season. She wants to know how fungi appear suddenly during the rainy season. Ans. Fungi grow on articles that are left in hot and humid weather for a long time. The fungal spores are generally present in the air. During the rainy season, they land on wet and warm things and then germinate and grow. Q.10. Do fungi cause disease also? Ans. Yes, fungi cause diseases in plants, animals and humans. 3
TEXT BOOK EXERCISES AND ANSWERS PAGE NO. 9 Q.1. Why do organisms need to take food? Ans. Food is needed by all living organisms for different purposes 1. All living organisms take food and utilize it to get energy for growth and maintenance of their bodies. 2. Another important function of food is to provide energy to carry out life - processes. 3. Food is also needed by living beings for replacement and repairing their damaged parts. 4. Food gives us resistance against diseases and protect us from infections. Q.2. Distinguish between a parasite and a saprotroph. Ans. Parasite A parasite takes readymade food from the organism on which it feeds. Saprotroph They secrete digestive juices on the matter they live and convert it into a solution and then absorb it. 4
2. They feed on living organisms. 3. The organism on which it feeds is called host. 4. It deprives the host of valuable nutrients. They feed on dead and decaying organisms. They do not feed on living organism. There is no host at all. Q.3. How would you test the presence of starch in leaves? Ans. Presence of starch in leaves can be tested by iodine test. Iodine turns starch solution blue-black. Pour few drops of dilute iodine solution on the leaf. The leaf becomes blue-black which proves the presence of starch in it. Q.4. Give a brief description of the process of synthesis of food in green plants. Ans. The synthesis of food in plants occurs in leaves. The leaves have a green pigment called chlorophyll. It helps leaves to capture the energy of the sunlight. This energy is used to synthesize food from carbon dioxide and water. Thus, chlorophyll, sunlight, carbon dioxide and water help to carry out the process of photosynthesis. The solar energy captured by the leaves is stored in the plant in the form of food. 5
Carbon dioxide + water Sunlight chlorophyll Carbohydrate + oxygen. Q.5. Show with the help of a sketch that the plants are the ultimate source of food. Ans. Plants Herbivores Carnivores SAPROPHYTES Plants (The ultimate source of food) Q.6. Fill in the blanks : (a) Green plants are called since they synthesis synthesise their own food. (b) The food synthesised by the plants is stored as. (c) In photosynthesis, solar energy is captured by the pigment called. (d) During photosynthesis plants take in and release. 6
Ans. (a) autotrophs, (b) starch (c) chlorophyll, (d) carbon dioxide, oxygen. Q.7. Name the following : (i) A parasitic plant with yellow, slender and tubular stem. (ii) A plant that has both autotrophic and heterotrophic mode of nutrition. (iii) The pores through which leaves exchange gases. Ans. (i) Cuscuta (Amarbel), (ii) Insectivorous plant, (iii) Stomata. Q.8. Tick the correct answer : (a) Amarbel is an example of : (i) Autotroph, (ii) Parasite, (iii) Saprotroph, (iv) host Ans. (ii) Parasite. (b) The plant which traps and feeds on insects is : (i) cuscuta, (ii) china rose, (iii) pitcher plant, (iv) rose Ans. (iii) Pitcher plant. 7
Q.9. Match the items given in column I with those in column II : Column I Chlorophyll Nitrogen Amarbel Animals Insects Column II Bacteria Heterotrophs Pitcher plant Leaf Parasite Ans. Column I Chlorophyll Nitrogen Amarbel Animals Insects Column II Leaf Bacteria Parasite Heterotrophs Pitcher plant Q.10. Mark T if the statement is true and F if it is false: Ans. False (i) Carbon dioxide is released during photosynthesis. (T/F) 8
(ii) Plants which synthesise their food themselves are called saprotrophs. (T/F) (iii) The product of photosynthesis is not a protein. (T/F) Ans. True. (iv) Solar energy is converted into chemical energy during photosynthesis. (T/F) Ans. True. Q.11. Choose the correct option from the following : Which part of the plant gets carbon dioxide from the air for photosynthesis. (i) root hair (ii) stomata (iii) leaf veins (iv) sepals Ans. (ii) Stomata. Q.12. Choose the correct option from the following : Plants take carbon dioxide from the atmosphere mainly through their : (i) roots (ii) stem (iii) flowers (iv) leaves Ans. (iv) Leaves. 9
EXTENDED LEARNING ACTIVITIES AND PROJECTS 1. Project Take a potted plant with broad leaves. Take two strips of black paper and cut out a small square in their centres. Cover a part of two leaves with these paper and secure them with paper clips. Keep the plant in the sunlight for 2-5 days. Observe the difference in the colour of the covered and the uncovered portions on the one leaf. Perform iodine test on this leaf. Did the two parts show any difference in results? Now, take another leaf. Remove the strip and expose the covered part to the sunlight for 2-3 days and do the iodine test again. Describe your observations. Ans. (i) The covered part will turn pale, whereas the uncovered part will be bright green in colour. (ii) The covered part on testing with iodine solution does not turn blue black, whereas the uncovered part turns blue black on testing with iodine solution showing the presence of starch. If the covered part is removed of the strip and exposed to sunlight for 2 to 3 days and tested with iodine solution it will turn blue black (showing the presence of starch). 10