NCERT Class VII: Science-Exercise Solutions

Chapter 01-Nutrition in Plants-Exercise Solutions

NCERT Book Page Number-9
Q.1. Why do organisms need to take food?
Answer: Food is needed by all living organisms for the following purposes :
It is meant for the general growth and development of an organism. If it is not in sufficient amount, then it shows insufficient growth and development, along with hunger sign.
It is meant to provide energy. We need energy for movements such as running, walking or raising our arm.
It is also needed by living beings for repairing of their damaged parts.
It gives us resistance against diseases and protects us from infections.
Q.2. Distinguish between a parasite and a saprotroph.
Answer:


Q.3. How would you test the presence of starch in leaves?
Answer: The presence of starch in leaves can be tested by ‘Iodine Test’. Iodine turns starch solution into blue-black colour.
Q.4. Give a brief description of the process of synthesis of food in green plants.
Answer: Leaves of a plant have a green pigment called chlorophyll. In the presence of sunlight, they use carbon dioxide and water to synthesise carbohydrate.
Carbon dioxide + Water $\rightarrow$ Carbohydrade + Water + Oxygen
During the process, oxygen is released. The carbohydrates ultimately get converted into starch.
Carbon dioxide from air is taken through stomata. Water and minerals are absorbed by the roots and transported to the leaves.
Q.5. Show with the help of a sketch that plants are the ultimate source of food.
Answer:


Fig. Plants capture solar energy by a unique process called photosynthesis
Q.6. Fill in the blanks:
(a) Green plants are called …….. since they 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 ……….
Answer:
(a) autotrophs
(b) starch
(c) chlorophyll
(d) carbon dioxide, oxygen
Q.7. Name the following:
(i) A parasitic plant with yellow, slender and branched stem.
(i) A plant that is partially autotrophic.
(iii) The pores through which leaves exchange gases.
Answer:
(i) Cuscuta
(ii) Insectivorous plants
(iii) Stomata
Q.8. Tick the correct answer:
(a) Amarbel is an example of:
(i) Autotroph
(ii) Parasite
(iii) Saprotroph
(iv) Host
(b) The plant which traps and feeds on insects is:
(i) Cuscuta
(ii) China rose
(iii) Pitcher plant
(iv) Rose
Answer:
(a) Amarbel is an example of:
(i) Autotroph
(ii) Parasite $(\checkmark)$
(iii) Saprotroph
(iv) Host
(b) The plant which traps and feeds on insects is:
(i) Cuscuta
(ii) China rose
(iii) Pitcher plant $(\checkmark)$
(iv) Rose
Q.9. Match the items given in Column I with those in Column II.


Answer:


Q.10. Mark T if the statement is true and ‘F’ if it is false:
(i) Carbon dioxide is released during photosynthesis. (T/F)
(ii) Plants which synthesise their food are called saprotrophs. (T/F)
(iii) The product of photosynthesis is not a protein. (T/F)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F)
Answer:
(i) F
(ii) F
(iii) T
(iv) T
NCERT Book Page Number-10
Q.11. Choose the correct option from the following:
Which part of the plant takes in carbon dioxide from the air for photosynthesis?
(i) Root hair
(ii) Stomata
(iii) Leaf veins
(iv) Petals
Answer:
(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
Answer:
(iv) leaves
Q.13. Why do farmers grow many fruits and vegetable crops inside large green houses? What are the advantages to the farmers?
Answer: Most of the crops require a lot of nitrogen to make protein. After the harvest, the soil becomes deficient in nitrogen. Though nitrogen gas is available in air, plants cannot use it directly. They need nitrogen in a soluble form. The bacterium called rhizobium can take atmospheric nitrogen and convert it into a soluble nitrogenous components. Rhizobium is present in the roots of some fruits and vegetables and legumes plants which provides nitrogen to them. By crop rotation, farmers increase the nitrogenous compounds in soil. So there is no need to add nitrogenous fertilisers to the soil in which leguminous plants are grown. By this practice farmers provide the good quality of crops and save the money.