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Practice each question, then open the answer or worked solution.
Why do organisms take food?
All organisms require energy for their life processes. Plants prepare their food and acquire nutrients from abiotic components like soil, air, water and sunlight. On the other hand, animals need to get food from either plants or other animals to obtain nutrients; hence, animals need to take food to acquire nutrients and energy.
Distinguish between a parasite and a saprophyte.
| Saprophytes | Parasites |
| Acquire nutrients from dead and decaying matter. | Parasites live on or in a host and get their food at the expense of their host. |
| Example: Fungi | Example: Roundworm |
How would you test the presence of starch in leaves?
Take two potted plants of the same kind. Keep one in the dark for 72 hours and the other in the sunlight. Perform the iodine test with the leaves of both plants as given below. Now, leave the pot, which was earlier kept in the dark, undisturbed for 3–4 days and perform the iodine test again on its leaves.
Iodine test:
Put iodine solution on the leaf.
Observation:
Blue-black colour will be observed on the leaves of the plant kept in sunlight, which indicates the presence of starch.
Blue-black colour will not be observed on the leaves of plants kept in the darkroom. This indicates the absence of starch.
Give a brief description of the process of synthesis of food in green plants.
Green plants use a process called photosynthesis to prepare their food. The process is as follows
Show with the help of a sketch that plants are the ultimate source of food.
Fill in the blanks.
(a) Green plants are called _________________ since they synthesise their own food.
(b) The food synthesised by plants is stored as _________________.
(c) In photosynthesis, solar energy is absorbed by the pigment called ___________.
(d) During photosynthesis, plants take in ______________________ and release __________________ gas.
(a) Green plants are called autotrophs since they synthesise their food.
(b) The food synthesised by plants is stored as starch.
(c) In photosynthesis, solar energy is absorbed by the pigment called chlorophyll.
(d) During photosynthesis, plants take in carbon dioxide and release oxygen gas.
Name the following.
i) A parasitic plant with a yellow, slender and branched stem.
ii) A plant that is partially autotrophic.
iii) The pores through which leaves exchange gases.
i) Cuscuta
ii) Pitcher plant
iii) Stomata
Tick the correct answer.
(a) Cuscuta 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
(a) (ii) Parasite
(b) (iii) pitcher plant
Match the items given in Column I with those in Column II.
| Column-I | Column-II |
| Chlorophyll | Rhizobium |
| Nitrogen | Heterotrophs |
| Cuscuta | Pitcher plant |
| Animals | Leaf |
| Insects | Parasite |
| Column-I | Column-II |
| Chlorophyll | Leaf |
| Nitrogen | Rhizobium |
| Cuscuta | Parasite |
| Animals | Heterotrophs |
| Insects | Pitcher plant |
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)