Below are the NCERT Solutions for Class 7 Science Chapter 1: Nutrition in Plants, designed to help students understand the concepts more effectively. These solutions are prepared by expert teachers following the latest CBSE Class 7 Science syllabus. Regular practice is essential for students to excel in their Class 7 examinations.
NCERT Solution for Class 7 Science Chapter 1 - Nutrition in Plants
Exercise Questions with Answers
1. Why do organisms take food ?
Solution :
All organisms need energy for their life processes. Plants produce their food and obtain nutrients from abiotic components such as soil, air, water, and sunlight. In contrast, animals must obtain their food from either plants or other animals to get the necessary nutrients and energy. Therefore, animals rely on consuming food to acquire the nutrients and energy they need.
2. Distinguish between a parasite and a saprotroph.
Solution :
Saprotroph obtain nutrients from dead and decaying matter. An example of a saprophyte is fungi.
Parasites live on or in a host and obtain their food at the host's expense. An example of a parasite is the roundworm.
3. How would you test the presence of starch in leaves ?
Solution :
Take two potted plants of the same kind. Place one in the dark for 72 hours and the other in the sunlight. Perform the iodine test on the leaves of both plants as described below. Then, leave the pot that was kept in the dark undisturbed for 3–4 days in the sunlight, and perform the iodine test again on its leaves.
Iodine Test : Put Iodine Solution on the leaf.
Observation :
A blue-black color will be observed on the leaves of the plant kept in sunlight, indicating the presence of starch.
In contrast, a blue-black color will not be observed on the leaves of the plant kept in the dark room, indicating the absence of starch.
4. Give the brief description of the process of synthesis of food in green plants.
Solution :
Green plants use a process called photosynthesis to prepare their food. The process is as follows:
1. Water is absorbed by the roots of the plant and transported to the leaves.
2. Carbon dioxide from the air enters the leaves through pores called stomata. This gas diffuses into the cells containing chlorophyll.
3. Water molecules are broken down into hydrogen and oxygen with the help of sunlight.
4. Hydrogen combines with carbon dioxide to form carbohydrates.
Photosynthesis can be represented by the following equation :
This equation shows that six molecules of carbon dioxide and six molecules of water, using energy from sunlight, are converted into one molecule of glucose and six molecules of oxygen.
5. Show with the help of a sketch that plants are the ultimate source of food.
Solution :
6. 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.
Solution :
(a) autotrophs
(b) starch
(c) chlorophyll
(d) carbon dioxide, oxygen
7. Name the following :
(i) A parasitic plant with yellow, slender and branched stem.
(ii) A plant that is partially autotrophic.
(iii) The pores through which leaves exchange gases.
Solution :
(i) Cuscuta
(ii) insectiorous plant
(iii) stomata
8. Tick the correct answer :
(a) Cuscata is an example of :
(i) autotroph
(ii) parasite
(iii) saprotroph
(iv) host
Solution :
(ii) parasite
(b) The plant which traps and feed on insects is :
(i) Cuscata
(ii) china rose
(iii) pitcher plant
(iv) rose
Solution :
(iii) pitcher plant
9. Match the items given in Column I with those in Column II :
| Column I | Column II |
|---|---|
| Chlorophyll | Rhizobium |
| Nitrogen | Hetrotrophs |
| Cuscuta | Pitcher Plant |
| Animals | Leaf |
| Insects | Parasite |
Solution :
| Column I | Column II |
|---|---|
| Chlorophyll | Leaf |
| Nitrogen | Rhizobium |
| Cuscuta | Parasite |
| Animals | Heterotrophs |
| Insects | Pitcher plant |
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)
Solution :
(i) False (ii) False (iii) True (iv) True
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
Solution :
(ii) Stomata
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
Solution :
(iv) leaves
13. Why do farmers grow many fruits and vegetable inside large green houses ? What are the advantages to the farmers ?
Solution :
Fruits and vegetable crops are cultivated in large greenhouses to shield them from external climatic conditions and to provide an optimal temperature for growth.
Advantages for farmers when growing fruits and vegetable crops inside greenhouses include:
- Protection of crops from diseases and adverse climatic conditions.
- Safeguarding of crops from wind and rodents.