CBSE · NCERT · Class 7 Science · Chapter 1

NCERT Solutions: Class 7 Science Chapter 1 - Nutrition in Plants

12 textbook Q&A12 verifiedFree Content

Chapter-wise NCERT intext questions and exercise answers for Nutrition in Plants, grounded in the official textbook.

Questions are taken verbatim from the NCERT textbook; answers were grounded against the chapter's content during generation. Items needing review are marked.
Sections in this chapter
Exercises 12
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1Exercises12 questions
Q.1Why do organisms need to take food?v
Answer:

Organisms need food to obtain energy for life processes, to grow, to repair damaged body parts and to maintain health. Food also supplies the materials needed for building the body.

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Q.2Distinguish between a parasite and a saprotroph.v
Answer:

A parasite derives nutrition from a living host and usually harms it, for example Cuscuta. A saprotroph obtains nutrition from dead and decaying matter by secreting digestive juices on it and absorbing the dissolved nutrients, for example fungi.

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Q.3How would you test the presence of starch in leaves?v
Answer:

Put a few drops of iodine solution on a leaf. If starch is present, the part of the leaf containing starch turns blue-black.

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Q.4Give a brief description of the process of synthesis of food in green plants.v
Solution

In word form: carbon dioxide and water, in the presence of sunlight and chlorophyll, form carbohydrates and oxygen.

Answer:

Green plants make food by photosynthesis. Leaves take carbon dioxide from air through stomata and water is brought from the soil by roots. Chlorophyll in the leaves captures sunlight and uses its energy to make carbohydrates. Oxygen is released during the process.

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Q.5Show with the help of a sketch that plants are the ultimate source of food.v
Solution

Place green plants at the start of a food chain and show all animals depending on them directly or indirectly.

Answer:

Draw a food chain beginning with a green plant. For example: grass/green plants $\rightarrow$ deer/goat/cow $\rightarrow$ lion/human. The sketch should show that herbivores get food directly from plants and carnivores get food indirectly from plants through herbivores. Thus, plants are the ultimate source of food.

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Q.6Fill 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 captured by the pigment called ___________. (d) During photosynthesis plants take in ______________________ and release __________________ gas.v
Answer:

(a) autotrophs
(b) starch
(c) chlorophyll
(d) carbon dioxide; oxygen

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Q.7Name 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.v
Answer:

(i) Dodder or Cuscuta
(ii) Pitcher plant
(iii) Stomata

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Q.8Tick 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) rosev
  1. a. autotroph / parasite / saprotroph / host
  2. b. Cuscuta / china rose / pitcher plant / rose
Answer:

(a) (ii) parasite
(b) (iii) pitcher plant

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Q.9Match the items given in Column I with those in Column II: Column I: Chlorophyll, Nitrogen, Cuscuta, Animals, Insects. Column II: Rhizobium, Heterotrophs, Pitcher plant, Leaf, Parasite.v
Answer:

Chlorophyll - Leaf; Nitrogen - Rhizobium; Cuscuta - Parasite; Animals - Heterotrophs; Insects - Pitcher plant.

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Q.10Mark '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)v
Solution

Oxygen, not carbon dioxide, is released during photosynthesis. Food-making plants are autotrophs. Photosynthesis mainly produces carbohydrates, and sunlight is stored as chemical energy in food.

Answer:

(i) F
(ii) F
(iii) T
(iv) T

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Q.11Choose 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) Sepalsv
  1. a. Root hair
  2. b. Stomata
  3. c. Leaf veins
  4. d. Sepals
Solution

Stomata are tiny pores on the leaf surface through which gaseous exchange takes place.

Answer:

(ii) Stomata

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Q.12Choose the correct option from the following: Plants take carbon dioxide from the atmosphere mainly through their: (i) roots (ii) stem (iii) flowers (iv) leavesv
  1. a. root
  2. b. stem
  3. c. leaf
  4. d. flower
Solution

Leaves have stomata, which take in carbon dioxide needed for photosynthesis.

Answer:

(iv) leaves

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