Plant Physiology

Samacheer Book Back Questions And Answers For Science Standard 9 “Plant Physiology“

I. Choose the correct answer:
1. The tropic movement that helps the climbing vines to find a suitable support is _____.
(a) Phototropism
(b) Geotropism
(c) Thigmotropism
(d) Chemotropism

2. The chemical reaction occurs during photosynthesis is _____.
(a) CO₂ is reduced and water is oxidized
(b) water is reduced and CO₂ is oxidized
(c) both CO₂ and water are oxidized
(d) both CO₂ and water are produced

3. The bending of root of a plant in response to water is called _____.
(a) Thigmonasty
(b) Phototropism
(c) Hydrotropism
(d) Photonasty

4. A growing seedling is kept in the dark room. A burning candle is placed near it for a few days. The tip part of the seedling bends towards the burning candle. This is an example of _____.
(a) Chemotropism
(b) Geotropism
(c) Phototropism
(d) Thigmotropism

5. The root of the plant is _____.
i) positively phototropic but negatively geotropic
ii) positively geotropic but negatively phototropic
iii) negatively phototropic but positively hydrotropic
iv) negatively hydrotropic but positively phototropic
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)

6. The non-directional movement of a plant part in response to temperature is called _____.
(a) Thermotropism
(b) Thermonasty
(c) Chemotropism
(d) Thigmonasty

7. Chlorophyll in a leaf is required for _____.
(a) photosynthesis
(b) tropic movement
(c) transpiration
(d) nastic movement

8. Transpiration takes place through _____.
(a) fruit
(b) seed
(c) flower
(d) stomata

II. Fill in the blanks:
1. The shoot system grows upward in response to _____.
2. _____ is positively hydrotropic as well as positively geotropic.
3. The green pigment present in the plant is _____.
4. The solar tracking of sunflower in accordance with the path of sun is due to _____.
5. The response of a plant part towards gravity is _____.
6. Plants take in carbon dioxide for photosynthesis but need _____ for their living.

Answers:
1. light
2. root
3. chlorophyll
4. phototropism
5. geotropism
6. oxygen

III. Match the following:
1. Roots growing downwards into soil                A. Positive phototropism
2. Shoots growing towards the light                   B. Negative geotropism
3. Shoots growing upward                                  C. Negative phototropism
4. Roots growing downwards away from light    D. Positive geotropism

Answers:
1. D
2. A
3. B
4. C

IV. State whether true or false. If false, correct the statement:
1. The response of a part of plant to the chemical stimulus is called phototropism.
2. Shoot is positively phototropic and negatively geotropic.
3. When the weather is hot, water evaporates lesser which is due to opening of stomata.
4. Photosynthesis produces glucose and carbon dioxide.
5. Photosynthesis is important in releasing oxygen to keep the atmosphere in balance.
6. Plants lose water when the stomata on leaves are closed.

Answers:
1. False (The response of a plant part to the chemical stimulus is called Chemotropism)
2. True
3. False (When the weather is hot, water evaporates more but stomata begin to close to reduce evaporation)
4. False (Photosynthesis produces glucose and oxygen)
5. True
6. False (Plants lose water when the stomata on leaves are open)

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