17. Plant parts show two types of movements, one dependent on growth and the other independent of growth. Give one example of the movement in plant parts:

(a) which depends on growth

(b) which does not depend on growth

18. What is a plant hormone? Name four plant hormones. State one function of each.

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19. (a) What does a root do in response to gravity? What is this phenomenon known as?

(b) What does a stem (or shoot) do in response to light? What is this phenomenon known as?

20. (a) What does a stem (or shoot) do in response to gravity? What is this phenomenon known as?

(b) What does a root do in response to light? What is this phenomenon known as?

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21. (a) What does a Mimosa pudica plant do in response to touch? What is this phenomenon known as?

(b) What happens to the dandelion flower (i) during daytime, and (ii) at night? What is this phenomenon known as?

22. (a) What does a plant root do in response to water? What is this phenomenon known as?

(b) What happens to the moonflower (i) during daytime, and (ii) at night? What is this phenomenon known as?

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23. What is a tendril? Name the two types of tendrils. What does a tendril do in response to the touch of a support? What is this phenomenon known as?

24. Name the five types of tropisms. How are tropic movements helpful to plants? Explain with an example.

25. Define chemotropism. Give one example of chemotropism. State whether this example is of positive chemotropism or negative chemotropism.

26. Distinguish between tropic movements and nastic movements in plants. Give examples to illustrate your answer.

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27. (a) What is meant by nastic movements in plants? Give one example of nastic movements in plants. (b) What is the difference between photonasty and thigmonasty?

28. A potted plant is kept horizontally for a considerable time. The three positions of the parts A and B of the potted plant are shown in the following figures:

(a) Which figure shows the correct position taken by the parts A and B of the plant?

(b) What type of phenomenon is exhibited by the figure chosen in (a) above?

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29. Name the plant hormones which are responsible for the following effects:

(a) falling of leaves (b) opening of stomata

(c) bending of stem towards light (d) closing of stomata

30. Name the plants organs which are:

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(a) positively phototrophic (b) positively geotropic

(c) negatively geotropic (d) positively hydrotropic

31. Why is the folding up of the leaves of a sensitive plant on touching with a finger not a tropism?

32. Why is the closing of a dandelion flower at dusk (when it gets dark) not a tropism?

Answers:

17. (a) Bending of stem (or shoot) towards light (b) Folding up of the leaves of a sensitive plant on touching 19. (a) Root bends downwards in the direction of gravity ; Positive geotropism (b) Stem (or shoot) bends towards the light; Positive phototropism; 20. (a) Stem (or shoot) grows upward against the direction of gravity; Negative geotropism (b) Root bends away from light; Negative phototropism 28. (a) Figure (ii) (b) Geotropism 29. (a) Abscisic! acid (b) Cytokinin (c) Auxin (d) Abscisic acid 30. (a) Stem (or Shoot) (b) Root (c) Stem (or Shoot) (d) Root