Class 11 Biology - Chapter Plant Growth and Development NCERT Solutions | Why is Abscisic acid also known as stres
Why is Abscisic acid also known as stress hormone?
Abscisic acid is called stress hormones as it induces various responses in plants against stress conditions.
It increases the tolerance of plants toward various stresses. It induces the closure of the stomata during water stress. It promotes seed dormancy and ensures seed germination during favourable conditions. It helps seeds withstand desiccation. It also helps in inducing dormancy in plants at the end of the growing season and promotes abscission of leaves, fruits, and flowers.
More Questions From Class 11 Biology - Chapter Plant Growth and Development
- Q:- What would be expected to happen if:
(a) GA3 is applied to rice seedlings
(b) Dividing cells stop differentiating
(c) A rotten fruit gets mixed with unripe fruits
(d) You forget to add cytokinin to the culture medium. - Q:- Describe briefly:
(a) Arithmetic growth
(b) Geometric growth
(c) Sigmoid growth curve
(d) Absolute and relative growth rates - Q:- What do you understand by photoperiodism and vernalisation? Describe their significance.
- Q:- Which one of the plant growth regulators would you use if you are asked to:
(a) Induce rooting in a twig
(b) Quickly ripen a fruit
(c) Delay leaf senescence
(d) Induce growth in axillary buds
(e) Bolt a rosette plant
(f) Induce immediate stomatal closure in leaves. - Q:- List five main groups of natural plant growth regulators. Write a note on discovery, physiological functions and agricultural/horticultural applications of any one of them.
- Q:- Both a short day plant and a long day plant can flower simultaneously in a given place. Explain.
- Q:- Both growth and differentiation in higher plants are open. Comment.
- Q:- Would a defoliated plant respond to photoperiodic cycle? Why?
- Q:- Define
(a) Growth
(b) Differentiation
(c) Development
(d) De differentiation
(e) Re differentiation
(f) Determinate growth
(g) Meristem
(h) Growth rate. - Q:- Why is not any one parameter good enough to demonstrate growth throughout the life of a flowering plant?
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Which of the following is not correct?
(a) Robert Brown discovered the cell.
(b) Schleiden and Schwann formulated the cell theory.
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(d) A unicellular organism carries out its life activities within a single cell. - Q:- What are macromolecules? Give examples.
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