Solution of Chapter 15. Plant Growth and Development (Biology NCERT Book)

12 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, You forget to add cytokinin to the culture medium.

1 Define growth, differentiation, development, dedifferentiation, redifferentiation , determinate growth, meristem and growth rate.

2 Why is not any one parameter good enough to demonstrate growth throughout the life of a flowering plant?

4  (a) Arithmetic growth(b) Geometric growth(c) Sigmoid growth curve(d) Absolute and relative growth rates. 

5 List five main groups of natural plant growth regulators. Write a note of discovery, physiological functions and agricultural / horticultural applications of any one of them.

6 What do you understand about photoperiodism and vernalisation? Describe their significance.

7 Why is abscisic acid also known as stress hormone?

8 "Both growth and differentiation in higher plants are ‘open’" Comment.

9 "Both a short day plant and a long day plant produce flower simultaneously in a given place"- Explain.

10 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. 

11 Would a defoliated plant respond to photoperiodic cycle? Why?