NCERT Solutions for Class 11 Biology Chapter 15

Plant Growth and Development Class 11

Chapter 15 Plant Growth and Development Exercise Solutions

<< Previous Chapter 14 : Respiration in Plants Next Chapter 16 : Digestion and Absorption >>

Exercise : Solutions of Questions on Page Number : 253

Q1 :  

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


Answer :

(a) Growth

It is an irreversible and permanent process, accomplished by an increase in the size of an organ or organ parts or even of an individual cell.

(b) Differentiation

It is a process in which the cells derived from the apical meristem (root and shoot apex) and the cambium undergo structural changes in the cell wall and the protoplasm, becoming mature to perform specific functions.

(c) Development

It refers to the various changes occurring in an organism during its life cycle - from the germination of seeds to senescence.

(d) De-differentiation

It is the process in which permanent plant cells regain the power to divide under certain conditions.

(e) Re-differentiation

It is the process in which de-differentiated cells become mature again and lose their capacity to divide.

(f) Determinate growth

It refers to limited growth. For example, animals and plant leaves stop growing after having reached maturity.

(g) Meristem

In plants, growth is restricted to specialised regions where active cell divisions take place. Such a region is called meristem. There are three types of meristems - apical meristem, lateral meristem, and intercalary meristem.

(h) Growth rate

It can be defined as the increased growth in plants per unit time.

Answer needs Correction? Click Here

Q2 :  

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


Answer :

In plants, growth is said to have taken place when the amount of protoplasm increases. Measuring the growth of protoplasm involves many parameters such as the weight of the fresh tissue sample, the weight of the dry tissue sample, the differences in length, area, volume, and cell number measured during the growth period. Measuring the growth of plants using only one parameter does not provide enough information and hence, is insufficient for demonstrating growth.

Answer needs Correction? Click Here

Q3 :  

Describe briefly:

(a) Arithmetic growth

(b) Geometric growth

(c) Sigmoid growth curve

(d) Absolute and relative growth rates


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q4 :  

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.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q5 :  

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


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q6 :  

Why is Abscisic acid also known as stress hormone?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q7 :  

'Both growth and differentiation in higher plants are open'. Comment.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q8 :  

'Both a short day plant and a long day plant can flower simultaneously in a given place'. Explain.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q9 :  

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.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q10 :  

Would a defoliated plant respond to photoperiodic cycle? Why?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q11 :  

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.


Answer :

Please Register/Login to get access to all solutions Facebook Login
<< Previous Chapter 14 : Respiration in Plants Next Chapter 16 : Digestion and Absorption >>

Biology : CBSE NCERT Exercise Solutions for Class 11th for Plant Growth and Development will be available online in PDF book form soon. The solutions are absolutely Free. Soon you will be able to download the solutions.

Popular Articles