NCERT Solutions for Class 11 Biology Chapter 15 Plant Growth and Development

Plant Growth and Development: Biology NCERT Solutions for Class 11 | Download Free PDF

NCERT Solutions for Class 11 Biology Chapter 15 Plant Growth and Development: According to the CBSE Syllabus 2023-24, Plant Growth and Development NCERT Chapter of Biology Class 11 has been renumbered as Chapter 13. According to CBSE requirements, the Plant Growth and Development Class 11 NCERT Solutions provide explanations and answers to each of the chapter's questions. In order for students to learn and prepare for their exams in a methodical manner, Plant Growth and Development NCERT Solutions PDF 2023 aids in the easy and simple understanding of the topics covered in the chapter. Have you ever thought about where and how structures like leaves, flowers, seeds, fruits, stems, and roots arise, and that too in an orderly sequence? For students' convenience, Careers360 provides NCERT Solutions for Class 11 for other Maths, physics, and chemistry subjects that are simple to access and download. With the sole purpose of helping students prepare for the board exams, NCERT Solutions have been ardently crafted for NCERT Plant Growth and Development.

So in the Plant Growth and Development NCERT PDF, you are going to get questions related to the growth and development of the plant and solutions to these questions. Go through the CBSE NCERT Solutions for Class 11 Biology Chapter 15 - Plant Growth and Development. You must be aware of terms like seedling, plantlet, mature plant and have also seen that trees continue to increase in height or girth over a period of time. Plant Growth and Development Class 11 NCERT Solutions will provide you with detailed answers to every question, such as: Why does the vegetative phase precede flowering in a plant? As per the Class 11 Bio Chapter 15 NCERT Solutions, all plant organs are made up of a variety of tissues; is there any relationship between the structure of a cell, a tissue, or an organ and the function they perform? Find answers to your questions in Plant Growth and Development NCERT Solutions. And, If you are looking for an answer from any other chapter, even from any other class, then go with Class-wise NCERT Solutions, there you will get all the answers.

In Plant Growth and Development NCERT, You will study that growth is one of the most conspicuous events in any living organism. You will learn that growth is an irreversible increase expressed in parameters such as area, length, height, size, volume, cell number, etc. In plants, meristems are the sites of growth. After going through the Plant Growth and Development NCERT PDF, you must be able to understand all the answers to the questions given in this Plant Growth and Development Class 11 NCERT PDF:

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Also, Read

• NCERT Notes for Class 11 Biology Chapter 15 Plant Growth and Development
• NCERT Exemplar for Class 11 Biology Chapter 15 Plant Growth and Development

NCERT Solutions for Class 11 Biology Chapter 15: Plant Growth and Development (Solved Exercise)

The complete solution is given below for Plant Growth and Development NCERT:

Class 11 Chapter 15 Questions and Answers

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

Solution:

Growth:

It is a permanent, irreversible increase in the size of an organ, one of its components, or even a single cell. Metabolic processes that are taking place as a result of the energy support growth.

Differentiation:

A localized qualitative change in the size, biochemistry, structure, and function of cells, tissues, or organs, such as mesophyll, a leaf, a fibre, a vessel, a trachea, or a sieve tube, is known as differentiation. As a result, both the form and the physiological activity change. It leads to specialization in certain functions.

Development:

Development refers to all the changes an organism experiences over the course of its existence.

Dedifferentiation:

Plants that have lost the ability to divide can regain it under specific circumstances. Dedifferentiation is the term used to describe this phenomenon. Example: meristem formation.

Redifferentiation:

It is referred to as redifferentiation when cells produced by dedifferentiation mature to carry out particular functions but once more lose the ability to divide.

Determinate growth:

Determinate growth is the capacity of a cell, tissue, or organism to grow for a specific amount of time. The majority of plants grow indefinitely; however, some plants reach a certain size before ceasing to expand.

Meristem:

The term "meristem" refers to plant tissue made up of undifferentiated cells (meristematic cells).

Growth rate:

A growth rate is an increase in growth per unit of time.

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

Solution:

An increase in protoplasm production leads to growth. The parameters used to measure protoplasmic growth include changes in height, weight, number of cells, fresh tissue sample, length, area, volume, etc. As a result, it is challenging to identify a single growth parameter that characterizes a flowering plant's development over its lifetime.

Plant Growth and Development Class 11 Biology Solutions:

Q 3. Describe briefly.

(a) Arithmetic growth

(b) Geometric growth

(c) Sigmoid growth curve

(d) Absolute and relative growth rates

Solution:

(a) Arithmetic growth

Only one daughter cell divides during arithmetic growth, while the other differentiates and matures. A root extending at a constant rate is the most basic illustration of arithmetic growth.

It can be mathematically expressed as:

Lt = Lo + rt

Lt = length of time ‘t’

Lo = length at the time ‘zero’

R = growth rate/elongation per unit of time

(b) Geometric growth

The initial phase of geometric growth is slow (lag phase), and the subsequent exponential or logarithmic phase sees a rapid increase. Here, both of the progeny cells that result from mitotic cell division are still able to divide. Due to the insufficient nutrient supply, the growth slows down and enters a stationary phase. In geometric growth, the number grows in a multiplicative pattern.

If we plot the growth parameter against time for geometric growth, we obtain a typical sigmoid or S-curve.

Exponential growth can be expressed as:

W1 = Wo ert

W1 = final size

Wo = initial size of the period;

r = growth rate

t = time growth

e = base of natural logarithms

'r' stands for relative growth and the efficiency index, which measures how well plants can produce new plant materials. Wo's initial size determines the final size of W1, thus.

(c) Sigmoid growth curve

Plotting growth against time results in an S-shaped graph that has four main parts: a slow lag phase, exponential phase or rapid phase, stage of diminishing growth, and stationary phase.

(d) Absolute and relative growth rates

The net growth per unit of time is known as the absolute growth rate. The growth rate per unit of time per unit of initial growth is known as the relative growth rate.

Q 4. List five main groups of natural plant growth regulators. Write a note on the discovery, physiological functions and agricultural/horticultural applications of any one of them.

Solution:

Plant growth regulators are the intercellular intrinsic factors (chemical substances) that are responsible for the growth and development of plants.

The following are the top five categories of natural plant growth regulators (PGR):

• Auxins
• Gibberellins
• Cytokinins
• Abscisic acid
• Ethylene

These PGRs are synthesized in various plant parts and regulate various developmental and differentiation processes that occur throughout a plant's life cycle.

Gibberellins

Discovery:

• One of the first gibberellins to be found, designated as GA1, GA2, and GA3, is gibberellic acid, which is acidic.
• More than 100 gibberellins have been identified in a variety of different sources, including fungi and other higher plants.

Physiological functions:

• Plants respond physiologically to gibberellins in a variety of ways.
• They have the ability to increase the length of the axis, which can result in an increase in the length of grape stalks.
• Fruits like apples elongate and acquire a better shape as a result of their presence.
• They are in charge of putting off the senescence process.

Agricultural/horticultural applications:

• The fruits can be left on the tree for longer to increase the market period because the senescence process is delayed.
• Gibberellic acid, or GA3, is a substance that is used to accelerate the malting procedure in the brewing industry.
• By spraying the sugarcane crop with gibberellins, which lengthen the stem and increase yield by up to 20 tonnes per acre because sugarcane stems store carbohydrates as sugar, the crop is able to store more carbohydrates as sugar.
• Spraying GAs on young conifers can shorten their maturation period and promote early seed production.
• Additionally, it encourages the bolting process in plants like cabbage and beets. The elongation of the internode that occurs just before flowering is known as bolting.

Plant Growth and Development Class 11 Biology Chapter 15 Solutions:

Q 5. What do you understand by photoperiodism and vernalisation? Describe their significance.

Solution:

Photoperiodism:

The response of plants to day/night cycles is known as photoperiodism. According to one theory, the hormone that causes flowering is produced in the leaves and then migrates to the shoot apices, where it transforms them into flowering apices. When considering the length of exposure to light, this photoperiodism process aids in the study of how various crop plants respond in terms of flowering.

vernalization:

In some plants, the process of flowering is quantitatively or qualitatively dependent on exposure to lower temperatures. This phenomenon is known as vernalization. It specifically refers to encouraging flowering during a period of lower temperatures. Late in the growing season, the process prevents premature reproductive development, giving the plant enough time to reach maturity.

Q 6. Why is abscisic acid also known as stress hormone?

Solution:

Abscisic acid is responsible for stimulating the closure of stomata in the epidermis and raising the tolerance of plants to different types of stresses. This is why it is also known as the stress hormone. In order to ensure that seeds germinate under favourable conditions, abscisic acid is in charge of promoting seed dormancy. This makes it easier for seeds to withstand desiccation and induces dormancy in plants near the end of the growing season, which encourages the abscission of fruits, leaves, and flowers.

Class 11 Bio Chapter 15 NCERT Solutions:

Q 7. ‘Both growth and differentiation in higher plants are open.’ Comment.

Solution:

Due to the presence of meristems at specific locations of their bodies, higher plants have the ability to retain the capacity to have indefinite growth throughout their life span. Because of these meristems, the cells have the ability to divide and grow on their own. This explains why the growth in higher plants is open. Following several rounds of cell division, some of these cells go through differentiation. Therefore, differentiation is also open.

Q 8. ‘Both a short-day plant and a long-day plant can produce flowers simultaneously in a given place.’ Explain.

Solution:

In a few plants, flowering depends on the relative durations of light and dark periods. Under the condition that they receive enough photoperiod, both long-day and short-day plants can bloom in the same location.

Q 9. Which one of the plant growth regulators would you use if you were 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.

Solution:

The plant growth regulators for the related events are listed below:

(a) induce rooting in a twig. – Auxins

(b) quickly ripen a fruit. – Ethylene

(c) delay leaf senescence. – Cytokinins

(d) induce growth in axillary buds. – Cytokinins

(e) ‘bolt’ a rosette plant. – Gibberellins

(f) induce immediate stomatal closure in leaves. – Abscisic acid

Plant Growth and Development NCERT Solutions PDF 2023 :

Q 10. Would a defoliated plant respond to the photoperiodic cycle? Why?

Solution:

No, a defoliated plant will not respond to the photoperiodic cycle. This is due to the fact that the leaves serve as the sites where dark or light duration is perceived. Therefore, plants would not respond to light if leaves were not present.

Q 11. 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.

Solution:

(a) If GA3 is applied to rice seedlings:

The rice seedlings will show internode-elongation, and hence, an increase in height will be observed.

(b) If dividing cells stop differentiating:

The various plant parts, including the stem and leaves, will not form if the dividing cells stop differentiating.

(c) If rotten fruit gets mixed with unripe fruit:

When unripe fruits are combined with rotten fruits, the unripe fruits ripen more quickly due to the ethylene produced by the rotten fruits, which is a plant growth regulator.

(d) If you forget to add cytokinin to the culture medium:

The processes of cell division, differentiation, and growth will be muted and slow down if cytokinin is not added to the culture medium.

Important Topics of NCERT Solutions for Class 11 Biology Chapter 15 – Plant Growth and Development

The important topics and subtopics given in the Solutions for NCERT Class 11 Biology Chapter 15 Plant Growth and Development are discussed below:

15.1 Growth

15.1.1 Plant Growth Generally is Indeterminate

15.1.2 Growth is Measurable

15.1.3 Phases of Growth

15.1.4 Growth Rates

15.1.5 Conditions for Growth

15.2 Differentiation, Dedifferentiation and Redifferentiation

15.3 Development

15.4 Plant Growth Regulators

15.4.1 Characteristics

15.4.2 The Discovery of Plant Growth Regulators

15.4.3 Physiological Effects of Plant Growth Regulators

15.4.3.1 Auxins

15.4.3.2 Gibberellins

15.4.3.3 Cytokinins

15.4.3.4 Ethylene

15.4.3.5 Abscisic acid

15.5 Photoperiodism

15.6 Vernalisation

NCERT solutions for Class 11 Biology Chapter 15 - Plant Growth and Development

NCERT Solutions for Class 11 Biology Chapter 15 – Plant Growth and Development are covered under Unit 4 – Plant Physiology, included in the latest CBSE Syllabus. According to data compiled from previous years, the Unit on Plant Physiology carries 18 marks. In other words, about 25% of the questions from this unit are included in the exam. If you have any queries in understanding plant growth and development NCERT pdf that are mentioned in this plant growth and development class 11 NCERT pdf then again go through the plant growth and development NCERT, then try to solve them by yourself and compare them with Plant Growth and Development Class 11 NCERT Solutions.

Additionally, Plant Growth and Development Class 11 Biology Solutions, educates students on some of the governing and controlling factors for the various developmental processes. As given in the Class 11 chapter 15 questions and answers, these factors are both internal and external to the plan, or intrinsic and extrinsic. As for Plant Growth and Development NCERT Solutions will help you not only with your school exam but also in the preparation for other competitive exams like NEET.

Highlights of NCERT Solutions for Class 11 Biology Chapter 15 – Plant Growth and Development

The key features of Plant Growth and Development Class 11 Biology Chapter 15 Solutions are listed below:

• Class 11 Biology NCERT Solutions are framed in accordance with the textbook data.
• NCERT Solutions for Class 11 Biology Chapter 15 provide answers to all the questions about NCERT Plant Growth and Development.
• Plant Growth and Development Class 11 Biology Solutions are given in the same order as provided in the textbook.
• Chapter 15 Biology Class 11 NCERT solutions are the ultimate resources for all the academic requirements of students in the CBSE session.
• Solutions of Plant Growth and Development Class 11 NCERT are provided in the most efficient and effective pattern.
• The conceptual knowledge of students can be assessed while referring Class 11 Bio Chapter 15 NCERT Solutions.
• Plant Growth and Development Questions and Answers are easily available in a ready-to-download format.

NCERT Solutions for Class 11 Biology: Chapter-wise

NCERT Solutions for Class 11: Subject-wise

Check the NCERT Books and NCERT Syllabus here:

• NCERT Books Class 11 Biology
• NCERT Syllabus Class 11 Biology
• NCERT Books Class 11
• NCERT Syllabus Class 11