case study on plant growth and development class 11

Class 11 Biology: Case Study of Chapter 15 Plant Growth and Development PDF Download

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In Class 11 Final Exams there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Download of CBSE Class 11 Biology Chapter 15 Case Study and Passage Based Questions with Answers were Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 11 Biology Plant Growth and Development to know their preparation level.

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In CBSE Class 11 Biology Paper, There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

Plant Growth and Development Case Study Questions With Answers

Here, we have provided case-based/passage-based questions for Class 11 Biology  Chapter 15 Plant Growth and Development

Case Study/Passage-Based Questions

Case Study 1:

Plant growth regulators are the chemical substances which govern all the factors of development and growth within plants. Some other names used to refer to it are phytohormones and plant growth hormones. Phytohormones are organic compounds which are either synthesized in laboratories or produced naturally within the plants. They profoundly control and modify the physiological processes like the growth, development, and movement of plants. Based on their actions, plant growth regulators are broadly classified into two major groups: Plant growth promoters

Plant growth inhibitors.

Auxins, Gibberellins, and Cytokinins are grouped into Plant growth promoters while Abscisic acid and Ethylene are grouped into Plant growth inhibitors. Ethylene can be grouped either into the promoters or into the plant inhibitors.

Auxins was first isolated from human urine. The term ‘auxin’ is applied to the indole-3-acetic acid (IAA), and to other natural and synthetic compounds having certain growth regulating properties. They are generally produced by the growing apices of the stems and roots, from where they migrate to the regions of their action. Auxins like IAA and indole butyric acid (IBA) have been isolated from plants. NAA (naphthalene acetic acid) and 2, 4-D (2, 4-dichlorophenoxyacetic) are synthetic auxins. All these auxins have been used extensively in agricultural and horticultural practices. They help to initiate rooting in stem cuttings, an application widely used for plant propagation. Auxins promote flowering e.g. in pineapples. They help to prevent fruit and leaf drop at early stages but promote the abscission of older mature leaves and fruits. In higher plants, the growing apical bud inhibits the growth of the lateral (axillary) buds, a phenomenon called apical dominance. Removal of shoot tips (decapitation) usually results in the growth of lateral buds. It is widely applied in tea plantations, hedge-making. Auxins also induce parthenocarpy, e.g., in tomatoes. They are widely used as herbicides. 2, 4-D, widely used to kill dicotyledonous weeds, does not affect mature monocotyledonous plants. It is used to prepare weed-free lawns by gardeners. Auxin also controls xylem differentiation and helps in cell division.

1.) Identify the incorrect statement about PGR.

• Statement 1 – 2, 4-dichlorophenoxyacetic is natural auxins.
• Statement 2 – Auxin controls xylem differentiation and helps in cell division.
• Statement 3 – Auxins was first isolated from human urine.
• Statement 4 – Indole acetic acid are isolated from plants.

Ans: Statement 1 – 2, 4-dichlorophenoxyacetic is natural auxins.

2.) ___________________ is synthetic auxins

• a) Indole butyric acid
• b) 2, 4-dichloroethynoxyacetic
• c) Naphthalene acetic acid
• d) 4, 2-dichlorophenoxyacetic

Ans: c) Naphthalene acetic acid

3.) Name the plant growth regulator was first isolated from human urine?

Ans: Auxin was the first plant growth regulator isolated from human urine.

4.) Define phytohormones.

Ans: Phytohormones are organic compounds which are either synthesized in laboratories or produced naturally within the plants. They profoundly control and modify the physiological processes like the growth, development, and movement of plants.

5.) Explain apical dominance. Name the hormone that controls it.

Ans: Apical dominance is defined as phenomenon in which the apical bud become dominant and suppresses the growth of lateral buds into branches. Auxin is the plant growth regulator that controls apical dominance.

Hope the information shed above regarding Case Study and Passage Based Questions for Class 11 Biology Chapter 15 Plant Growth and Development with Answers Pdf free download has been useful to an extent. If you have any other queries about CBSE Class 11 Biology Plant Growth and Development Case Study and Passage Based Questions with Answers, feel free to comment below so that we can revert back to us at the earliest possible. By Team Study Rate

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Class 11th Biology - Plant Growth and Development Case Study Questions and Answers 2022 - 2023

By QB365 on 09 Sep, 2022

QB365 provides a detailed and simple solution for every Possible Case Study Questions in Class 11 Biology Subject - Plant Growth and Development, CBSE. It will help Students to get more practice questions, Students can Practice these question papers in addition to score best marks.

QB365 - Question Bank Software

Plant growth and development case study questions with answer key.

11th Standard CBSE

Final Semester - June 2015

Some varieties of wheat are known as spring wheat and some others as winter wheat. The spring wheat is sown and planted in spring and harvested by the end of the same season. The winter varieties if planted in spring fail to flower or produce grain within the same season; they are sown in autumn and harvested around the next mid-summer. (a) What could be the probable reason for this? (b) What term is used for this phenomenon? (c) Name the plant hormone that can replace the above phenomenon.

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Plant growth and development case study questions with answer key answer keys.

(a) A - Shoot apical meristem. B - Vascular cambium. C - Root apical meristem. (b) The arrows indicate the direction of growth of cells and organs. (c) (i) Shoot apical meristem and root apical meristem. (ii) Vascular cambium.

(a) Parallel line technique. (b) A, B, C and D. (c) Characteristics of cells: (i) Increased vacuolation. (ii) Deposition of new cell wall. (iii) Cell enlargement.

A - Arithmetic growth. B - Geometric growth. Differences 

(a) Arithmetic growth (b) A root elongating at a constant rate. (c) It is mathematically expressed as L 1  = L 0  + rt, where L 1  = length at time 't' L 0  = length at time '0' r = growth rate.

(a) A - Lag phase B - Exponential phase C - Stationary phase (b) Geometric growth (c) It is mathematically expressed as W t  = W 0   e rt  where W t  = final size (weight, length etc.) W 0  = Initial size (at the beginning) r = growth rate e = base of natural logarithm t = time of growth.

(a) (i) Absolute growth rate is total growth per unit time. (ii) Relative growth rate is the total growth per unit time per unit parameter. (b) Relative growth rate of A =  \(\frac{10-5}{5} \times 100\)  = 100% Relative growth rate of B =  \(\frac{55-50}{50} \times 100\)  = 10% A shows a higher relative growth rate:.

(a) A - Long day plant. B - Short day plant. C - Day neutral plant. (b) Leaves (c) According to the hypothesis, the hormonal substance produced in the leaves after the necessary inductive photoperiod, migrates to the shoot apices and induces flowering.

(a) The winter wheat requires an exposure to very cold temperature (winter) for phenomenon. (b) It is called vernalisation. (c) Gibberellins can substitute the cold temperature (vernalisation).

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Plant Growth And Development Class 11 Notes PDF (Handwritten & Short Notes)

The Plant Growth And Development Class 11 notes is one of the important study tools while preparing for Class 11 Biology board exam and NEET exam. It is considered to be an important study tool as it explains all the topics and concepts in a broad way. Through this explanation, students can easily build a strong foundation for the chapter Plant Growth And Development. Strong foundation can also be helpful in understanding further chapters in Class 11 Biology. 

The Plant Growth And Development Class 11 notes contains short summaries, key points, definitions, etc. It can help students to improve their grip regarding the chapter Plant Growth And Development. Strong grip regarding the chapter Plant Growth And Development can help students to know their skills and flaws. According to the skills and flaws, students can score well in the questions of the chapter Plant Growth And Development. 

Plant Growth And Development Class 11 Notes PDF

The Selfstudys website provides Plant Growth And Development Class 11 notes in the PDF. Through the Portable Document Format (PDF), Class 11th students can easily access the notes. In the PDF, the topics are arranged according to the latest syllabus. Through this, students can have an updated knowledge for the chapter Plant Growth And Development. 

Students can download the Plant Growth And Development Class 11 notes PDF from their comfort zone if they use our Selfstudys website. With the help of Class 11 Plant Growth And Development Notes, Students can easily solve all their doubts regarding the chapter from their comfort zone. With the help of notes, students can also improve their thinking ability to be able to answer the questions of Plant Growth And Development. 

How to Download the Plant Growth And Development Class 11 Notes?

Students studying in Class 11, should follow some basic tips to download the Plant Growth And Development Class 11 Notes. Steps to download are- 

• Open the Selfstudys website. 
• Bring the arrow towards NCERT Books and Solutions which can be seen in the navigation bar. 
• A pop-up menu will appear, select NCERT Notes from the given list.

• A new page will appear, select Biology from the list of subjects.

• Again a new page will appear, select Plant Growth And Development from the list of chapters. 
• Now one can easily cover the topics and recall the studied concepts of Plant Growth And Development. 

Features of the Plant Growth And Development Class 11 Notes

The Plant Growth And Development Class 11 notes is the most important study tool while covering the chapter as it provides important features. Those important features are:

• Explanations are Given: Explanations to each and every topic and concept are explained in detail. Students can easily understand all kinds 0f topics from easy, moderate, to difficult ones as the topics are elaborated in detail. 
• Available in the PDF Form: These notes are available in the PDF form so that Class 11 Plant Growth And Development notes can be easily accessed. The easy accessibility can help students to score well in the chapter Plant Growth And Development.  
• Colour Diagrams are Given: In the Plant Growth And Development Class 11 Notes PDF, all the diagrams are explained in detail so that students can develop a better understanding of the topics. These diagrams are attractive in nature and it can attract many students to complete the chapter Plant Growth And Development. 
• All Topics are Covered: In the notes of Plant Growth And Development Class 11, all the topics are covered so that students can understand each and every topic in detail. 
• According to the Latest Syllabus: The Notes of Plant Growth And Development Class 11 Biology is arranged according to the latest syllabus. Through this, Class 11th students can build a strong foundation in the topic. 
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• Eye Catching Format: The Class 11 Plant Growth And Development notes maintain an eye-catching format. It is important for Class 11 Biology notes to have noticeable features so that students can easily complete all the topics and concepts.

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After covering the chapter through Plant Growth And Development Class 11 notes, students can be benefited a lot. Those important advantages are -

• Acts as an Important Study Tool: The Class 11 Plant Growth And Development notes as an important study tool as all the important information about the chapter can be obtained easily. 
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• Helps to Focus Throughout the Preparation: The Class 11 Plant Growth And Development notes helps the students to focus while preparing for the Plant Growth And Development chapter. 
• Maintains a Proper Record: Plant Growth And Development Class 11 notes maintains a proper record as it helps students to know everything about the chapter from short brief to long detailed explanation in a systematic manner. 
• Quick Revision: Through the Class 11 Plant Growth And Development notes, students can easily revise all the topics and concepts. With the help of quick revision, students can easily remember the important facts, figures, definitions, etc. 
• For CBSE and State Boards: Students studying in Class 11 CBSE or any of the state boards can use the Plant Growth And Development Class 11 notes. With the help of the notes, students can score well in Plant Growth And Development questions asked in the Class 11th board exam. 

How the Plant Growth And Development Class 11 Notes are Prepared?

The Class 11 Biology notes are generally prepared according to the latest syllabus. Through this, students can have an updated knowledge of all topics and concepts included in the Plant Growth And Development Class 11 notes. By covering all the topics and concepts, students can also score good marks in questions which are related to chapter Plant Growth And Development. Scoring good marks in Class 11 board exams is very important as it helps students to select their desired field. 

Tips for Class 11 Students Preparing for the Plant Growth And Development using revision notes

Class 11 students preparing for the chapter Plant Growth And Development need to follow some basic tips. Those important tips are- 

• Go Through the Topics: Students need to go through all the topics and concepts included in the chapter Plant Growth And Development. Through this, Class 11 students can get a brief idea about all the topics included in the chapter Plant Growth And Development. 
• Cover the Topics: After going through the topics and concepts, students can easily cover the topics included in the chapter Plant Growth And Development. Students can cover all the topics and concepts with the help of Plant Growth And Development Class 11 notes. 
• Practise Questions: After the coverage of all topics, Class 11 students can easily practise questions related to the chapter Plant Growth And Development. 
• Remain Focused: While preparing for Plant Growth And Development, students are advised to remain focused throughout the preparation. It means that students should avoid focusing on other chapters while preparing for the chapter Plant Growth And Development. The Plant Growth And Development Class 11 Notes can be used for this purpose.
• Rectification of Mistakes: It is very important for students to prepare for the chapter with the help of Class 11 Plant Growth And Development notes as it helps to rectify mistakes and doubts then and there. With the help of Plant Growth And Development Class 11 Notes PDF one can also improve their conceptual understanding which will help the students to prevent from making the same mistakes.

Ways Plant Growth And Development Class 11 Notes Can Change One’s Preparation

There are many ways which can change one’s preparation with the help of Plant Growth And Development Class 11 notes. It can help students to cover all the topics included in the chapter as mentioned in the Class 11 Biology Syllabus . By this coverage, Class 11th students can easily identify all kinds of topics: easy, moderate, difficult. Through this, students can score well in the questions related to the chapter Plant Growth And Development. 

What Are Plant Growth And Development Notes Class 11 and Why Should You Care?

The Plant Growth And Development notes Class 11 are mainly a brief about the chapter. In this, all the topics and concepts are explained in a short but precise way. Through this students can cover all the topics and concepts of the chapter Plant Growth And Development that help build a strong foundation for the chapter Plant Growth And Development.

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Plant Growth and Development Class 11 Notes

Plant Growth and Development Class 11 NCERT notes can be easily found on this page. The notes proposed here have been developed by Vidyakul academic experts, primarily based on NCERT textbooks. Notes are provided in order with schematic drawings where applicable. This makes it easier for learners to follow and get the most out of it.

CBSE Class 11 Biology Chapter 15 covers growth stages, growth rates, growth conditions, plant growth regulators, and photoperiod. Students must practice all the in-text questions provided by Vidyakul to achieve the best marks in the exam. Keep reading the article to know NCERT notes for Class Class 11 Biology Chapter 15.

CBSE CLASS 11 BIOLOGY CH-15

Points to remember.

Some of the important points to be remembered from NCERT Class 11 Biology Chapter 15 have been mentioned below:

Growth is one of the most conspicuous events in any living organism.

It is an irreversible increase that can be expressed in terms of size, area, length, height, weight, etc.

It conspicuously involves increased protoplasmic material.

Root and shoot apical meristems, sometimes along with intercalary meristem, contribute to the growth of plants.

 Growth in plants is indeterminate as plants retain the capacity for unlimited growth throughout their life.

When a cell loses the capacity to divide, it leads to differentiation that results in the development of structures that is commensurate with the function the cells finally have to perform.

A differentiated cell may dedifferentiate and then redifferentiate.

Plants exhibit plasticity in development, i.e., the same organ may show different kinds of structures in different phases of life or in different habitats.

Plant growth and development are under the control of both intrinsic and extrinsic factors.

Plant growth regulators (PGRsPGRs) are organic molecules of diverse chemical composition which are synthesized in one part of the plant body and transported to another part where they are active.

Plant growth and development is also affected by light, temperature, nutrition, oxygen status, gravity and such external factors.

The growth hormones are translocated through different tissues, e.g., auxins through parenchyma, GAS and ABA mainly through phloem and cytokinins through the xylem.

Ethylene is a gaseous hormone and is readily absorbed and transported within the plant body.

There are two kinds of flowering stimuli, a hormone called florigen and another is proteinaceous pigment known as phytochrome.

Topics and Sub-topics

Chapter 15, Plant Growth and Development, teaches the students about the basics, such as various phases of growth, different plant growth regulators and other important topics that students will face during their higher grades. Students must explore and find out answers to as many questions as possible to become efficient in the subject.

Below-mentioned is the list of topics present in Class 11 Biology Chapter 15.

Frequently Asked Questions

Winter varieties, when planted in spring, do not produce flowers or mature grains within the span of a flowering season. Explain.

In some plants, flowering is either qualitatively or quantitatively reliant on subjection to lower temperatures, the process is referred to as vernalization. This limits advanced reproductive development rate in maturing season thereby allowing them to have enough time to gain maturity. Vernalisation promotes flowering by a span of low temperatures. Some plants like wheat, barley have two types of varieties – spring and winter varieties. The spring variety is planted in the spring and flowers, producing grains towards the termination of the growing season. While the winter varieties, when planted in spring fail to flower or generate mature grains within the flowering season, this is why they are planted in autumn. Over winter, they germinate and turn out as small seedlings, restarting development in the spring and are gathered in mid-summer.

Several variations of wheat are cultivated in autumn and harvested in the next midsummer.

a) Give reason

b) What is the flowering in lower temperatures referred to as?

c) Name the plant hormone that can substitute for the cold treatment.

a) If planted in spring, winter varieties do not flower or generate mature grains in a span of the flowering season, hence they are cultivated in autumn. Over winter, they sprout and come out as tiny seedlings, resuming growth in the spring and are collected in mid-summer.

b) Vernalisation.

c) Gibberellin.

List a hormone that:

a) Is in nature, gaseous.

b) Is in charge of phototropism.

c) Influences femaleness in cucumber flowers.

d) Is utilized to kill weeds(dicots).

e) In long-day plants, induces flowering.

a) Ethylene(C2H4)

c) Ethylene(C2H4).

e) Gibberellin.

Practice Questions

Write the structural features of

a) Meristematic cells near the root tip

b) The cells in the elongation zone of the root

 Is there a difference in the growth pattern of plants and animals? QDo all parts of the plant grow endlessly? List the regions of the plant that can grow endlessly, if no.

Explain the following with examples from various plant tissues

a) Differentiation

b) De-differentiation

c) Redifferentiation

Why is it difficult to designate any effect to a single hormone during experimentation?

Where are plant hormones formed? How are the hormones passed to the specific site of activity?

What are Plant growth regulators?

Which plant hormone is used to manipulate and stimulate the maturation of sugarcane crop?

 What are the functions of  Auxins in plant growth?

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• CBSE Class 11 Biology Chapter 15 – Plant Growth and Development Class 11 Notes

Plant Growth and Development Class 11 CBSE Revision Notes

While growth remains to be one of the most basic characteristics of all living beings, the one in plants is also essential. In other words, we cannot measure the growth in plants easily but we know it happens. The way plants develop is because of two things that are growth and differentiation. You might wonder how does the structure of plants form. All the plant’s organs are made of a number of tissues. The plant growth and development class 11 notes will make the stages of plant growth clear.

Furthermore, the chapter also explains the various parts of plants like roots, leaves, fruits, and more come into being. It discusses all seed germination and the environment needed for it. Similarly, the chapter will throw light on the plant growth regulators. You know what plants need to grow but there are also things that regulate its growth. This is what plant growth and development class 11 notes will explain to students for a better understanding.

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Sub-topics covered under Plant Growth and Development

• Growth and its Phases – This section will introduce students to the various phases and stages of a plant’s life in terms of growth.
• Plant Growth Regulators – Over here, students will learn about the intrinsic factors which also help in the growth of plants.
• Photoperiodism – You will study why certain plants only occur in certain seasons and why some fruits bear in a specific season.
• Vernalisation – The dependency of plants on the temperatures and how is what students will learn through this part.

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CBSE Class 11 Biology Revision Notes

• CBSE Class 11 Biology Chapter 22 – Chemical Coordination and Integration Class 11 Notes
• CBSE Class 11 Biology Chapter 21 – Neural Control and Coordination Class 11 Notes
• CBSE Class 11 Biology Chapter 20 – Locomotion and Movement Class 11 Notes
• CBSE Class 11 Biology Chapter 19 – Excretory Products and their Elimination Class 11 Notes
• CBSE Class 11 Biology Chapter 18 – Body Fluids and Circulation Class 11 Notes
• CBSE Class 11 Biology Chapter 17 – Breathing and Exchange of Gases Class 11 Notes
• CBSE Class 11 Biology Chapter 16 – Digestion and Absorption Class 11 Notes
• CBSE Class 11 Biology Chapter 6 – Anatomy of Flowering Plants Class 11 Notes
• CBSE Class 11 Biology Chapter 14 – Respiration in Plants Class 11 Notes

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Unit 3: Plant growth and development

Plant growth.

• Arithmetic growth in plants (Opens a modal)
• Geometric growth in plants (Opens a modal)
• Arithmetic and geometric growth - comparison (Opens a modal)
• Plant growth Get 3 of 4 questions to level up!

Plant growth regulators (PGRs)

• Major plant hormones (& how to remember) (Opens a modal)
• Auxin, gibberellin, and cytokinin Get 3 of 4 questions to level up!
• Ethylene and abscisic acid Get 3 of 4 questions to level up!

Plant functions regulated by PGRs

• Photoperiodism (Opens a modal)
• Vernalization (Opens a modal)
• Seed dormancy (Opens a modal)
• Photoperiodism, vernalization, and seed dormancy Get 6 of 8 questions to level up!

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• Plant Growth and Development...
• Plant Growth and Development class 11 Notes Biology

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CBSE Biology Chapter 15 Plant Growth and Development class 11 Notes Biology in PDF are available for free download in myCBSEguide mobile app. The best app for CBSE students now provides Plant Growth and Development class 11 Notes Biology latest chapter wise notes for quick preparation of CBSE board exams and school based annual examinations. Class 11 Biology notes on Chapter 15 Plant Growth and Development class 11 Notes Biology are also available for download in CBSE Guide website.

CBSE Guide Plant Growth and Development class 11 Notes

CBSE guide notes are the comprehensive notes which covers the latest syllabus of CBSE and NCERT. It includes all the topics given in NCERT class 11 Biology text book. Users can download CBSE guide quick revision notes from myCBSEguide mobile app and my CBSE guide website.

Download CBSE class 11th revision notes for Chapter 15 Plant Growth and Development class 11 Notes Biology in PDF format for free. Download revision notes for Plant Growth and Development class 11 Notes Biology and score high in exams. These are the Plant Growth and Development class 11 Notes Biology prepared by team of expert teachers. The revision notes help you revise the whole chapter in minutes. Revising notes in exam days is on of the best tips recommended by teachers during exam days.

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CBSE Quick Revision Notes CBSE Class-11 Biology CHAPTER-15 Plant Growth and Development class 11 Notes Biology

• Root, stem, leaves, flowers, fruits and seeds arise in orderly manner in plants. The sequence of growth is as follows-
• Plants complete their vegetative phase to move into reproductive phase in which flower and fruits are formed for continuation of life cycle of plant.
• Development is the sum of two processes growth and differentiation . Intrinsic and extrinsic factors control the process of growth and development in plants.
• Growth is a permanent or irreversible increase in dry weight, size, mass or volume of cell, organ or organism. It is internal or intrinsic in living beings.
• In plants growth is accomplished by cell division, increase in cell number and cell enlargement. So, growth is a quantitative phenomenon which can be measured in relation to time.
• Plant growth is generally indeterminate due to capacity of unlimited growth throughout the life. Meristem tissues are present at the certain locality of plant body.
• The plant growth in which new cells are always being added to plant body due to meristem is called open form of growth .
• Root apical meristem and shoot apical meristem are responsible for primary growth and elongation of plant body along the axis.
• Intercalary meristem located at nodes produce buds and new branches in plants.
• Secondary growth in plants is the function of lateral meristem that is vascular cambium and cork cambium.

Growth is measurable

• At cellular level, growth is the increase in amount of protoplasm. It is difficult to measure the increase in amount of protoplasm but increase in cell, cell number and cell size can be measured.
• Formative phase is also called as the phase of cell formation or cell division. It occurs at root apex, shoot apex and other region having meristematic tissue. The rate of respiration is very high in the cells undergoing mitosis division in formative phase.
• Phase of Enlargement- newly formed cells produced in formative phase undergo enlargement. Enlarging cells also develops vacuoles that further increase the volume of cell.
• Cell enlargement occurs in all direction with maximum elongation in conducting tissues and fibres.
• Phase of maturation- the enlarged cells develops into special or particular type of cells by undergoing structural and physiological differentiation.
• Growth Rate- increase in growth per unit time is called growth rate. Growth rate may be arithmetic or geometrical.
• Arithmetic Growth- the rate of growth is constant and increase in growth occurs in arithmetic progression- 2,4,6,8 ……. It is found in root and shoot elongation.

L t = L 0 + rt

Length after time = length at beginning + growth rate x time.

• Geometric Growth- here initial growth is slow and increase rapidly thereafter. Every cell divides. The daughter cells grow and divide and the granddaughter cells that result into exponential growth.
• Geometrical growth is common in unicellular organisms when growing in nutrient rich medium.
• Sigmoid growth curve consists of fast dividing exponential phase and stationary phase. It is typical of most living organisms in their natural environment.

Exponential growth can be represented as follows-

W 1  =W 0 e rt . W1 = final size, W0 = initial size, r = growth rate, t = time of growth and e is the base of natural logarithms (2.71828).

• Quantitative comparison between the growth of living system can be made by
• Measurement and comparison of total growth per unit time is called the absolute rate.
• The growth of given system per unit time expressed on a common basis is called relative growth rate.

Condition for growth

• Necessary condition for growth includes water, oxygen and essential elements. Water is required for cell enlargement and maintaining turgidity. Water also provide medium for enzymatic conditions.
• Protoplasm formation requires water and micro and macronutrients and act as source of energy.
• Optimal temperature and other environmental conditions are also essential for growth of the plant.
• Cells produced by apical meristem become specialized to perform specific function. This act of maturation is called differentiation .
• The living differentiated cells that have lost ability of division can regain the capacity of division. This phenomenon is called dedifferentiation . For example interfascicular cambium and cork cambium.
• Dedifferentiated cells mature and lose the capacity of cell division again to perform specific functions. This process is called redifferentiation .

Development

It is the sequence of events that occur in the life history of cell, organ or organism which includes seed germination, growth, differentiation, maturation, flowering, seed formation and senescence.

Sequence of development process in plant cell

• Different structures develop in different phases of growth as well as in response to environment. The ability to change under the influence of internal or external stimuli is called plasticity . Heterophylly in cotton plant is the example of plasticity.

Plant Growth Regulators are simple molecules of diverse chemical composition which may be indole compounds, adenine derivatives or derivatives of carotenoids.

• Auxin was isolated by F.W. Went from tips of coleoptiles of oat seedlings.
• The ‘bakane disease’ of rice seedlings is caused by fungal pathogen Gibberella fujikuroi . E. Kurosawa found that this disease is caused due to presence of Gibberellin.
• Skoog and Miller identified and crystallized the cytokinesis, promoting active substance called kinetin.

Auxin- was first isolated from human urine. It is commonly indole-3-acetic acid (IAA). It is generally produced at stem and root apex and migrate to site of action.

• Cell enlargement.
• Apical dominance
• Cell division
• Inhibition of abscission
• Induce Parthenocarpy
• Cell elongation.
• Breaking of dormancy.
• Early maturity
• Seed germination.

Cytokinins- the plant growth hormone is basic in nature. Most common forms include kinetin, zeatin, etc. They are mainly synthesized in roots.

• Cell division and cell differentiation.
• Essential for tissue culture.
• Overcome apical dominance.
• Promote nutrient mobilisation.

Ethylene – it is a gaseous hormone which stimulates transverse or isodiametric growth but retards the longitudinal one.

Functions –

• Inhibition of longitudinal growth.
• Fruit ripening
• Promote apical dominance

Abscisic Acid – it is also called stress hormone or dormin. It acts as a general plant growth inhibitor. Abscisic acid is produced in the roots of the plant and terminal buds at the top of plant.

• Bud dormancy
• Leaf senescence
• Seed development and maturation.

Photoperiodism- the effect of photoperiods or day duration of light hours on the growth and development of plant, especially flowering is called Photoperiodism. On the basis of photoperiodic response, flowering plants have been divided into the following categories-

• Short Day Plants – they flower when photoperiod is below a critical period (continuous duration of light which must not be exceeded in short day plants and should always be exceeded in long day plants in order to bring them flower). Example- Xanthium, Rice, Sugarcane, Potato etc.
• Long Day Plants – these plants flower when they receive long photoperiod of light, greater than critical period. Example- Radish, Barley, Lettuce.
• Day Neutral Plants – the plant can blossom throughout the year. Example- Bean, Wild Kidney.

Vernalisation – is the process of shortening of the juvenile or vegetative phase and hastening of flowering by cold treatment. The stimulus of Vernalisation is perceived by meristematic cells.

• Vernalisation helps in shortening of vegetative period of plant and brings about early flowering.
• It is applicable to temperate plants like Wheat, Rice, Millets, etc.

Plant Growth and Development class 11 Notes

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• CBSE Revision notes for Class 11 Biology PDF
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CBSE Class-11 Revision Notes and Key Points

Plant Growth and Development class 11 Notes Biology. CBSE quick revision note for class-11 Mathematics, Physics, Chemistry, Biology and other subject are very helpful to revise the whole syllabus during exam days. The revision notes covers all important formulas and concepts given in the chapter. Even if you wish to have an overview of a chapter, quick revision notes are here to do if for you. These notes will certainly save your time during stressful exam days.

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To download Plant Growth and Development class 11 Notes, sample paper for class 11 Chemistry, Physics, Biology, History, Political Science, Economics, Geography, Computer Science, Home Science, Accountancy, Business Studies and Home Science; do check myCBSEguide app or website. myCBSEguide provides sample papers with solution, test papers for chapter-wise practice, NCERT solutions, NCERT Exemplar solutions, quick revision notes for ready reference, CBSE guess papers and CBSE important question papers. Sample Paper all are made available through  the best app for CBSE students  and myCBSEguide website.

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Important Questions Class 11 Biology Chapter 15

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Class 11 Biology Chapter 15 Important Questions – Plant growth and development

Biology is the science of life. It helps us understand various science fields like taxonomy, heredity and evolution. Biologists contribute to conserving the environment by determining ways to protect and conserve our planet for future generations. Educating more people on the importance of preserving various plants and animal species can instil responsibility in every citizen. Chapter 15, Class 11 Biology important questions discuss plant growth and development. 

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Growth is a permanent, irreversible process that increases an organism’s physical and mental capabilities. The three phases of plant growth are meristematic, elongation and maturation. Plant growth and development are crucial for competitive examinations like NEET, MH- CET, and board examinations. Students must practice regularly and solve NCERT exercises and exemplar questions to have  a thorough understanding of  the chapter for an excellent preparation.

Biology is a lengthy subject, with a lot of information to remember. Students often find it challenging to memorise it all together. At Extramarks, we value regular revision through question-solving, which greatly benefits our students studying across different schools in India. 

Our experienced  Biology faculty compiles these Important Questions. These questions have been taken from the NCERT textbook, NCERT Exemplar, past examination questions, and other sources. Our Biology experts  have designed a list of step-by-step answers to help students comprehend each topic along with its  exercises and summary. .

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Access Plant Growth and Development Class 11 Important Questions & Answers for the Academic Year 2022-23.

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Important Questions Class 11 Biology Chapter 15 With Solutions

Our Biology experts have carefully curated Class 11 Biology Chapter 15 important questions which strictly follows NCERT books and provides solved exercises and practice questions to step up their learning experience . The entire list of questionnaires were  prepared by following the latest CBSE guidelines. The chapter elaborates on various topics like intrinsic and extrinsic factors affecting plant growth and differentiation, descriptions of root apical, shoot apical and intercalary meristems, phases of enlargement and maturation, growth rate, arithmetic and geometric growth, plant growth regulators like auxin, gibberellins, cytokinins, ethylene, abscisic acid and others, photoperiodism and vernalisation. Solutions to the Important Questions Class 11 Biology Chapter 15 cover all these essential concepts with explanations.

The list of questions prepared in Important Questions Class 11 Biology Chapter 15 will provide an overview of the chapter and help students summarise the chapter easily. The solutions provided to Important Questions Class 11 Biology Chapter 13 contain explanations for all these essential concepts.

Here is a set of Questions from Important Questions from Class 11 Biology Chapter 15 with their solutions:

Question 1. Winter varieties, when planted in spring, do not produce flowers or mature grains within the span of a flowering season. Explain?

Answer 1: In a few plants, flowering is either qualitatively or quantitatively. Flowering is reliant on its subjection to various internal and environmental factors. Subjection to lower temperatures is referred to as vernalisation. Vernalisation limits the plant’s advanced reproductive development rate. Hence these plants have enough time to gain maturity as it hampers plant growth and development in the maturing season. Vernalisation promotes flowering in plants by a span of low temperatures. Some plants like wheat and barley show two types of varieties, spring and winter. The plants of the spring variety are planted in the spring. The flowers produce grains towards the termination of the growing season. At the same time, the winter varieties planted in spring fail. The winter varieties flower or generate mature grains within their flowering season. Hence they are planted in autumn. Over winter, they germinate and produce tiny seedlings. They restart development in the spring and are gathered in mid-summer.

Question 2. Is there a difference in the growth pattern of plants and animals? Do all parts of the plant grow endlessly? List the regions of the plant that can grow endlessly.

Answer 2: Yes, the growth pattern of plants and animals differs.

Growth in plants happens in indeterminate format. That is plants can grow during their entire life because of the availability of meristematic tissues present in specific parts of the plants i.e. apical intercalary and lateral. These cells of the meristems possess the ability to divide through their lifetime and grow constantly and locally. The rest of the plant body consists of cells eventually losing their capacity to divide. The growth form, in which cells are constantly added to the plant body through the action of meristems, is termed the open form of growth. 

On the other hand the growth in animals happens over a limited period of time after which their body stops growing.

Even in plants all the parts do not grow indefinitely. The shoot apex and root apex having apical meristematic tissues will keep growing and give the vertical elongation of the plants. 

Question 3. What do you understand about photoperiodism and vernalisation? Describe their significance.

Answer 3: A plant’s response to the duration of day and night is known as photoperiodism. Plants primarily respond to the amount of daylight they receive. Based on their response to the duration of light, different plants may be classified as short-day plants, long-day plants, or day-neutral plants. Photoperiodism provides stimuli in addition to flowering induction. The light stimulus in photoperiodism is received only by green leaves. Photoperiodism is mainly mediated by a hypothetical hormone called florigen. Photoperiodism may be nullified by exposing the plant to unfavourable photoperiods. 

Vernalisation is the phenomenon of inducing flowering in plants by exposing them to cold temperatures. In plants of the winter varieties like wheat and some biennials like carrot and cabbage, exposure to cold temperature is necessary to induce flowering. The winter varieties of crops like rye and wheat are usually planted in autumn. They remain in the seedling stage through winter and then flower during the summer. However, if we sow these varieties of crops in spring, flowering will not be seen.

The hormone hypothetically named florigen is believed to be responsible for flowering and is formed in the leaves. Florigen subsequently migrates to the shoot apices and modifies them into flowering apices. 

Vernalisation only prepares the plant to perceive flowering stimuli. It is not observed to induce flowering. Leaves, embryos, and meristems receive the cold treatment stimulus. Vernalisation can be nullified through exposure to high temperatures.

Students should visit the Extramarks website and access Important Questions Class 11 Biology Chapter 15 for further explanation on photoperiodism and vernalisation.

Question 4. Why is abscisic acid called a stress hormone?

Answer 4: Abscisic acid is termed as a stress hormone. It causes different plant responses to act against stress conditions. Abscisic acid helps the plant to survive in unfavourable conditions of the environment. It facilitates the seed dormancy and ensures it gets germinated under favourable circumstances. It also causes the stomata to close when there is a drought. They are also observed to be critical in withstanding desiccation.

Furthermore, they also help the plant by assisting in inducing dormancy in plants towards the termination of the growing season. As a result, they help facilitate the abscission of fruits, leaves and flowers. It is observed that when there is a water deficiency in leaves, i.e. the leaves become dry, ABA concentration increases. Abscisic acid promotes the closure of stomata; hence it is called the stress hormone. 

Question 5. Explain in 2-3 lines each of the following terms with the help of examples taken from different plant tissues? 

(a) Differentiation.

(b) Dedifferentiation 

(c) Re-differentiation

• Differentiation:

When meristematic cells become specialised for performing a particular function, they lose their ability to divide. This phenomenon, called differentiation, is permanent in the size, structure, composition and function of cells, tissue or organs. 

For example, the meristematic tissues in plants give rise to new cells. These cells mature and differentiate into a particular tissue or a different plant organ. For example, cells from root cap distal to root apical meristem, cells of the periphery form epiblema, followed by cortex endodermis, pericycle and vascular dermis. During differentiation, cells undergo significant structural changes in their protoplasm and cell wall.

• De-differentiation:

De-differentiation is the phenomenon in which differentiated living cells regain the capacity of division. The ability of de-differentiation occurs only under particular conditions. In this process, the specialisation of differentiated cells takes place. Hence the cells gain the ability to divide again. For example, in the dicot stem, the cortical cells of the plant get de-differentiated and change into meristematic cells to form cambiums such as interfascicular cambium and fascicular cambium. These meristems are formed from fully developed parenchyma due to the de-differentiation property.

• Re- differentiation:

It is called Re-differentiation when de-differentiated cells mature and gain the specialised function again. The cambium cells that are formed again undergo Re-differentiation to form secondary cortex cells. In the case of secondary growth in woody dicot plants, the secondary cortex cells give rise to secondary xylem, phloem elements, and phelloderm. Cambium forming into the cortex is an example of Re-differentiation.

Question 6. While experimentation, why do you think it is difficult to assign any effect seen to any single hormone?

Answer 6: Plant hormones usually work in a combination. Some plant hormones are observed to have antagonistic effects. At the same time, some others may have augmentative effects. It is nearly impossible to pinpoint any single hormone responsible for a particular effect in a plant part. Phytohormones are synthesised by plant cells individually. These phytohormones are auxin, GA, ABA, ethylene and cytokinin. There is not a separate system for their translocation within plants. So, their effects on plants also remain intermixed.

Many effects of auxin GA show the same function as some other plant hormones. Similarly, ethylene and ABA support each other for various roles in plants. Secondly, the effects of phytohormone in vitro and in vivo will also differ.

Moreover, these plant hormones bring out their effect in coordination with different extrinsic factors. Therefore, it is difficult to assign any effect seen to any single hormone.

Key Topics Covered in Important Questions Class 11 Biology Chapter 15

  Following key points that are covered in Important Questions Class 11 Biology Chapter 15 are as follows:

• Plants complete their vegetative phase to move into a reproductive phase in which flowers and fruits are formed for the continuation of the life cycle of the plant. Development happens due to two processes: growth and differentiation. Intrinsic and extrinsic factors control the growth and development of plants.
• Growth is a permanent or irreversible change. In plants, growth is accomplished by cell division, increasing cell number and enlargement. Root apical meristem and shoot apical meristem are responsible for primary growth. In contrast, plants’ secondary growth is due to lateral meristems like vascular cambium and cork cambium. The three growth phases include the formative phase, phase of enlargement and phase of maturation, in which the plant undergoes structural and physiological differentiation.
• The increase in growth per unit time is called the growth rate. The growth rate can be arithmetic or geometric.
• Comparison and measurement of the total growth per unit time are called the absolute rate. Some parts of plant cells become specialised and undergo differentiation, de-differentiation and  re-differentiation.
• Plant development is the sequence of events in the life history of a cell, organ or organism, including seed germination, growth, differentiation, maturation, flowering, seed formation and senescence. Development is induced through certain plant growth regulators. Some growth-promoting plant regulators include auxin, gibberellin and cytokinins. Ethylene and abscisic acid are termed growth inhibiting regulators.
• The effect of light hours’ duration on plant growth and development is called photoperiodism. Based on this, plants are classified as long days, short days and day-neutral plants. Vernalisation is the process of shortening the vegetative phase by cold temperatures. This stimulus is perceived by meristematic cells.

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Q.1 Bending of shoot tip in absence of light is

Bending of shoot tip in the absence of light is etiolation. It occurs when plants are grown in either partial or complete absence of light, and is characterized by long, weak stems, smaller & sparser leaves due to longer internodes and a pale yellow color.

Q.2 Rita has brought the stem cutting of an exotic variety of rose. In order to make her stem produce roots, she should use

Auxins are growth hormones which promote growth of roots. It is used in horticulture for rooting of stem cuttings.

Q.3 Gibberellins promote

Seed Germination.

Explanation:

Some light sensitive seeds, like Lectuca sativa (Lettuce), germinate in complete darkness with the help of Gibberellins which otherwise require specific light conditions.

Q.4 Mathematically ‘Relative Growth Rate’ can be expressed as 

Relative Growth Rate = (Increase in Volume / Initial Volume) X 100

Mathematically ‘Relative Growth Rate’ can be expressed as: Relative Growth Rate = (Increase in Volume / Initial Volume) X 100.

Q.5 The phase of growth, where synthesis of more protoplasm, formulation of a central vacuole and addition and extension of wall material takes place, is known as

The phase of growth, where synthesis of more of protoplasm, formulation of a central vacuole and addition and extension of wall material takes place, is known as phase of elongation.

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Faqs (frequently asked questions), 1. how do you score good grades in biology.

To get excellent grades in Biology, you must follow your time table with complete discipline and dedication.Most biological concepts require good memory and understanding. Taking notes of important Biology concepts helps solidify the information in your mind. Biology is a complex subject; hence you must encourage yourself to participate actively in the lectures and show involvement. When you struggle to understand a concept or are stuck while solving a question, approach your subject teacher and ask them. Never shy away from asking questions and clarifying your doubts until you get the hang of it. Follow your study schedule religiously. No compromise on that. Be disciplined. These simple techniques will help you score good grades not just in Biology but other subjects as well.

2. What role does Biology play in future career options for students?

The branch of Biology has become one of the most sought-after fields for students to pursue as a career option. A long list of science streams opens doors for students to explore other avenues as well. Jobs offered in the science stream are also highly paid and are in great demand. After completing a degree in the sciences , students can discover various career opportunities in the private and public sector. Hence the scope of Biology is immense than what people perceive it to be.

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NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12

NCERT Solutions For Class 11 Biology Plant Growth and Development

July 30, 2018 by phani

Topics and Subtopics in  NCERT Solutions for Class 11 Biology Chapter 15 Plant Growth and Development :

NCERT Solutions Class 11 Biology Biology Sample Papers

NCERT TEXTBOOK QUESTIONS FROM SOLVED

1.  Define growth, differentiation, development, dedifferentiation, redifferentiation, determinate growth, meristem and growth rate. Solution:  Growth is defined as a vital process which brings about an irreversible and permanent change in the shape, size, form, weight and volume of a cell, organ or whole organism, accompanied with increase in dry matter. Differentiation is a localised qualitative change in size, biochemistry, structure and function of cells, tissues or organs, e.g., fibre, vessel, tracheid, sieve tube, mesophyll, leaf etc. Thus it is a change in form and physiological activity. It results in specialisation for particular functions. Development may be defined as a process which includes growth, differentiation and maturation in a regular sequence in the life history of a cell, organ or organism viz., seed germination, growth, differentiation, flowering, seed formation and senescence. Dedifferentiation is the process by which the differentiated cells which have lost the ability to divide under certain circumstances, become meristematic and regain the divisibility. Redifferentiation is defined as maturation or differentiation of dedifferentiated cells to form cells which are unable to divide e.g., secondary xylem elements, cork cells etc., are formed by redifferentiation of secondary cambial cells. Determinate growth is the ability of a cell, tissue or the organism to grow for a limited period of time. Meristem is a tissue consisting of unspecialised immature cells, possessing the power of continuous cell division and adding new cells to the body. Growth rate is defined as the increased growth per unit time.

2. Why is not any one parameter good enough to demonstrate growth throughout the life of a flowering plant? Solution:  A flowering plant consists of a number of organs viz., roots, stem, leaves, flowers, fruits etc. growing differently under different stages of life cycle. These plant organs require different parameters to demonstrate their growth. In plant organs like fruits, bulbs, corms etc. fresh weight is used for measuring their growth. In case of fruits, increase in volume, diameter etc., are also used as other parameters for the measurement of their growth. For flat organs like leaves, increase in surface area is used as the parameter. Stem and roots primarily grow in length and then in girth, thus increase in length and diameter are used for measuring their growth. Consequently, the flowering plants exhibit several parameters to demonstrate growth.

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4. 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. Solution:  There are five main groups of natural plant growth regulators which are very much recognised as natural hormones in plants. These are:

• Gibberellins
• Abscisic acid

Discovery of auxin: In 1880, Charles Darwin and Francis Darwin worked with the coleoptile of canary grass (Phalaris sp.) and found the existence of a substance in coleoptile tip, which was able to recognise the light stimulus and leads to the bending of tip towards light. Boysen and Jensen (1910-1913) worked on Avena seedling and explained that the substances secreted in the tip are soluble in water (gelatin). Paal (1919) reported that the substances secreted in the tip are translocated downwards and caused cell elongation in half portion which was on the dark side and hence bending was observed in opposite direction. F.W. Went (1928) further refined this experiment and supported the observations of Paal. He was the first person to isolate and name these substances of tip as auxins (Greek Auxein – means ‘to grow’). In 1931, Kogl and Haagen-Smith isolated crystalline compounds from human urine. These were named as auxin-a, auxin-b and heteroauxin.

Physiological functions of auxins:

• Auxins induce cambial cell divisions, shoot cell elongation and early differentiation of xylem and phloem in tissue culture experiments.
• In general, auxins initiate rooting but inhibit the growth of roots. IBA is the most potent root initiator.
• Auxins inhibit the growth of axillary buds (apical dominance) but enhance the size of carpel and hence earlier fruit formation.
• Application of auxins retards the process of senescence (last degradative phase), the abscission of leaves, fruits, branches, etc.
• Auxins induce feminisation, i.e., on male plant, female flowers are produced.

Agricultural/horticultural application of auxins:

• Application of auxins like IAA, IBA, NAA induce rooting in stem cuttings of many plants. This method is widely used to multiply several economically useful plants.
• Normally, auxins inhibit flowering however in litchi and pineapple, application of auxin promotes flowering thus used in orchards.
• Auxin induces parthenocarpy in some plants including tomato, pepper, cucumber and Citrus, thus, produces seedless fruits of more economic value.
• Auxins like 2, 4-D and 2, 4, 5-T are commercially used as weedicides, due to their low cost and greater chemical stability. They are selective herbicides (killing broad-leaved plants, but not grasses).
• For checking premature fruit drop, auxins are applied which prevent the formation of abscission zone in the petiole or just below the fruit. Auxin regulates maturing fruit on the trees of apples, oranges and grape fruit. High doses of auxins can cause fruit drop. Thus, heavy applications of synthetic auxins are used commercially to promote a coordinated abscission of various fruits to facilitate harvesting.
• Auxin, produced in the apical bud, suppresses the development of lateral buds, i.e., apical dominance. Thus practically used in prolonging the dormancy period of potato tubers.
• Naphthalene acetamide is used to prevent the lodging (excessive elongation and development of weak plants, specially in gramineae) or falling of crops.
• Auxin (2,4-D) promotes callus formation in tissue culture. Complete plantlets are regenerated from callus tissue, using auxins and cytokinin which are then transplanted into the soil. Now-a-days, this is a widely practised method of propagation in the field of agriculture and horticulture.

5. What do you understand by photoperiodism and vernalisation? Describe their significance. Solution:  The physiological mechanism for flower-ing is controlled by two factors: photoperiod or light period, i.e., photoperiodism and low temperature, i.e., vernalisation. Photoperiodism is defined as the flowering response of a plant to relative lengths of light/ dark period. Significance of photoperiodism is as follows:

• Photoperiodism determines the season in which a particular plant shall flower. For example, short day plants develop flowers in autumn-spring period (e.g., Dahlia, Xanthium) while long day plants produce flowers in summer (e.g., Amaranthus).
• Knowledge of photoperiodic effect is useful in keeping some plants in vegetative growth (many vegetables) to obtain higher yield of tubers, rhizomes etc. or keep the plant in reproductive stage to yield more flowers and fruits.
• A plant can be made to flower throughout the year by providing favourable photoperiod.
• Helps the plant breeders in effective cross-breeding in plants.
•  Enable a plant to flower in different seasons. Vernalisation is promotion or induction of flowering by exposing a plant to low temperature for some time. Significance of vernalisation is as follows : (i) Crops can be grown earlier. (ii)Plants can be grown in such regions where normally they do not grow. (iii)Yield of the plant is increased. (iv)Resistance to cold and frost is increased. (v) Resistance to fungal diseases is increased.

6. Why is abscisic acid also known as stress hormone? Solution:  A fairly high concentration of abscisic acid (ABA) is found in leaves of plants growing under stress conditions, such as drought, flooding, injury, mineral deficiency etc. It is accompanied by loss of turgor and closure of stomata. When such plants are transferred to normal conditions, they regain normal turgor and ABA concentration decreases. Since the synthesis of ABA is accelerated under stress condition and the same is destroyed or inactivated when stress is relieved, it is also known as stress hormone.

7. ‘Both growth and differentiation in higher plants are open’. Comment. Solution:  Plant growth is generally indeterminate. Higher plants possess specific areas called meristems which take part in the formation of new cells. The body of plants is built on a modular fashion where structure is never complete because the tips (with apical meristem) “are open ended – always growing and forming new organs to replace the older or senescent ones. Growth is invariably associated with differentiation. The exact trigger for differentiation is also not known. Not only the growth of plants are open- ended, their differentiation is also open. The same apical meristem cells give rise to different types of cells at maturity, e.g., xylem, phloem, parenchyma, sclerenchyma fibres, collenchyma, etc. Thus, both the processes are indeterminate, unlimited and develop into different structures at maturity i.e., both are open.

8. ‘Both a short day plant and a long day plant can produce flower simultaneously in a given place’. Explain. Solution:  A short day plant (SDP) flowers only when it receives a long dark period and short photoperiod, e.g., Xanthium, Dahlia etc. On the other hand, a long day plant (LDP) will flower only when it receives a long photoperiod and short dark period, e.g., wheat, oat etc. Thus critical photoperiod is that continuous duration of light which must not be exceeded in SDP and should always be exceeded in LDP in order to bring them to flower. Xanthium requires light for less than 15.6 hrs and Henbane requires light for more than 11 hrs. Xanthium (a SDP) and Henbane (DP) will flower simultaneously in light period between 11 to 15.6 hrs.

9. 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. Solution:  (a) Auxins like IBA, NAA. (b) Ethylene (c) Cytokinins (d) Cytokinins (e) Gibberellins (f) Abscisic acid (ABA)

10. Would a defoliated plant respond to photo- periodic cycle? Why? Solution:  No, a defoliated plant would not respond to photoperiodic cycle because photoperiodic stimulus is picked up by the leaves only. Even one leaf or a part of it is sufficient for this purpose. For perception of photoperiodic cycle, there must be the presence of leaves under inductive photoperiod, so that, the hormone responsible for flowering can be produced.

11. What would be expected to happen if: (a)  GA 3 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) The coleoptile will elongate rapidly, as GA 3 helps in cell growth. (b) The development of callus (mass of undifferentiated cells) will take place. (c) The unripe fruits will ripe quickly because of the increased rate of respiration due to emission of ethylene from rotten fruit. (d) Cell division will retard and shoot will not initiate from the callus.

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Important Questions Class 11 Biology Chapter 15 Plant Growth and Development for CBSE

Important questions for class 11 biology 15th chapter plant growth and development mcq, very short, short type, long type.

CBSE Class 11 Important Questions for Class 11 Biology Chapter 15 Plant Growth and Development all MCQ Type, Very Short Type, Assertion Reason Type, Case Study, Short Type and Long Type Questions with Answers by Expert. Important Questions for Section A, B, C, D Class 11 Biology Chapter 15.

b.) geometric growth

d.) relative growth

c.) Francis Darwin

d.) Abscisic acid

Q.5) Assertion: Auxin is used as herbicide

Reason: Auxin is used to kill monocotyledonousweeds, does not affect mature dicotyledonous plants.

d.) if both assertion and reason are false.

a.) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

d.) bolting

Q.8) Which growth hormone promotes bolting? (a) Auxins (b) Gibberellins (c) Ethylene (d) Cytokinin

Q.3) What are the three phases of growth?

Q.5) State the functions of Kinetin.

3.)  Plasticity can be seen in the phenomena of heterophylly.

3.) Ethylene is an excellent ripening agent.

2.) Turgidity of cells aids in cell growth extension. As a result, plant growth and development are inextricably tied to the plant’s water state.

2.) The presence of meristems at specific sites throughout the plant’s body gives it this power.

Q.2) What are the methods to break food dormancy?

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Important Questions for Class 11 Biology Chapter 15 - Plant Growth and Development

• Class 11 Important Question
• Chapter 15: Plant Growth And Development

Download CBSE Class 11 Biology Chapter 15 Important Questions

CBSE Class 11 Biology Chapter 15 Plant Growth and Development Important Questions are available here in the downloadable PDF format for students to boost their exam preparation. These important questions are created by subject experts and are exclusively designed after comprehensive research. Students may find few of these questions during the actual Biology exam. So, they are advised to practice well.  These important questions also contain some questions which have been repeatedly examined in Class 11 previous year examinations . If a student doubts any topic of the chapter, they can clear it by practising these important questions. These questions also help the students to prepare competently for competitive exams like NEET . Click on the pdf link below to download the Important Questions for CBSE Class 11 Biology Chapter 15 free PDF.

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Also, check CBSE Class 11 Biology Important Questions for other chapters:

Topics Covered in Class 11 Biology Chapter 15

Differentiation, Dedifferentiation, Redifferentiation

Development

Plant Growth Regulators

Photoperiodism

Vernalisation

Study Important Questions for Class 11 Biology Chapter 15 – Plant Growth and Development

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

Growth is a permanent and irreversible rise in the size of an organ, its parts, or even a single cell.

Differentiation is the process by which cells from the root apical and shoot apical meristems, as well as the cambium, develop and execute specialized tasks.

The term "development" refers to all the changes that an organism goes through during its life cycle, from seed germination to senescence.

Under some conditions, permanent plant cells regain the ability to divide, a process known as dedifferentiation.

Redifferentiation refers to the process through which dedifferentiated cells mature and lose their ability to divide.

Determinate growth refers to growth that comes to a halt after a given stage

In plants, meristems are specialized areas where active cell division occurs.

Growth rate refers to the amount of growth per unit of time.

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

Ans: At the cellular level, growth is mostly due to a rise in the amount of protoplasm. The weight of the fresh tissue sample, the weight of the dry tissue sample, the variations in length, area, volume, and cell number determined over the growth phase are all used to measure protoplasm growth. As a result, no one metric can adequately represent growth across the life of a blooming plant.

3. Describe briefly: 

Arithmetic growth

Geometric growth 

Sigmoid growth curve 

Absolute and relative growth rates

In arithmetic growth, only one daughter cell divides after mitotic cell division, while the other differentiates and develops. Arithmetic growth is defined as the elongation of roots at a constant pace. A linear curve is generated by charting the organ's length versus time. It can be stated mathematically as:

$\mathrm{L}_{\mathrm{t}}=\mathrm{L}_{0}+\mathrm{r}$

As a result, $L_{\text {t }}$ denotes length at time ' $\mathrm{t}$, ' $\mathrm{L}_{0}$ denotes length at time 0 , and $\mathrm{r}$ denotes the rate per unit of time.

In most systems, the first growth is modest and is referred to as the lag phase, after which it accelerates at an exponential rate and is referred to as the log or exponential phase. Following mitotic cell division, both child cells retain the ability to divide and continue to do so. However, when nutrition availability is limited, growth slows and eventually stops, resulting in a stationary phase. A sigmoid curve emerges from the graph of geometric growth.

In a natural setting, a sigmoid curve is a feature of living organisms. The lag phase, the log phase or exponential phase of rapid expansion, and the stationary phase are the three phases of this curve.

Graph of Exponential Growth

The following is an example of exponential growth:

$\mathrm{W}_{1}=\mathrm{W}_{0} \mathrm{e}^{\pi}$

$\mathrm{W}_{1}=$ final dimensions (weight, height, number etc.)

$\mathrm{W}_{0}=$ the starting size at the start of the period

$\mathrm{r}=$ the rate of growth

$\mathrm{t}=$ growth period

e $=$ natural logarithms' base

The absolute growth rate is the measurement and comparison of total growth per unit time.

The relative growth rate is the growth of a system per unit time represented on a common foundation, such as per unit beginning parameter.

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.

Ans. Natural plant growth regulators are divided into five categories:

(i) Auxins 

(ii) Gibberellic acid

(iii) Cytokinins 

(iv) Ethylene 

(v) Abscisic acid

Auxins have been discovered, have physiological activities, and are used in agriculture and horticulture.

Discovery: Charles Darwin and Francis Darwin made the first observations about auxin effects when they noticed that the coleoptiles of canary grass responded to unilateral illumination by growing towards the light source (phototropism). Following a series of trials, it was determined that the coleoptile's tip was the source of the transmittable effect that caused the entire coleoptile to bend. F.W. Went isolated auxin from the tips of coleoptiles of oat seedlings.

Physiological Functions:

They regulate the proliferation of plant cells.

They are responsible for the apical dominance phenomena.

They regulate vascular cambium division and xylem differentiation.

They cause parthenocarpy and prevent leaf and fruit abscission.

Horticulture Application:

They aid in the establishment of roots in stem cuttings, a popular method of plant multiplication.

Weedicide 2-4 D is used to kill broadleaf, dicotyledonous weeds.

They cause tomatoes to go into parthenogenesis.

It promotes flowering in plants, such as pineapples.

5. What do you understand about photoperiodism and vernalization? Describe their significance.

Ans. Photoperiodism refers to a plant's response to day/night cycles. The hormonal substance responsible for flowering is thought to be produced in the leaves before traveling to the shoot apices and transforming them into flowering apices. Photoperiodism aids in the study of flowering in diverse crop plants in relation to the time of light exposure.

There are certain plants whose flowering is quantitatively or qualitatively influenced by low temperatures. Vernalization is the word for this phenomenon. It specifically refers to a time of low temperature that promotes blossoming. It delays precocious reproductive development in the late stages of the growing season, giving the plant enough time to mature.

6. Why is Abscisic acid also known as a stress hormone?

Ans. Abscisic acid promotes plant tolerance to diverse stressors by stimulating the closing of stomata in the epidermis. As a result, it's also known as the stress hormone. It encourages seed dormancy and assures seed germination when conditions are favorable. It aids desiccation resistance in seeds. It also aids in the induction of dormancy in plants at the conclusion of the growing season and promotes leaf, fruit, and flower abscission.

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

Ans. The higher plants can develop indefinitely throughout their lives. The presence of meristems at specific sites throughout the plant's body gives it this power. These meristems' cells can divide and self-perpetuate. As a result, increased plant growth is possible. In addition, after a few rounds of cell division, some of these cells inevitably undergo differentiation. As a result, the distinction is also open.

8. ‘Both a short day plant and a long day plant can flower simultaneously in a given place’. Explain

Ans. Some plants' flowering is influenced by the lengths of light and dark phases. If both the short-day and long-day plants are given an adequate photoperiod, they can flower at the same time.

9. Which one of the plant growth regulators would you use if you are asked to: 

Induce rooting in a twig 

Quickly ripen a fruit 

Delay leaf senescence 

Induce growth in axillary buds 

‘Bolt’ a rosette plant 4 

Induce immediate stomatal closure in leaves.

Ethylene 

Cytokinins 

Gibberellins 

Abscisic acid

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

Ans. No, because the leaves are the locations of sensing of light/dark duration, a defoliated plant will not respond to the photoperiodic cycle. As a result, the plant would not respond to light if it lacked leaves.

11. What would be expected to happen if: 

$GA_{3}$ is applied to rice seedlings 

Dividing cells stop differentiating 

A rotten fruit gets mixed with unripe fruits

You forget to add cytokinin to the culture medium.

Ans.  

When $GA_{3}$ is administered to rice seedlings, the internode lengthens, and the height of the rice seedlings increases.

Plant organs such as leaves, and stems will not form if dividing cells stop differentiating.

If decaying fruits are mixed with unripe fruits, the ethylene released by the rotten fruits will speed the unripe fruits' ripening.

Cell division, growth, and differentiation will be slowed if cytokinin is not added to the culture media.

Benefits of Solving CBSE Class 11 Biology Chapter 15 Plant Growth and Development Important Questions 

Solving Class 11 Biology Chapter 15 questions can be useful for students. Find some of the benefits of practising these questions below.

Students will get an idea of different questions that can be asked during the exam and their difficulty levels.

These will help develop time management skills as students learn how much time it takes to solve a question.

They cover all the important concepts of the chapter in a short time.

The questions will be of great help during revision.

Students will easily understand the difficulty level of the questions during the exam.

Extra Questions for Practice

Very short answer type questions.

Why is plant growth unique?

Define growth.

What are the different parameters used to measure growth?

Define growth rate.

Name the three phases of Growth.

Short Answer Type Questions

Where did the term “Auxin” apply?

Explain Gibberellins.

Explain the term  “Long Day Plants, Short Day Plants, and Day-Neutral Plants.

What is vernalisation?

Explain the term “Plasticity”.

Long Answer Type Questions

What are the different characteristics of plants' growth regulators?

What are the necessary conditions for the growth of the plant?

Explain the different phases of growth in detail.

We hope students have found this information on CBSE Important Questions for Class 11 Biology Chapter 15 useful for their studies. Along with important questions, students can also access CBSE Class 11 Biology revision notes , NCERT Solutions , useful tips, and more on the official website of Vedantu. Keep learning and stay tuned with us for further updates on CBSE and other competitive exams. 

FAQs on Important Questions for Class 11 Biology Chapter 15 - Plant Growth and Development

1. Why should I refer to Vedantu’s important questions for Class 11 Biology Chapter 15?

Solving important questions is one of the best ways to self-evaluate your knowledge of the chapter. Referring to important questions for Class 11 Biology Chapter 15 pdf provided by Vedantu helps your problem-solving and time management skills as all the important concepts are explained in an easy language to help students better understand the chapter. Regular practice allows students to answer knowledge-based questions easily and accurately in the exams.

2. What is the weightage of  Class 11 Biology Chapter 15?

According to the research made by the experts considering the previous year's question paper, you can expect approximately 18 marks, or 25% of the question paper can have questions from this unit. To grasp the important concepts of this chapter,  it is highly recommended to download the pdf and refer to them to get a stronghold on the important topics and know how to write answers in the exam as per the marking scheme.

3. How is plant growth measured?

The growth of a few plants is measured by different parameters, including an increase in cell number, cell size, fresh weight, dry weight, length, area, and volume, while the growth of a pollen tube is measured in terms of its length, increase in surface area, and so on.

4. How is the growth period classified in Class 11 Biology Chapter 15?

The period of growth is divided into three phases: meristematic, elongation, and maturation.

5. What are ‘Plant hormones’?

Plant hormones are organic substances that regulate plant growth and development. Plant hormones are also known as phytohormones.

CBSE Class 11 Biology Important Questions

Cbse study materials.

• CBSE Notes For Class 11
• CBSE Class 11 Biology Notes
• Chapter 15: Plant Growth And Development

Plant Growth and Development Class 11 Notes - Chapter 15

According to the CBSE Syllabus 2023-24, this chapter has been renumbered as Chapter 13.

Like animals, even plants undergo growth and development. But unlike animals which have a definite lifespan, most plants can grow indefinitely. But how exactly is growth defined?

Plant Growth and Development

Growth is defined as an irreversible change in physical form. In plants, a combination of cell growth and cell division results in an almost indefinite growth. This ability is due to the presence of tissues called meristems at certain parts of the plant body.

See Also:   Important Questions for Class 11 Biology- Plant Growth and Development

Growth – Plant Growth Generally is Indeterminate

• Plants are known to retain the capacity to grow indefinitely throughout their life, hence their growth is unique. This capability can be contributed to the presence of meristems(possessing the capacity to self-perpetuate and divide) at different locations in their body.
• The root and shoot apical meristems are responsible for the primary growth of the plants contributing to the plant elongation through the axis.
• The lateral meristems, vascular cambium, and cork-cambium in gymnosperms and dicotyledonous plants appear later. These meristems increase the girth of active structures resulting in the secondary growth of plants.

Growth – Growth Is Measurable

• At the cellular level, it is the increase in the amount of protoplasm. Growth is measured by a variety of metrics, such as an increase in dry weight, fresh weight, area, volume, length, and cell number.
• In some plants, growth is expressed as an increase in the cell number and increase in cell size, while in some others, growth is measured in terms of the growth of pollen tube, lengthwise, increase in surface area and so on.

Growth – Phases Of Growth

The growth period can be classified into three phases – meristematic(root and shoot apex cells that are constantly dividing), elongation (proximal cells to the meristematic region)and maturation(proximal cells to the elongation phase cells)

Growth Rate

The growth rate is referred to as the increased growth per unit of time. Entities can produce cells in many ways – arithmetic and geometric. Quantitative similarities or differences between the growth of living entities can be done in two ways – absolute growth(measurement and comparison of total growth per unit time) and relative growth rate(growth of given system per unit time)

Differentiation, Dedifferentiation And Redifferentiation

Differentiation –  cells from the root, shoot apical meristems and cambium differentiate and mature to carry out different functions. Here the cells undergo some major structural changes both in cell walls and protoplasm.

Dedifferentiation- differentiated cells, after losing the capability to divide, regain the capacity of division in some circumstances. Example – cork cambium forming fully differentiated parenchyma cells.

Redifferentiation – During dedifferentiation, meristems and tissues divide and produce cells again, losing the capacity to divide, however, mature to carry out specific functions. For example -woody tissues in dicotyledonous plants undergo redifferentiation.

Plant Growth Regulators

Plant growth regulators are essentially hormones that control various functions related to the growth and development of the plant. They can be of two types, namely:

• abscisic acid
• Benzoic acid
• Salicylic acid
• Gibberellins

In-depth reading:   Plant Growth Regulators

Growth Inhibitors, as the name suggests, inhibit the growth of plants and induce dormancy. Growth Promoters promote flowering, the formation of seeds, cell division etc.

For more information on Plant Growth Regulators, watch the below video

Photoperiodism

The response of plants to durations of day/night is known as photoperiodism, as flowering in some plants is based on the combination of light and dark exposures and relative durations. Here, the site of perception of light and dark durations are leaves.

Vernalisation

Depending on exposure to lower temperatures of flowering plants, either qualitatively or quantitatively, is known as vernalisation. This process checks precocious reproductive development sometime later in the growing season. Especially it can be referred to as the promotion of flowering by a duration of low temperature.

To explore important questions or related concepts about Plant Growth and Development Class 11, register at BYJU’s.

Further Reading:-

Frequently Asked Questions on CBSE Class 11 Biology Notes Chapter 15 Plant Growth and Development

What is meant by growth rate.

Plant growth rate can be measured as the relative increase in leaf area over time by substituting total plant leaf area for total biomass in the conventional RGR equation.

What are auxins?

Auxins are a growth factor hormone which is naturally produced by the plant itself.

What is the difference between growth promoters and growth inhibitors?

Growth promoters promote flowering, the formation of seeds, cell division etc. Whereas growth inhibitors, as the name suggests, inhibit the growth of plants and induce dormancy.

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MCQ Questions for Class 11 Biology: Ch 15 Plant - Growth & Development

Mcq questions for class 11 biology: ch 15 plant - growth & development.

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