Courses for Kids
Free study material
Free LIVE classes
NEET 2022 | Class 12

NEET Important Chapter - Plant Growth and Development

Get plus subscription and access unlimited live and recorded courses
NEET Notes and Important Questions on Plant Growth and Development

NEET Notes and Important Questions on Plant Growth and Development

Last updated date: 24th Sep 2023
Total views: 347.7k
Views today: 4.48k


This article is created by keeping NEET aspirants in mind. It contains notes and important questions and this article will be great for last-minute revision as well as for clarifying any concept related to the chapter. 

It covers all the important concepts such as the characteristic features of living beings, rules of binomial nomenclature, the difference between taxonomy and systematics, and most importantly these concepts are short and crisp. Along with this, it contains FAQs regarding the NEET exam.

Important Topics of Plant Growth and Development

  • Phases of Growth in Plants

  • Plasticity

  • Plant Growth Regulators

  • Photoperiodism, Vernalisation and Seed Dormancy in Plants

Important Concepts


It is defined as a permanent or irreversible increase in dry weight, size, mass, or volume of a cell, organ, or organism.

Phases of Growth

Plant growth takes place in three phases:

1. Formative Phase

  • It occurs at root apex, shoot apex, and other regions having meristematic tissue.

  • The rate of respiration in the cells of the formative phase is very high.

2. Phase of Enlargement

  • The cells formed during the formative phase that undergo enlargement. 

  • Cell walls of the enlarging cell show plastic extension through enzymatic loosening of microfibrils.

  • A central vacuole forms in the growing cell.

  • Conductive tissues and fibres have the highest elongation.

3. Phase of differentiation or maturation

  • The enlarged cells develop into special types of cells by undergoing structural and physiological differentiation.

  • A cell's shape, size, thickness, and internal structure are all determined by structural differentiation.

  • A cell takes on a specific purpose during physiological differentiation such as absorption through root hairs, metabolite transfer by transfer cells, and so on.

Growth Curve

It is the graphic representation of the total growth against time. When total growth is plotted against time, the result is an S-shaped or sigmoid curve.

It consists of four parts:

  1. Lag phase 

  2. Log phase (exponential phase) 

  3. The phase of diminishing growth 

  4. Stationary phase

Growth is slow in the lag phase, rapid during the log or exponential phase, slow again during the phase of diminishing growth, and growth stops completely during the stationary phase.

Growth Phase Curve

Difference Between Arithmetic Growth and Geometric Growth

Arithmetic Growth

Geometric Growth

Rate of growth is constant.

The rate of growth increases exponentially.

It can be sustained for a long time.

It cannot be sustained for a long time.

It gives a linear curve.

It gives a J-shaped curve.

It is found in stem and root growth.

It is found in the initial multiplication of unicellular organisms and the growth of a very early embryo.

Relative Growth Rate: It is growth per unit initial growth.

It is growth per unit initial growth.

Conditions for Growth 

1. Nutrients: They are raw materials for the synthesis of protoplasm as well as a source of energy. Nutrients should be rich in nitrogenous components for increased synthesis of protoplasm and carbohydrates for energy and cell wall synthesis.

2. Water: It is required for cell elongation, maintenance of turgidity of growing cells, and providing the medium for enzyme action. Even a slight deficiency of water reduces growth. It may, however, promote differentiation. Water stress completely stops growth. 

3. Oxygen: It is essential for aerobic respiration and hence the availability of energy for biosynthetic activity. 

4. Light: It is required for tissue differentiation, synthesis of photosynthetic pigments, and photosynthesis. Its absence results in etiolation. Light also influences certain stages of growth. The phenomenon is called photoperiodism. 

5. Temperature: A temperature of 28-30°C is optimum for proper growth in most plants. Higher temperature above 45°C hinders growth due to excessive transpiration, denaturation of enzymes, and coagulation of protoplasm. Lower temperature inactivates enzymes as well as increases the density of protoplasm. 

6. Gravity: The vector of gravity determines the direction of the shoot and root growth. The direction of light also determines the orientation of leafy shoots. 

7. Other Factors: Excess salt, mineral deficiency, and other stress factors have a detrimental effect on growth.


The sequence of events that occur in the life history of a cell, organ, or organism which includes seed germination, growth, differentiation, maturation, flowering, etc. is called development.

The sequence of events occurring during the development of cells of higher plants

The sequence of events occurring during the development of cells of higher plants


It is a permanent localised qualitative change in the size, biochemistry, structure, and function of cells, tissues, or organs. For example, fibre, vessel, tracheid, sieve tube, mesophyll, leaf, etc.


Regaining the ability to divide after differentiation is called dedifferentiation. For example, dedifferentiation of parenchyma cells to create interfascicular cambium, cork, etc.


Dedifferentiated cells lose their ability to proliferate and mature into specialised functions, such as secondary xylem, phloem, and so on.


Plasticity refers to an organism's or cell's ability to modify its phenotype in response to changes in its surroundings.

Plant Growth Regulators (PGR)

It is a chemical substance other than nutrient produced naturally in plants, which may be translocated to another region, for regulating one or more physiological reactions when present in low concentration. They are broadly divided into two groups: 

1. Plant Growth Promoters

  • They perform activities like cell division, cell enlargement, pattern formation, tropic growth, flowering, fruiting, seed formation, etc.

  • They are three in number, i.e., auxin, cytokinin, and gibberellins.

2. Plant Growth Inhibitors

  • It normally induces dormancy and abscission.

  • It is two in number, i.e., Abscisic acid and Ethylene (it is largely a plant growth inhibitor but is also involved in some growth promotion activities).

Name of Hormone




  • Respiration

  • Metabolism

  • Cell Enlargement

  • Cambial Activity

  • Cell Division

  • Root Formation

  • Apical Dominance

  • Tissue Culture

  • Auxins increase the storage of solutes inside the cell

  • Rooting - Auxins stimulate root formation on the stem cutting. 

  • Parthenocarpy - Auxins are hormones that cause unpollinated pistils to grow into seedless fruits.

  • Flowering - In Litchi and Pineapple, NAA and 2,4-D are frequently used to induce flowering.

  • Pre-Harvest Fruit Drop - In low concentration, 2,4-D is useful in preventing pre-harvest fruit drops of Orange and Apple.

  • Fruits - Auxins enhance the sweetening of fruits.


  • Stem and leaf growth

  • Induce internodal growth

  • Breaks the dormancy

  • Involve in seed germination

  • Promotes sex expression

  • Increases fruit growth.

  • Application of gibberellins to unpollinated flowers produces seedless flowers.

  • It is employed to break dormancy.

  • Delays ripening of fruit.

  • It is used to induce offseason flowering.


  • It is essential for cytokinesis.

  • Involved in cell elongation.

  • Induces the formation of new leaves, chloroplasts in leaves, lateral shoot formation, etc.

  • Delays senescence

  • Increases resistance to high or low temperature and diseases.

  • Used in tissue culture because besides cell division it is also involved in morphogenesis.

  • Increases shelf life of fruits and vegetables.

  • Develops resistance to pathogens and extreme temperature.

  • Delays senescence.


  • Inhibits longitudinal growth but stimulates transverse growth.

  • Induces epinasty.

  • Hastens the senescence of leaves and flowers.

  • Stimulate abscission of various parts (leaves, flowers, fruits).

  • Breaks dormancy.

  • Aids in the ripening of fruits.

  • Used to stimulate colour development and ripening of some fleshy fruits.

  • It has a feminising effect and thus increases the number of female flowers.

  • Helps in the sprouting of storage organs.

  • It shows the thinning effect, i.e., excess flowers and young fruits are thinned by using ethylene to allow better growth of remaining fruits.

Abscisic acid

(stress hormone)

  • Induces dormancy.

  • Stoppage of Cambium activity.

  • Promotes abscission of flowers and fruits.

  • Stimulates senescence of leaves.

  • Prevents transpiration during stress conditions.

  • Induces a positive surface potential on the cell membrane.

  • It is antagonistic to growth-promoting hormones (auxins, cytokinin, gibberellins).

  • It is used as an antitranspirant.

  • Useful in introducing flowering in some short-day plants are kept under unfavourable photoperiods.

  • Promoting rooting in many stem cuttings.

  • It is used to keep buds, storage organs, and seeds in their dormant stage.


The effect of the daily duration of light hours and dark periods on the growth and development of plants mainly flowering plants is called photoperiodism.

On the basis of photoperiodic response to flowering, plants have been divided into the following categories: 

(a) Short Day Plants

They flower when the photoperiod or day length is below a critical period. 

This group includes the majority of winter flowering plants. For example, Xanthium (Cocklebur), Chrysanthemum, Dahlia, Rice, Sug-arcane, Strawberry, Potato, Tobacco, etc.

(b) Long Day Plants 

These plants flower when they receive long photoperiods or light hours which are above a critical length. For example,  Wheat, Oat, Sugar Beet, Spinach, Radish, Barley, etc.

(b) Day Neutral Plants 

The plants can blossom throughout the year. For example, Tomato, Pepper, Cucumber, Cotton, etc.

Three major types of photoperiodic behaviour for flowering

Three major types of photoperiodic behaviour for flowering


It is a process of shortening of the juvenile or vegetative phase and hastening flowering by previous cold treatment.

Site for Vernalization

The stimulus of vernalization is perceived only by the meristematic cells, e.g., shoot tip, embryo tips, root apex, developing leaves, etc.

Requirements of Vernalization

(i) Low Temperature - Low temperature required for vernalization is usually 0°-5°. It is 3°-17° in the case of the biennial Henbane.

(ii) Period of Low Temperature - Treatment. It varies from a few hours to a few days. 

(iii) Actively Dividing Cells - Vernalization does not occur in dry seeds.

Seed Dormancy

It is the innate inhibition of germination of a viable seed even placed in the most favourable environment for germination.

Importance of Seed Dormancy

1. Perennation - Seed dormancy allows seeds to pass through drought, cold, and other unfavourable conditions. 

2. Dispersal - It is essential for the dispersal of seeds. 

3. Germination - Under favourable conditions, seeds germinate only when sufficient water is available to leach out inhibitors and soften the seed coats. 

4. Storage - It is because of dormancy that human beings are able to store grains, pulses, and other edibles for making them available throughout the year and transport them to the areas of deficiency. 

Solved Problems From Chapter

1. What is vernalisation?

Ans: It is a process of shortening of the juvenile or vegetative phase and hastening flowering by a previous cold treatment.

2. What are the three stages of cellular growth?

Ans: The three stages of cellular growth are:

1. Cell division

2. Cell enlargement

3. Cell maturation

Solved Problems of Previous Year Question from the Chapter

1. Name the plant growth regulator that upon spraying on the sugarcane crop increases the length of the stem, thus increasing the yield of the sugarcane crop.

a. Gibberellin

b. Ethylene

c. Abscisic acid

d. Cytokinin

Ans: a. Gibberellin.

When sprayed on sugarcane, gibberellin lengthens the stems, resulting in a 20-tonne-per-acre increase in sugarcane yield.

Trick to Remember: 

Auxin, gibberellin, cytokinin- growth phytohormone

Ethylene, Abscisic acid- growth inhibition phytohormone

2. What is the photoperiod perception site required for the induction of flowering in plants?

a. Leaves

b. Lateral buds

c. Pulvinus

d. Shoot apex

Ans: d. Shoot apex.

The responses of plants to the lengths of dark and light duration are referred to as photoperiodism. 

Leaves are where the photoperiod is perceived. On induction of appropriate photoperiods, such as the hormone florigen, which is responsible for blooming, stimulates flowering by migrating from leaves to shoot apices.

Trick to Remember: Photoperiodism- Cycle of light (day) and darkness (night)

Practice Questions

1. Coconut milk contains a cytokinin called ____ which promotes plant growth.

a. Naphthalene acetic acid

b. Indole-3-acetic acid

c. Gelatin

d. Zeatin

Ans: d. Zeatin.

Cytokinins are a type of plant growth hormone that induces cell division.

Zeatin is a cytokinin-family plant growth hormone. It's a purine ring structure containing hydroxyl, amino, and olefin groups on the side chain.

Structure of Zeatin

2. Seed dormancy is triggered by 

a. Indole-3-ethanol 

b. Abscisic acid 

c. Carbon dioxide 

d. None of the above

Ans: b. Abscisic acid. 

It is a plant hormone that has a role in many aspects of plant growth and development, including seed dormancy and germination.

Key to Remember: Abscisic acid- growth inhibition hormone


This article has been written with NEET aspirants in mind. It covers all of the important ideas and gives concise explanations, making it excellent for effective revision. It includes NEET practice tests and Biology NCERT, as well as essential ideas, concepts, and problems from the previous year's NEET exam questions. Make sure to put your knowledge to the test by doing the Practice question on your own.

See More
NEET Important Dates

NEET Important Dates

View All Dates
NEET 2023 exam date and revised schedule have been announced by the NTA. NEET 2023 will now be conducted on 7-May-2023, and the exam registration closes on last week of Dec 2022. You can check the complete schedule on our site. Furthermore, you can check NEET 2023 dates for application, admit card, exam, answer key, result, counselling, etc along with other relevant information.
See More
View All Dates
NEET Information

NEET Information

Application Form
Eligibility Criteria
Reservation Policy
Admit Card
NTA has announced the NEET 2023 application form release date on the official website NEET 2023 Application Form is available on the official website for online registration. Besides NEET 2023 application form release date, learn about the application process, steps to fill the form, how to submit, exam date sheet etc online. Check our website for more details.
NEET 2023 applicants should be aware of the eligibility criteria before applying to the exam. NTA has released all the relevant information on the official website, i.e. NEET 2023 aspirants should have passed Class 12th or any other equivalent qualifying examination in 2022, 2021, or students appearing in the Class 12th final exam in 2023 can also apply. For further details, visit our website.
As per the union government’s norms, NTA has released the NEET 2023 reservation criteria for different candidates’ categories (SC/ST/OBC/PwD), All India Quota, State Government Quota, Deemed Universities, and more. You can check more details on Vedantu website.
NEET 2023 Admit Card will be released by the NTA in the month of March 2023. Candidates can download the NEET admit card and hall ticket from the NEET official website i.e. For more details on the NEET admit card 2023, candidates can check Vedantu official website.
NEET 2023 Study Material

NEET 2023 Study Material

View NEET Syllabus in Detail
Download full syllabus
Download full syllabus
View NEET Syllabus in Detail
NEET 2023 Study Material

NEET 2023 Study Material

View all study material for NEET
See All
NEET Question Papers

NEET Question Papers

NEET 2023 Book Solutions and PDF Download

NEET 2023 Book Solutions and PDF Download

View all NEET Important Books
NCERT Book for Class 12 Biology
NCERT Book for Class 12 Physics
NCERT Book for Class 12 Chemistry
H. C. Verma Solutions
See All
NEET Mock Tests

NEET Mock Tests

View all mock tests
NEET 2023 free online mock test series for exam preparation are available on the Vedantu website for free download. Practising these mock test papers of Physics, Chemistry and Biology prepared by expert teachers at Vedantu will help you to boost your confidence to face the NEET 2023 examination without any worries. The NEET test series for Physics, Chemistry and Biology that is based on the latest syllabus of NEET and also the Previous Year Question Papers.
See More
NEET 2023 Cut Off

NEET 2023 Cut Off

NEET Cut Off
NTA is responsible for the release of the NEET 2023 cut off score. The qualifying percentile score might remain the same for different categories. According to the latest trends, the expected cut off mark for NEET 2023 is 50% for general category candidates, 45% for physically challenged candidates, and 40% for candidates from reserved categories. For the general category, NEET qualifying marks for 2022 ranged from 715-117 general category, while for OBC/SC/ST categories, they ranged from 116-93 for OBC, 116-93 for SC and 116-93 for ST category.
See More
NEET 2023 Results

NEET 2023 Results

The NEET 2023 result will be published by NTA on in the form of a scorecard. The scorecard will include the roll number, application number, candidate's personal details, and the percentile, marks, and rank of the candidate. Only those candidates who achieve the NEET cut-off will be considered qualified for the exam.
See More
Rank List
NEET 2023 state rank lists will be released by the state counselling committees for admissions to the {state-quota-percentage} state quota and to all seats in private medical and dental colleges. NEET 2023 state rank lists are based on the marks obtained in entrance exams. Candidates can check the NEET 2023 state rank list on the official website or on our site.
The NTA will conduct NEET 2023 counselling at There will be two rounds of counselling for admission under All India Quota (AIQ), deemed and central universities, AIIMS, JIPMER, ESIC, and AFMC. A mop-up round of NEET counselling will be conducted excluding 15% AIQ seats, while the dates of NEET 2023 counselling for 85% state quota seats will be announced by the respective state authorities.
NTA is responsible for the release of the NEET 2023 cut off score. The qualifying percentile score might remain the same for different categories. According to the latest trends, the expected cut off mark for NEET 2023 is 50% for general category candidates, 45% for physically challenged candidates, and 40% for candidates from reserved categories. For the general category, NEET qualifying marks for 2022 ranged from 715-117 general category, while for OBC/SC/ST categories, they ranged from 116-93 for OBC, 116-93 for SC and 116-93 for ST category.
Want to know which Engineering colleges in India accept the NEET 2023 scores for admission to Engineering? Find the list of Engineering colleges accepting NEET scores in India, compiled by Vedantu. There are 1622 Colleges that are accepting NEET. Also find more details on Fees, Ranking, Admission, and Placement.
See More

FAQs on NEET Important Chapter - Plant Growth and Development


1. Do the AIIMS questions come up again in the NEET?

As the question format is more or less the same, you should solve all previous year's papers. If you have time, consider solving the past five years’ JEE MAIN Chemistry and Physics questions, as they are frequently repeated in NEET.

2. What is the number of questions that are asked from Plant Growth and Development in NEET?

The number of questions that come from this chapter is 1.

3. Is it true that the NEET questions are from the previous year?

It is not sure that the fixed number of questions will come from the previous year. Every year, a fresh pattern of questions is created, so only 2 to 3 questions are repeated from the previous year, though this is not guaranteed.