Plant Growth and Development: Topics, Overview, Phases, Factors, Books, Tips, Questions

Edited By Irshad Anwar | Updated on Oct 24, 2024 05:23 PM IST

Growth is the permanent, irreversible growth within the length of an organism. This function is determined in all organisms, observed with the aid of using numerous metabolic strategies. In plants, the process begins when the seeds germinate and change into a brand-new seedling, which eventually develops into a new plant. Plant Growth and Development is an important topic in biology, as it explains how plants respond to their environment, adapt to changes, and regulate growth through hormones. Explore more about Chapter overview, important topics, plant growth definition and meaning, process, phases of growth, factor affecting, growth regulators, books and tips.

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Important Topics of Chapter Plant Growth and Development
Overview of the Chapter Plant Growth and Development
What is Plant Growth?
Processes in Plant Growth
Plant Growth and Development: Phases of Growth
Factors Affecting Plant Growth
Differentiation
Plant Growth and Development Regulators
Tips, Tricks, and Strategies to Prepare for Plant Growth and Development
Types of Questions Asked on Plant Growth and Development
Prescribed Books for Plant Growth and Development
Recommended Video on Plant Growth and Development

Plant Growth and Development: Topics, Overview, Phases, Factors, Books, Tips, Questions

Important Topics of Chapter Plant Growth and Development

Process of Plant Growth
Phases of Growth and Development
Plant Growth and Development Regulators
Important Concepts - Cell differentiation, Auxin, Gibberellins, Cytokinin

Overview of the Chapter Plant Growth and Development

This chapter Plant Growth and Development specifies how plants grow and develop, with different growth stages and also the influence of water, light, and minerals. The chapter focuses on plant hormones like auxins, gibberellins, cytokinins, ethylene, and abscisic acid, which control growth processes like germination and flowering. Concepts like photoperiodism and vernalization are introduced. This chapter helps us understand how plants grow and adapt to their surroundings.

What is Plant Growth?

Growth can be defined as a permanent increase in the size and mass of a plant and involves cellular enlargement and cell division. Development would then be the series of events that happen in the life history of a plant from germination through flowering, fruiting, and senescence. In this context, development will be key to the mere existence of a plant and reproductive success since it allows plants to produce seeds for the next generation.

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Various factors influence the growth and development of plants, among which are genetic makeup, environmental conditions, and hormonal regulation. Other factors controllable or uncontrollable to man are the genetic make-up, the environmental conditions such as light, temperature, water, and nutrients, and hormonal regulation. Knowing and understanding all these would be of much help in maximising these agricultural practices for the sake of healthy plant development.

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Plant Growth and Development Basics

Plants can generally grow indefinitely due to the presence of tissues like meristems which help in both the primary as well as secondary growth of the plant. Growth can be measured in different metrics such as weight size and cell count. Some of the important measurements are discussed below:

Primary Growth: There is growth seen in the root and shoot of the apical meristems along the plant axis.
Secondary Growth: Lateral Meristems increase their growth in gymnosperms and dicotyledons.
Measurable Growth: This is generally seen in protoplasm, dry/fresh weight, volume or cell number growth.

Processes in Plant Growth

Cell division is the basis of growth in plants.

Cell Division

Mitosis results in a process in which one cell divides and gives rise to two identical daughter cells that are mirror images of each other, and the mother cell—process is used to help in growth, repairing, and asexual or amoebic reproduction in plants. Conversely, meiosis takes place in the reproductive organs of the organism and varieties of gametes, that is, the sperm and egg, to quickly enhance the ability of the species to carry on with the sexual means of reproduction.

Prophase: The chromosomes begin to condense and may now be visible.
Metaphase: The chromosomes orient themselves at the cell's equatorial plate.
Anaphase: Sister chromatids separate, moving toward opposite poles.
Telophase: Nuclear membranes re-establish around each set of chromosomes.
Cytokinesis: The cleavage of the cell into two separate daughter cells.

Cell Enlargement

The cells take up water, increase in volume, and tend to force the cell walls from outside during cell turgor pressure. This is due to the water intake in the central vacuole, which causes the swelling of the cell.

Role of Turgor Pressure

Turgor pressure is the pressure exerted on the cell wall by the cell membrane; when this is absent, the cells are flaccid. It is therefore responsible for the stiffness of cells, hence cell enlargement. It is the result of the osmotic flow of water into a cell and it provides the force for cell growth, leading to the extension of plant tissues.

Cell Differentiation

Cell differentiation is simply a process in which the cells are cast into different classes of cells, each having distinct functions. That, in turn, would make the process of cell differentiation extremely indispensable for the development of tissues and organs which helps a plant carry on several of these kinds of complex activities like nutrient absorption, photosynthesis, and reproduction later on.

Example: Differentiation in Root and Shoot Systems

In the root system, cells differentiate into root hair cells, thus expanding the surface area for the absorption of water and nutrients. In the shoot system, cells differentiate into a variety of cell types, including xylem and phloem cells that function in water and nutrient transport and photosynthetic cells in leaves.

NCERT Books Link:

Plant Growth and Development: Phases of Growth

There are various stages of Plant Growth.

Germination

Imbibition: The seed imbibes water, swells, and the seed coat cracks.
Activation: Metabolic processes go active, enzymes are activated, and stored food reserves are mobilized.
Emergence of Radicle: First, the root appears and anchors the seedling. The radicle then begins to take water and nutrients.
Emergence of Plumule: The shoot is next to appear, growing directionally toward the light

Factors Affecting Germination

Water: Important for the process of imbibition and the activation of enzymes.
Oxygen: this is required to provide energy for growth by respiration.
Temperature: It requires an optimum temperature for enzyme activity.
Light: Many seeds germinate in response to light, others in darkness.

Vegetative Growth

Vegetative growth can be described as the stage at which the plant's development becomes more considerable and more covering of root, stem, and leaf growth. This undertaking is at a sensitive period when the tough frame that eventually will support reproductive growth is put in place.

Role of Meristems

Apical Meristems: found in the root and shoot apices; they account for primary growth; for elongation.
Lateral Meristems: the vascular and cork cambium; account for secondary growth; for thickening.
Intercalary Meristems: Found in the base of leaf blades or internodes; the cause for grass to sprout

Reproductive Growth

The phases in reproductive growth in plants include:

Vegetative to the Reproductive Phase

The process is accompanied by alteration of gene expression and hormonal regulation and concludes with flowers, fruits, and seeds. The transition is often environmental, induced by stimuli such as light, temperature, and photoperiod, among others.

Flowering and Fruiting

Flowering: the formation of flowers; these are essentially the sexual organs of the plant.

Fruiting: fruits, in post-fertilization, are structures that primarily protect the seeds but aid in their dispersal as well.

Some major points are discussed below in the table:

Phases of Growth	Explanation
Formative Phase	At the initial phase of plant growth, there is cell division (mitosis) which involves two different stages: Karyokinesis ( division of the nucleus) Cytokinesis ( division of cytoplasm)
Cell Enlargement and Differentiation	There is an increasing size of cells and in the process, there is the formation of protoplasm, absorption of water and form of vacuoles. There is also thickening of the cell wall and permanent cell walls are formed.
Cell Maturation	Definite shape and structure of the cell is formed which facilitates the differentiation of individual cells and tissues.
Leaf Development	Regulated dynamic process which involves differentiation of leaf components and their size and shape.
Root Development	Embryogenesis takes place and there is the formation of pro meristem. There is proper germination of cell division in the meristem that expands the roots axially.

Factors Affecting Plant Growth

The environmental factors affecting plant growth and development are:

Light

Light is one of the factors in photosynthesis, which is the process by which plants transform light energy into chemical energy to synthesize glucose and oxygen. Photoperiodism is responsible for the control of flowering, seed germination, and other developmental processes and is considered as the plant response to the length of day and night

Water

Water maintains cell turgor and hence keeps the cells turgid, providing the plant with the erect form it holds. Water further acts as a solvent that acts in nutrient translocation between different parts of the plant through the xylem and phloem.

Effects of Water Deficiency and Excess

Water Deficiency: It results in wilting, stunted growth, and hampers physiological activities.
Water Excess: Root rotting, oxygen lack in the soil, and inhibition of nutrient uptake.

Temperature

Temperature essentially changes the rate at which the enzymatic activities within the plants occur, affecting the growth and development of organisms. The optimal temperature ranges allow the maximum efficiency of the enzymatic activities and growth rate. Temperatures above or below could completely inhibit these functions from occurring altogether.

Nutrients

Plants need some macronutrients, such as nitrogen, phosphorous, and potassium, and other nutrients such as iron, manganese, and zinc, which are micronutrients, for development and to grow. These nutrients have their functionality in the physiological process.

Role of Soil Fertility in Plant Growth

Soil fertility can be defined as a state where soil possesses all the required nutrients for plant growth. Such a soil with required nutrients will support the profuse growth of plants by developing a healthy competent root system that can pick up the required nutrients from the environment at a fast rate.

Differentiation

It is a process by which non-specialised cells get to be specialized to perform distinct functions.
It is the process of development which is important to develop most tissues and organs of plants. This gives way to complex structures and functions.

Mechanism of Differentiation

It is brought by both factors of genetic regulation and environmental signals.

Cell Shape and Size Changes

Collenchyma Cells: They provide support and elasticity to young stems and leaves, respectively.
Sclerenchyma Cells: They provide mechanical support and strength with thick and lignified cell walls.

Differentiation in Root and Shoot Systems

Roots: Development of root hairs that finally allow the absorption of water and its related nutrients.
Shoots: Differentiation processes that lead to the development of leaves, flowers, and fruits, and in transport tissue.

Role of Differentiation in Plant Growth and Development

Leads to the formation of specialised structures like leaves, stems, and roots; in further vascular plants, it also leads to reproductive organs.
A means of adjustability to the environment, where cell differentiation enables the plant to develop its cells of a particular kind

Examples of Differentiation

Vascular Tissue: xylem cells differentiate to conduct water and minerals while conducting sugars and other organic compounds is done by the phloem.
Specialised leaves: These leaves have mesophyll cells differentiated into palisade parenchyma for photosynthesis and spongy parenchyma for gas exchange.

NCERT Solutions Subject-wise link:

Plant Growth and Development Regulators

Some important growth regulators of plants are discussed below with their specific roles mentioned along with them.

Plant Growth Regulators	Explanation
Auxin	Helps in cell elongation root initiation and apical dominance.
Cytokinin	Stimulates the cell division and works as anti anti-ageing factor in the leaves. Also promotes shoot formation
Gibberellins	Encourages stem elongation seed germination and flowering. Plays a very vital role in breaking down dormancy and promoting growth.
Abscisic Acid (ABA)	Acts as a growth inhibitor, promotes dormancy and also works as a stress respondent in the drought.
Ethylene	Is responsible for fruit ripening, leaf abscission and stress responses in the plant.

NCERT Notes Subject Wise Link:

Tips, Tricks, and Strategies to Prepare for Plant Growth and Development

It's hard to remember everything in a single go. We made the entire problem easy. Some of the tricks regarding Plant growth and Development are given below which you can use to memorize the important points.

Phases of Plant Growth

FEDC

F: Formative Phase (Cell division through mitosis)
E: Enlargement Phase (Cell growth, water absorption, vacuole formation)
D: Differentiation Phase (Cells attain specific structure and function)
C: Cell Maturation (Enlarged cells reach full shape and function)

Factors Affecting Plant Growth

LWTN

L: Light (Photosynthesis, flowering, stomatal movement)
W: Water (Hydration, nutrient transport, photosynthesis)
T: Temperature (Affects photosynthesis, germination, transpiration)
N: Nutrients (Macronutrients like N, P, K, micronutrients like Fe, Cu)

Plant Growth Regulators

AGECE

A: Auxin (Cell elongation, root initiation, apical dominance)
G: Gibberellins (Stem elongation, seed germination, breaking dormancy)
E: Ethylene (Fruit ripening, leaf abscission, stress response)
C: Cytokinin (Cell division, shoot formation, delay leaf aging)
E: Abscisic Acid (ABA) (Promotes dormancy, stress response, inhibits growth)

NCERT Exemplar Solutions Subject-wise link:

Types of Questions Asked on Plant Growth and Development

The table given below indicates the weightage and types of questions asked from plant growth and development in exams:

Exam Type	Types of Questions	Weightage
CBSE	Short answer questions on plant hormones, phases of growth, seed germination, and factors affecting plant growth.	5-6%
NEET	MCQs cover plant hormones (auxins, gibberellins, cytokinins, etc.), photoperiodism, vernalization, and growth curves.	3-4%
AIIMS	Assertion and reason questions on plant growth regulators, tropic movements, and factors affecting development.	3-4%
Nursing Entrance Exams	Scenario-based questions on plant growth patterns, hormonal control of development, and the use of plant hormones in healthcare.	2-3%
Paramedical Exams	True/False and MCQs on plant growth stages, roles of hormones, dormancy, and development-related processes.	1-3%

Prescribed Books for Plant Growth and Development

The main and most recommended learning resource for plant growth and development is the NCERT Biology class 11 textbook covering all concepts as per the CBSE syllabus. For further understanding, "Trueman's Elementary Biology, Volume 1" can be referred to. The other useful book is "Pradeep's Biology" which is also known for its detailed explanation and plenty of solved examples. You can access a variety of videos, articles and mock tests on this chapter from the careers360 platform. These books along with proper practice will help a lot for board exams as well as competitive exams like NEET.

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