Class 11 Biology - ODISHA
Plant Growth and Development
The chapter 'Plant Growth and Development' in Class 11 Biology explores the irreversible permanent increase in size, mass, and volume of plants, driven by cellular division and elongation. Students will study the unique indeterminate growth of plants, meristems, phases of growth, and the crucial roles played by plant growth regulators (PGRs) like auxins, gibberellins, cytokinins, ethylene, and abscisic acid. Additionally, the chapter covers photoperiodism, vernalization, and seed dormancy, which regulate flowering and seasonal responses. For Odisha BSE board exams, this is a high-scoring unit with frequent questions on plant hormone functions, physiological processes, and curve characteristics.
Start Learning FreeKey Concepts
Plant Growth
An irreversible, permanent increase in size, volume, or dry weight of an organism, primarily driven by mitotic cell division in meristematic regions.
Sigmoid Growth Curve
The characteristic S-shaped curve of plant growth consisting of a lag phase, log (exponential) phase, and a stationary phase as nutrients become limiting.
Differentiation, Dedifferentiation, and Redifferentiation
Differentiation is when cells mature to perform specific tasks; dedifferentiation is when mature cells regain division capacity (like interfascicular cambium); redifferentiation is when these cells lose division capacity again to form secondary tissues.
Plant Growth Regulators (PGRs)
Chemical substances like Auxin, Gibberellin, Cytokinin, Ethylene, and Abscisic Acid that act as plant hormones to control various developmental stages and stress responses.
Photoperiodism
The physiological response of plants to the relative lengths of light and dark periods (day length) that triggers flowering.
Important Formulas
Board Exam Info
In the Odisha (BSE) Class 11 Biology examinations, this chapter typically carries around 6-8 marks. Students frequently encounter 2-mark short answer questions on the functions of plant hormones (like Auxins and Gibberellins), differentiation processes, and short notes on photoperiodism, along with 3-mark or 5-mark descriptive questions explaining the phases of growth or the sigmoid growth curve.
Frequently Asked Questions
What is the difference between indeterminate and determinate growth?
Indeterminate growth means the plant continues to grow throughout its life due to the presence of meristems, while determinate growth stops after reaching a certain size, typical of leaves, flowers, and fruits.
Which plant hormone is known as the 'stress hormone'?
Abscisic Acid (ABA) is called the stress hormone because it increases plant tolerance to various kinds of stresses, particularly water stress or drought, by inducing stomatal closure.
What is the role of vernalization in plants?
Vernalization is the dependence of certain plants, such as winter varieties of wheat and barley, on a cold treatment or low-temperature exposure to promote or accelerate flowering.
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