Class 11 Biology - UP
Plant Growth and Development
The chapter 'Plant Growth and Development' in Class 11 Biology explores the irreversible permanent increase in size, differentiation of cells, and the role of plant growth regulators (PGRs) like auxins, gibberellins, cytokinins, ethylene, and abscisic acid. For Uttar Pradesh (UPMSP) board exams, this chapter is extremely important as it includes high-scoring structural questions, diagrams of plant hormone effects, and conceptual problems related to photoperiodism and vernalization. Mastering this chapter helps students understand how plants respond to internal and external environmental cues throughout their life cycle from seed germination to senescence.
Start Learning FreeKey Concepts
Plant Growth
An irreversible, permanent increase in size of an organ or its parts, accompanied by an increase in dry weight and protoplasm.
Phases of Growth
The three main phases of plant growth are meristematic (constant cell division), elongation (cell enlargement and vacuolation), and maturation (cell differentiation).
Plant Growth Regulators (PGRs)
Chemical substances synthesized by plants that influence physiological processes; categorized into promoters (auxins, gibberellins, cytokinins) and inhibitors (abscisic acid, ethylene).
Photoperiodism
The physiological response of plants to the relative lengths of light and dark periods, classified into short-day plants, long-day plants, and day-neutral plants.
Vernalization
The dependence of certain plants on a low-temperature stimulus to flower or undergo vegetative development.
Important Formulas
Board Exam Info
In the Uttar Pradesh (UPMSP) Class 11 Biology examination, this chapter typically carries around 5 to 7 marks. Questions frequently include short answer questions on plant hormones and their physiological functions, differences between arithmetic and geometric growth, and long answer questions explaining photoperiodism or vernalization.
Frequently Asked Questions
What are the major plant growth regulators and their functions?
The five major PGRs are Auxins (apical dominance), Gibberellins (stem elongation), Cytokinins (cell division), Ethylene (fruit ripening), and Abscisic Acid (stress tolerance and dormancy).
What is the difference between arithmetic and geometric growth?
In arithmetic growth, only one daughter cell continues to divide while the other differentiates, resulting in a linear curve. In geometric growth, both progeny cells continue to divide, producing an exponential curve.
What is plasticity in plants?
Plasticity is the ability of plants to follow different pathways in response to environment or phases of life to form different kinds of structures, such as heterophylly in cotton and buttercup.
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