Class 11 Biology - HARYANA
Plant Growth and Development
The chapter 'Plant Growth and Development' in Class 11 Biology explores how plants grow, differentiate, and respond to internal and external stimuli. Students learn about indeterminate growth, plant growth regulators like auxins, gibberellins, cytokinins, ethylene, and abscisic acid, along with photoperiodism and vernalization. This chapter is vital for Haryana (BSEH) board exams as it frequently features conceptual questions on hormone functions and physiological processes. Mastering this topic helps build a strong foundation for understanding plant physiology, which carries significant weight in both board exams and competitive tests like NEET.
Start Learning FreeKey Concepts
Plant Growth
An irreversible, permanent increase in size, dry weight, or volume of an organ or its parts, driven mainly by mitotic cell division and elongation.
Differentiation and Dedifferentiation
Differentiation is when cells derived from root and shoot apical meristems mature to perform specific functions. Dedifferentiation is the temporary ability of mature cells to regain division capacity, forming new meristems like interfascicular cambium.
Plant Growth Regulators (PGRs)
Small, simple molecules of diverse chemical composition (like auxins, gibberellins, cytokinins, ethylene, and ABA) that act as plant growth promoters or inhibitors.
Photoperiodism
The physiological response of plants to the relative lengths of light and dark periods (photoperiods) for flowering, categorized into short-day, long-day, and day-neutral plants.
Vernalization
The dependence of certain plants, such as winter varieties of wheat and barley, on a low-temperature exposure to quantitatively or qualitatively promote flowering.
Important Formulas
Board Exam Info
In the Haryana (BSEH) Class 11 Biology board exams, this chapter typically carries around 4 to 6 marks. Questions usually include 1-mark objective questions, 2-mark short answers on the physiological effects of plant hormones, and 3-mark descriptive questions on photoperiodism or the phases of plant growth.
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. Determinate growth means organs stop growing after reaching a certain size, like 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 stress, particularly water stress, by inducing stomatal closure.
Why is ethylene considered unique among plant hormones?
Ethylene is a gaseous plant growth regulator that promotes fruit ripening, senescence, and transverse or isodiametric growth in seedlings, unlike other mostly solid or liquid PGRs.
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