Plant growth and development practice · Mixed difficulty

Option A is correct because 2,4-D (2,4-Dichlorophenoxyacetic acid) is a synthetic auxin widely used as a selective herbicide.

The correct answer is D (GA) because gibberellic acid can sometimes substitute for the cold requirement in vernalization, inducing flowering.

Option A (2, 4 – D) is correct because 2,4-D is a synthetic auxin that is selectively toxic to dicotyledonous plants, making it useful as a herbicide.

Option D (Produced by growing apices of stem, which migrate to the region of its action) is correct because auxin is synthesized in the apical meristems and transported basipetally to other plant parts.

Option A is correct because all Gibberellins (GAs) are acidic in nature, while tomatoes are short-day plants.

Option B (ABA) is correct because Abscisic Acid (ABA) is a well-known natural growth inhibitor in plants.

Option A (Plasticity) is correct because plasticity refers to the ability of an organism to produce different kinds of structures at different phases of life or in response to environmental conditions.

Option B (Both Assertion and Reason are true and Reason is not the correct explanation of Assertion) is correct because the assertion is true that not all cells can dedifferentiate, and the reason is also true about the definition of dedifferentiation, but the reason doesn't explain why the assertion is true.

Option B (${\mathrm{C}_2}{\mathrm{H}_4}$) is correct because respiratory climacteric, a burst in respiration rate during fruit ripening, is associated with ethylene.

Option C (Meristems) is correct because meristems are regions in plants where active cell division occurs, leading to the formation of new cells and plant growth.

Option A (Acidic) is correct because gibberellins are carboxylic acids.

Option B (ABA) is correct because Abscisic Acid (ABA) is known as the stress hormone due to its role in plant responses to stress conditions like drought, salinity, and cold.

Option A (The growing apical bud inhibits the growth of the lateral (axillary) buds) is correct because apical dominance is the phenomenon where the apical bud suppresses the growth of lateral buds.

The correct answer is C (Auxins - Isolated from corn - Kernels and coconut milk) because while coconut milk contains cytokinins, auxins are not primarily isolated from corn kernels and coconut milk.

The correct answer is A (Application of high temperature) because vernalization, the process of low-temperature induction of flowering, can be reversed by applying high temperatures.

Option A (I and II) is correct because cytokinins delay leaf senescence and auxins are involved in apical dominance.

The correct answer is C (Spring variety is planted in spring while the autumn variety is planted in autumn) because the planting time is the primary difference between spring and autumn rye varieties.

Option C (Gerontology) is correct because gerontology is the study of aging, including senescence in plants.

Option B (Auxin) is correct because auxin is the plant hormone responsible for apical dominance, where the apical bud inhibits the growth of lateral buds.

Option D ((i) and (iii)) is correct because the twin characteristics of growth are an increase in mass and an increase in the number of individuals.

Option C (A-apical, B-lateral, C-lateral) is correct because apical dominance involves the apical bud inhibiting lateral bud growth, and removing the apical bud promotes lateral bud growth.

Option D (All of these) is correct because plant growth regulators are also known as plant growth substances, plant hormones, and phytohormones.

The correct answer is D (Autonomic movement of growth) because the opening of floral buds into flowers is a self-generated (autonomic) movement resulting from growth processes within the plant.

Option D (Plant growth ceases) is correct because meristematic cells are responsible for cell division and growth; if they stop dividing, growth stops.

The correct answer is A (Lower temperature) because vernalization requires exposure to a period of low temperature to promote flowering.

Option C (Abscisic acid) is correct because ABA promotes bud dormancy, stomatal closure, abscission layer formation, and is an antagonist to GA.

The correct answer is D (Both (1) and (2)) because both the shoot apex and the embryo of the seed can perceive the stimulus for vernalisation.

Option B (Photoperiodism) is correct because photoperiodism is the response of plants to the relative lengths of day and night, especially in relation to flowering.

The correct answer is B (Induction of seedless fruits in grapes) because Gibberellins are used to induce parthenocarpy (seedless fruit development) in grapes.

Option B (Abscission) is correct because abscission is the process of shedding leaves, flowers, or fruits due to hormonal changes.