Plant growth and development practice · Medium

The correct answer is A (13 hours light, 11 hours dark) because for a plant with a 13-hour critical day length, flowering will occur if the light period is equal to or less than the critical day length. Since the question is not specifying if the plant is a long-day or short-day plant, we assume it is a long-day plant.

Option D (If both Assertion and Reason are false) is correct because apical dominance is decreased, not increased, by removing the shoot tip, and the inhibition is due to auxin produced in the apical bud, not its accumulation in lateral parts after removal.

Option B is correct because W1 represents the final size, W0 the initial size, r the growth rate, and t the time of growth in the geometrical growth equation.

Option D (Both (a) and (b)) is correct because sleep movements in plants are nastic responses triggered by daily changes in both light and darkness.

Option D (I and II) is correct because cytokinins delay senescence and auxins regulate apical dominance.

The correct answer is D (Delay senescence by GA) because Gibberellins (GA) can delay senescence in fruits, allowing them to be left on the tree longer and increase the market period.

Option C (Outward movement of protons) is correct because the proton pump uses ATP to actively transport protons out of the guard cells, creating an electrochemical gradient that drives potassium uptake.

Option A (I, IV only) is correct because growth and differentiation in higher plants are open, and a defoliated plant cannot respond to the photoperiodic cycle.

Option B (Amino purines) is correct because cytokinins are primarily adenine derivatives, which are amino purines, playing a crucial role in cell division and differentiation.

The correct answer is C (Induce dormancy) because gibberellins typically break dormancy, while inducing dormancy is a function of abscisic acid (ABA).

Option A (Growth regulators) is correct because growth regulators are intrinsic factors influencing plant development.

The correct answer is D (Both (a) and (c)) because vernalization shortens both the reproductive and vegetative phases by inducing early flowering.

Option B (2) is correct because ethylene's promotion of seed/bud dormancy breaking and germination initiation are antagonistic to abscisic acid's (ABA) role in promoting dormancy.

Option A (If both the assertion and the reason are true and the reason is a correct explanation of the assertion) is correct because plants' unlimited growth is directly due to the presence of meristematic tissues at specific locations.

Option D (Exponential growth phase) is correct because the grand phase of growth is another name for the exponential growth phase.

Option A is correct because auxin promotes cell elongation on the shaded side of the shoot, causing it to bend towards the light source.

Option B (5) is correct because 2 to the power of 5 equals 32, representing 5 generations of cell division.

Option C (Redifferentiation) is correct because phellem formation by phellogen involves cells that have already differentiated, then dedifferentiated to become phellogen, and are now differentiating again into phellem.

Option C (Canary grass) is correct because Charles Darwin and Francis Darwin conducted their phototropism experiments specifically on canary grass coleoptiles.

Option A (Acidic in nature) is correct because auxin, which is used to increase sugarcane yield, is acidic in nature (e.g., IAA).

Option D (IAA) is correct because Indole-3-acetic acid (IAA) is the most common naturally occurring auxin in plants, synthesized from tryptophan.

The correct answer is D (Short day) because the plant flowered under 12 hours of light and 12 hours of night, but did not flower when the night phase was interrupted by a flash of light, indicating it requires an uninterrupted long night to flower, which is characteristic of short-day plants.

The correct answer is A (Autoclaved herring sperm DNA) because kinetin was first discovered from this source as a modified form of adenine.

The correct answer is C (If Assertion is true but Reason is false) because "touch" responses in Mimosa pudica are nastic movements, but nastic movements are non-directional, meaning they don't occur in the direction of the stimulus.

Option A (α-amylase) is correct because α-amylase breaks down starch into sugars, providing energy for germination.

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

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 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.