Plant growth and development practice · Mixed difficulty

Option A (Plasticity) is correct because plasticity refers to the ability of plants to alter their development and morphology in response to environmental conditions.

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 C (Leaves) is correct because leaves contain photoreceptors like phytochromes and cryptochromes that perceive light signals and initiate photomorphogenic responses.

Option A (Auxins) is correct because auxins are responsible for phototropism, the bending of plants towards light.

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

The correct answer is B (It increases rate of cellular respiration causing more production of ATP molecules thus facilitating active water absorption) because auxin promotes cell growth, which requires energy in the form of ATP, leading to increased water absorption to maintain turgor.

Option A (Larkspur and Buttercup) is correct because Larkspur and Buttercup are known examples of plants exhibiting heterophylly as a form of plasticity.

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.

The correct answer is D (Both (A) and (R) are false) because both plant growth and development are linked to water status, and the reason is a correct explanation for growth but not for development.

Option A (Maize) is correct because maize does not typically exhibit plasticity, meaning it doesn't significantly alter its morphology in response to environmental conditions.

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 A is correct because ethylene promotes root hair formation, which increases the surface area for absorption.

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

Option A (Inhibit growth of root) is correct because ethylene generally promotes root growth and root hair formation, not inhibition.

Option A (Buttercup) is correct because buttercup exhibits plasticity induced by different habitats, showing different leaf forms in aquatic and terrestrial environments.

Option A (Auxin) is correct because F.W. Went isolated auxin from the tips of coleoptiles of oat seedlings.

Option C (Elongation) is correct because the cells just proximal to the meristematic zone are typically undergoing elongation, increasing in size before maturation.

Option A is correct because environmental signals like light and gravity do affect growth phases, and this is often mediated by differential auxin concentration.

Option B (Bolting) is correct because bolting is the elongation of the stem in plants with a rosette habit.

Option C (Dedifferentiation) is correct because it refers to the process where differentiated cells revert to an undifferentiated state, forming callus.

Option A (Plant retains the capacity for unlimited growth) is correct because plants have meristematic tissues that allow for continuous growth throughout their life.

Option B (Sigmoid curve) is correct because growth plotted against time typically results in a sigmoid or S-shaped curve.

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.

Option C (Protoplasm) is correct because growth at the cellular level primarily involves an increase in the amount of protoplasm, which includes all the living components of the cell.

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.