Plant growth and development practice · Mixed difficulty

The correct answer is B (Both Assertion and Reason are true and Reason is not the correct explanation of Assertion) because while both statements are correct, the reason doesn't directly explain why ethylene is a gaseous hormone.

Option C (Phenology) is correct because phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate.

Option D (Cotton, coriander and larkspur) is correct because these plants show heterophylly due to different phases of life.

Option A (Continuously, only up to a certain age) is correct because cell division occurs continuously in plants but only up to a certain age in animals.

Option A (AGR = 14 cm, RGR = 2.8) is correct because the actual growth rate is the difference in length, and the relative growth rate is the ratio of the final length to the initial length.

Option C (Initial slow growth) is correct because the lag phase in geometrical growth is characterized by a slow initial increase in population size.

Option A (I and II) is correct because the phase of maturation is characterized by cells reaching their maximal size and undergoing wall thickening and protoplasmic modification.

Option C (Ecological heterophylly) is the correct answer. Plasticity exhibited by Delphinium is called Ecological heterophylly.

Option B (Meristematic phase of the growth) is correct because constantly dividing cells are characteristic of meristematic tissue, which is found at the root and shoot apices.

Option B (Secondary cortex) is correct because secondary cortex is formed from dedifferentiated cells that have regained the ability to divide, representing redifferentiation.

Option A (GA) is correct because Gibberellic acid (GA) promotes seed germination by breaking seed dormancy.

Option C (Increase in respiration rate) is correct because while respiration rate is related to growth, it is not a direct measurement of growth like the other options.