NEET BIOLOGY

Detailed explanation-1: -The gaseous hormone ethylene plays a key role in plant growth and development, and it is a major regulator of stress responses. It inhibits vegetative growth by restricting cell elongation, mainly through cross-talk with auxins.

Detailed explanation-2: -It acts at trace levels throughout the life of the plant by stimulating or regulating the ripening of fruit, the opening of flowers, the abscission (or shedding) of leaves and, in aquatic and semi-aquatic species, promoting the ‘escape’ from submergence by means of rapid elongation of stems or leaves.

Detailed explanation-3: -Abscisic acid is a hormone which inhibits growth. It is responsible for wilting of leaves, dormancy of seeds and buds and inhibition of seed germination and development. Hence it is not associated with the growth of plants. Auxin, gibberellins and cytokinins are plant hormones associated with the growth of plants.

Detailed explanation-4: -Ethylene and Auxin Hormonal coordination is an important aspect, which regulates leaf growth processes. Auxin induces ethylene production, and many effects of exogenous auxins are, in fact, ethylene responses (Abeles et al., 1992).