Question

The hormone that helps plants respond to drought is

(A) auxin.

(B) abscisic acid.

(C) cytokinin.

(D) ethylene.

Short answer

1. The statement “auxin” is false.

2. The statement “abscisic acid” istrue.

3. The statement “cytokinin” is false.

4. The statement “ethylene” is false.

Step-by-step solution

Hormone

The product of living cells, which is released by plant cells to regulate their cellular response by communicating and coordinating between cells, is called hormone.

Explanation of option ‘(A)’

The term auxin refers to a plant hormone located in root and shoot tips that enhance cell elongation.

Thus, cell growth in plants is promoted by auxin.

Therefore, the given statement is false.

Explanation of option ‘(B)’

The isoprenoid plant hormone that aids plants to adapt to stress conditions by increasing plant tolerance is called ABA or abscisic acid.

Thus, plant roots and leaves produce abscisic acid (ABA) in response to water scarcity or drought stress.

Therefore, the given statement is true.

Explanation of option ‘(C)’

The class of plant hormone synthesized in roots and responsible for promoting cell division to control plant growth is called cytokinin. Various cytokinin functions are cell differentiation, inflorescence growth, and cotyledon expansion.

Thus, cytokinin promotes cell division.

Therefore, the given statement is false.

Explanation of option ‘(D)’

The plant growth regulator found in the tissue of ripening fruits and nodes of the stem promoting senescence, abscission, and inducing fruit ripening is ethylene. The several functions performed by the ethylene hormone are stimulating flower opening, bud development, and rapid diffusion.

Thus, fruit ripening is regulated by ethylene.

Therefore, the given statement is false.