NEET BIOLOGY

Detailed explanation-1: -The directed growth responses that make the plant to grow in direction of or away from a stimulus are known as tropic movements. Directed growth of plant caused by light is known as phototropism. Gravitropism is growth response of plant in direction of gravity.

Detailed explanation-2: -Gravitropism is an important plant growth response to the environment that directs shoots upward and roots downward, thereby allowing each organ to reach environments that are adequate for performance of their primary functions.

Detailed explanation-3: -Gravitropism appears defective in roots of the starchless mutants, because light from above does not affect the gravitropism of wild-type roots compared with the dark, whereas it does improve the orientation of mutant roots (Table I).

Detailed explanation-4: -One important light response in plants is phototropism, which involves growth toward-or away from-a light source. Positive phototropism is growth towards a light source; negative phototropism is growth away from light.

Detailed explanation-5: -Plants respond directly to Earth’s gravitational attraction, and also to light. Stems grow upward, or away from the center of Earth, and towards light. Roots grow downward, or towards the center of Earth, and away from light.