NEET BIOLOGY

Detailed explanation-1: -The movement of the plant towards the response of gravity pull is known as geotropism. THe roots of the plant show positive stimuli as they grow in the direction of gravity and the stem reflects negative stimuli as it grows in the opposite direction.

Detailed explanation-2: -In plants, the general response to gravity is well known: their roots respond positively, growing down, into the soil, and their stems respond negatively, growing upward, to reach the sunlight.

Detailed explanation-3: -Graviperception by plant roots is believed to occur via the sedimentation of amyloplasts in columella cells of the root cap. This physical stimulus results in an accumulation of calcium on the lower side of the cap, which in turn induces gravicurvature.

Detailed explanation-4: -The reason plants know which way to grow in response to gravity is due to amyloplasts in the plants. Amyloplasts (also known as statoliths ) are specialized plastids that contain starch granules and settle downward in response to gravity.