NEET BIOLOGY

Detailed explanation-1: -Gravitropism . Plant parts tend to either grow in the same direction as gravity, or in the opposite direction. This type of tropism is called gravitropism. For example, the roots of most plants exhibit positive gravitropism when they grow downward.

Detailed explanation-2: -When the stem grows against the force of gravity (upwards), this is known as a negative gravitropism. When a root grows in the direction of the force of gravity (downwards), this is known as a positive gravitropism.

Detailed explanation-3: -Positive gravitropism occurs when roots grow into soil because they grow in the direction of gravity while negative gravitropism occurs when shoots grow up toward sunlight in the opposite direction of gravity.

Detailed explanation-4: -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-5: -Roots grow downward, or towards the center of Earth, and away from light. These responses to external stimuli are called tropisms. Plants’ growth response to gravity is known as gravitropism; the growth response to light is phototropism. Both tropisms are controlled by plant growth hormones.