Which of the following changes take place in plants by environmental triggers such as light or gravity?

Correct option is B

The correct answer is: (b) Change in the directions that plant parts grow in

Explanation:

• Plants respond to external stimuli like light, gravity, touch, and water by changing the direction in which they grow.

• These directional movements are called tropic movements (e.g., phototropism, geotropism).

• For example, shoots grow towards light (positive phototropism), and roots grow downward in response to gravity (positive geotropism).

• These movements help the plant optimize resource use, like maximizing light absorption or anchoring better in soil.

Information Booster:

• Phototropism – response to light.

• Geotropism – response to gravity.

• Hydrotropism – response to water.

• Thigmotropism – response to touch (e.g., tendrils).

• Auxins – plant hormones play a key role in directional growth.

• These movements are slow and irreversible.

Additional Information:

• Option (a): Shape of leaves/fruits is determined genetically, not by external stimuli like light or gravity.

• Option (c): Size of ovary/anther is related to developmental biology, not a direct response to environmental triggers.

• Option (d): Root branching pattern is influenced by internal programming and nutrients, not directly by gravity/light like tropic responses.