Question

Tropic movements are caused by:

• A. Cell division
• B. Cell elongation
• C. Loss of water
• D. Gain of water

Answer 1

Answer: (B)

Cell elongation

Tropic movement is growth movement shown by plants in response to an external stimulus. The movement depends on the direction of the stimulus. The movement towards the direction of stimuli is called positive tropism, while movement away from stimuli is called negative tropism. The tropic movement is the result of cell elongation. For example, in phototropism, faster cell elongation is seen on the shaded side than on the illuminated side. That is why it appears that the plant is bending towards the light.

Thus, the correct answer is option B.