Question

Consider the following phenomena:

1. Closing of leaves of touch-me-not plant on touching.
2. Growth of plants towards light.

Which of them is a response to stimulus?

• A. Only 1
• B. Only 2
• C. Both 1 and 2
• D. Neither 1 nor 2

Answer 1

The correct option is C Both 1 and 2

Movement in touch-me-not plant is non-directional, which means the response is independent of the direction of the stimulus, touch. Growth towards light, gravity or water are directional movements i.e., either towards or away from stimulus. In both cases, the movements are response to stimuli.