Question

Darwin and Darwin discovered that Canary Grass coleoptile bends towards light only when

• A. It is $5$ $cm$ long
• B. The seedling is growing in blue light
• C. Coleoptile tip is intact and exposed to light
• D. Nights are cooler

Answer 1

Answer: (C)

Coleoptile tip is intact and exposed to light

Charles Darwin and Francis Darwin discovered that the phototropic stimulus is detected at the tip of the plant. In their experiment, they used canary grass which was protected by coleoptile. After sometime, the coleoptile stoped growing and the primary leaf comes out of it. Hence, it was discovered that the tip of the coleoptile was the stimulus for phototropism and bending towards light.

Thus, the correct answer is option C.