Question

Etiolated seedlings are produced by germinating seeds and keeping them in total darkness. Under which of the following conditions will plants kept in the dark-begin to synthesize chlorophyll ?

• A. After being given a pulse of blue light
• B. After being given a pulse of red light
• C. After being given a pulse of red light followed by a pulse of far-red light
• D. After being given a pulse of far-red light followed by a pulse of red light

Answer 1

Answer: (C)

The pulse of red light converts $P_r$ to $P_{fr}$. Subsequent pulses of far-red light stimulate changes that lead to chlorophyll synthesis.