Question

Assertion: A defoliated plant can respond to photoperiodic stimulation.

Reason: It is the shoot apices that perceive light to induce flowering.

Select the appropriate option:

• A. Both assertion and reason are correct statements and the reason is the correct explanation of the assertion
• B. Both assertion and reason are correct statements but the reason is an incorrect explanation of the assertion
• C. Only assertion is correct
• D. Both assertion and reason are incorrect

Answer 1

The correct option is D Both assertion and reason are incorrect

Photoperiodic stimulation or photoperiodism is defined as the response by an organism to the lengths of day and night. Leaves are considered to be the site of perception for photoperiodic stimulation. A defoliated plant i.e. a plant without leaves will not be able to respond to light. Hence, the assertion is incorrect.

It has been observed that a lot of plants need periodic exposure to light to induce flowering. As it is the shoot apices of plants that modify themselves to flowering apices just before flowering. But these shoot apices by themselves do not perceive photoperiod. It is believed that a hormone is responsible for flowering. This hormone is transported from leaves to the shoot apices once the plant is exposed to adequate inductive photoperiod. Thus, it is not the shoot apices that perceive light to flower. Hence, the reason is also incorrect.