Question

Assertion: Action spectrum of photosynthesis compares well with the absorption spectrum.
Reason: Chlorophyll a is the only pigment which can absorb and convert light energy into chemical energy.

• A. If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion
• B. If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion
• C. If Assertion is true but the Reason is false
• D. If both Assertion and Reason are false

Answer 1

Answer: (A)

An absorption spectrum is a measure of the extent to which a given substance absorbs the light of different colours or wavelengths. An action spectrum is the measure of the efficiency of a process induced by light of different wavelengths but of the same intensity. It is actually a plot of the extent of a response (such as photosynthesis) against different wavelengths of light. A comparison of an action spectrum with the absorption spectrum of a pigment indicates whether or not the pigment is involved in the response. For example, the absorption spectrum of chlorophyll a is very similar to the action spectrum of photosynthesis in most plant tissues. Although, light energy is absorbed by chlorophyll as well as by other accessory pigments, only chlorophyll a participates in conversion of light energy to chemical energy.