Question

Which statement is wrong regarding Photosystem I?

• A. Commonly, it is present in stroma of chloroplast.
• B. It is activated by longer wavelength (above 680nm) of light.
• C. Chlorophyll a to chlorophyll b ratio is less than one.
• D. It is necessary for both cyclic and non-cyclic photophosphorylation.

Hint:

Compare how chlorophyll a and b are distributed between the two photosystems.

Answer 1

The Correct Option is C

Step 1: Photosystem I sits mainly in the stroma-exposed thylakoid membrane (loosely called the stroma lamellae region), so option (A) is considered correct.

Step 2: PSI has its reaction centre P700, activated by far-red light of wavelength above 680 nm, so option (B) is correct.

Step 3: PSI participates in both cyclic photophosphorylation on its own and non-cyclic photophosphorylation along with PSII, so option (D) is correct.

Step 4: PSI actually has a high chlorophyll a to chlorophyll b ratio, much greater than one, since it is richer in chlorophyll a. So the claim that this ratio is less than one is wrong, making (C) the answer.