Question

The absorption peak of photosystem I and photosystem II is at

• A. 580 nm and 600 nm, respectively
• B. 640 nm and 660 nm, respectively
• C. 680 nm and 700 nm, respectively
• D. 700 nm and 680 nm, respectively

Answer 1

The correct option is D 700 nm and 680 nm, respectively

Pigments, in photosynthesis, are substances that have the ability to absorb light at specific wavelengths. They are located in the thylakoid membrane of chloroplast. The pigments are organised into LHC (Light Harvesting Complex) and are located within the photosystem I and II. Hence, each photosystem has several pigments. A single chlorophyll a molecule in the centre of photosystem forms the reaction centre. Reaction centre is surrounded by several accessory pigments that protect the reaction centre.

In photosystem l, the reaction centre has an absorption peak at 700 nm (red light), hence is called P700 and in PS ll, the reaction centre has an absorption peak at 680 nm (red light), hence is called P680.