Question

________ light is absorbed by the reaction centre during light reaction.

• A. Blue
• B. Red
• C. Green
• D. Yellow

Answer 1

The correct option is B Red

Photosynthetic pigments 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 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, it is called P700 and in PS ll, the reaction centre has an absorption peak at 680 nm (red light), hence, it is called P680. Hence, red light is absorbed by the reaction centre of PS-I and PS-II during light reaction.