Question

The first step in dark reaction of photosynthesis is

• A. Formation of ATP
• B. Attachment of carbon dioxide to a pentose sugar
• C. Excitement of an electron of chlorophyll by photon of light
• D. Ionisation of water

Answer 1

The correct option is B Attachment of carbon dioxide to a pentose sugar

The dark reaction of photosynthesis is not dependent on sunlight but it does not mean it does not occur in its presence. The dark reaction occurs both in the presence and absence of sunlight. This reaction occurs in the stroma of the chloroplasts which are cell organelles known as the kitchen of the cells. The CO2 taken in by the plant combines a 5 carbon compound known as ribulose 1,5- biphosphate to form two molecules of 3-phosphoglycerate(3PGA). This step is catalyzed by the enzyme ribulose biphosphate carboxylase or RUBISCO(RuBp).

So, the correct option is 'Option B'.