$CO_2$ is formed in all of the following except:

$A-$ In chloroplast,the membrane system is responsible for trapping the light energy and also for the synthesis of $ATP$ and $NADPH$. This is called the light reaction.
$R-$ In the stroma,enzymatic reactions incorporate $CO_2$ into the plant,leading to the synthesis of sugar.

The importance of photosynthesis is due to

According to one estimate,how many $kg$ of carbon is fixed in the biosphere through photosynthesis annually?

When green algae are illuminated,motile aerobic bacteria usually accumulate near them. This is because,bacteria

$85-90\%$ of all photosynthesis of the world is carried out by