# What two types of reactions occur in photosynthesis?

Jan 30, 2018
1. Light dependent reactions

2. Dark reactions Light or independent reactions.

#### Explanation:

The process of photosynthesis is basically divided into two steps i.e Light reactions and dark reactions ( known as Calvin cycle or ${C}_{3}$ pathway).

Breif concept to these is $2$processes is as follows:

Light reactions happens during daytime only. During light reactions, the sunlight energy is trapped and absorbed by photosynthetic pigments that are arranged to form photosystems. These photosystems are present in thylakoid membranes of chloroplast. This absorbed energy is converted into chemical energy of $A T P$ and $N A D P H$. Oxygen is released during non-cyclic photophosphorylation as a result of photolysis.

Dark reactions to not require light and can take place in the presence or absence of light. In these reactions, sugars are produced in stroma of chloroplast. using the assimilatory power("ATP & NADPH") produced during light reactions and carbon dioxide. Dark reactions can be summarized as:

$3 C {O}_{2}$ + $6 N A D P H$ + $9 A T P \to {\left(C {H}_{2} O\right)}_{3}$ + $6 N A D P H$ +
$9 A D P$ +$9$Pi

Hope it helps...