Question

Explain dark reaction of photosynthesis class 10

Answer 1

1) Dark reaction do not require light energy and occur simultaneously with light reaction. ■ .
2) Dark reaction do not depend on light.
3) Dark reaction occur in the stroma region of chloroplast.
4) H+ ions produced in photolysis are immediately picked up by special compound NADP to form NADPH.
5) In the dark phase, the hydrogen of the NADPH is used to combine it with and to ultimately produce glucose
6) This synthesis occurs in a number of steps using certain special intermediate compounds (mainly Ribulose bi phosphate) and enzymes.
7) Finally glucose converted into starch.

Answer 2

$\textbf{Photosynthesis}$:

6CO2 + 12H2O --chlorophyll,sunlight--> C6H1206 + 6O2 + 6H2O

It is the process by which green plants and some other organisms uses sunlight to synthesise nutrients from carbon dioxide and water. The main products forms here is glucose and by products are carbon dioxide and oxygen and water where which chlorophylls are the sites of photosynthesis.

Events occurring during Photosynthesis are as follows :

1. Absorption of light energy by chlorophyll.

2. Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.

3. Reduction of carbon dioxide to carbohydrates.

Stages of Photosynthesis are as follows :

1. $\textbf{Light Reaction }$:

It occurs in the Grana where photon are absorbed so as to excite electrons of chlorophyll to a higher energy level. These activated electrons are harnessed to form ATP from ADP and reduce NADP to NADPH. Water is also splitted during this and oxygen is released.

2. $\textbf{Dark Reactions }$:

Calvin cycle occurring in chlorophyll here carbon dioxide combined with 5-carbon sugar call ribulose biphosphate. This unstable compound breaks down into three carbon compounds (phosphoglyeric acid) this then forms glucose.