What is light reaction and dark reaction?

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Answer

Light reactions – As the name suggests, this reaction takes place in the presence of light. Light energy is absorbed by chlorophyll molecules and is utilized for splitting water molecules into hydrogen and oxygen. Additionally in this phase, assimilatory power in the form of ATP and NADPH2 are produced.Light reactions occur in the membranes of thylakoids.Events occurring during light reactions:#Absorption of light energy by chlorophyll molecules#Splitting of water molecules into hydrogen and oxygen atoms#Formation of ATP and NADPH2Dark reactions – This reaction does not require direct light and occurs in the stroma of chloroplasts. During this phase, ATP and NADPH2 (formed during light reactions) are utilized for the reduction of CO2 to carbohydrates (food).Event occurring during dark reaction:#Reduction of CO2to form carbohydrates You will study more about them in higher class

Answer

Light Reaction and Dark Reaction

Photosynthesis is the process by which plants convert light energy into chemical energy in the form of glucose. It is a complex process that takes place in the chloroplasts of plant cells. Photosynthesis is divided into two stages: light reaction and dark reaction.

Light Reaction

The light reaction is the first stage of photosynthesis that occurs in the thylakoid membranes of the chloroplasts. During this stage, light energy is converted into chemical energy in the form of ATP and NADPH. The process involves the following steps:

Light Absorption: The light energy is absorbed by the pigments present in the chloroplasts, primarily chlorophyll.

Electron Transport Chain: The absorbed energy is used to excite electrons, which then travel through a series of protein complexes called the electron transport chain. This results in the pumping of protons from the stroma into the thylakoid lumen, creating an electrochemical gradient.

ATP Synthesis: The electrochemical gradient drives the synthesis of ATP through a process called chemiosmosis.

NADPH Synthesis: The electrons that passed through the electron transport chain are used to reduce NADP+ to NADPH, which is a source of reducing power for the dark reaction.

Dark Reaction

The dark reaction, also known as the Calvin cycle, is the second stage of photosynthesis that occurs in the stroma of the chloroplasts. During this stage, the chemical energy in the form of ATP and NADPH is used to synthesize glucose from carbon dioxide. The process involves the following steps:

Carbon Fixation: Carbon dioxide is fixed into an organic molecule called ribulose bisphosphate (RuBP) through the enzyme Rubisco.

Reduction: The fixed carbon is reduced by ATP and NADPH to form glyceraldehyde-3-phosphate (G3P).

Regeneration: Some of the G3P is used to regenerate RuBP, which is needed for further carbon fixation. The rest of the G3P is used to synthesize glucose and other sugars.

In summary, the light reaction converts light energy into chemical energy in the form of ATP and NADPH, while the dark reaction uses this energy to synthesize glucose from carbon dioxide.

Answer

Photosynthesis is divided into two phase that is light reaction and dark reactionLight reaction :- this reaction takes place in the presence of light hands just I'm as light reaction in this reaction following things happens :1) photolysis of water2)Realse of H+ ion is obtained which further used for dark reactionDark reaction :- this reaction is not dependent on light it may either take place in day as well as in night too.following things happen in dark reaction1) H+ ion obtained from light reaction reacts with a special compound NADP n forms NADPH2) Reduction of CO2 to form Gulucose.HOPE IT WILL HELP YOUTHNqqq

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