Question

Which step of photosynthesis uses CO2? Name the process of incorporating CO2 into organic (sugar) molecules.

Answer 1

Photosynthesis is the process in which light engery is converted into chemical energy from CO2 and H​​​​​​2​O. The photosynthesis process not only used by plants but also used by other microorganisms like algae and some photoautotrophic bacteria.

In photosynthesis light capturing is important which is done by Chlorophyll pigment ( light harvesting pigment).

Two Stages in photosynthesis are light dependent reactions and light independent reactions

Light Dependent reactions In this stage, molecule of Chlorophyll absorbs photon of light and losses a electron. In this process energy captured is used for making ATP and NADPH i.e energy storage molecules.

Light Independent reactions In this process Calvin cycle occurs in which CO2 is fixed to produce three carbon sugar molecule by RuBisCo (Ribulose bisphosphate Carboxylase oxygenase) enzyme.

So light independent process of photosynthesis uses the CO2 and process of incorporation of CO2 into molecule of sugar is known as carbon fixation. This three carbon molecule then converted to full carbohydrate molecule.

As shown in figure below how CO2 is fixed to produce 3 phosphoglycerate which later in reaction produce sugar molecule.

numbers in bracket shows number of molecules.

CF 0-2 co ADP C=0 CHOH Stage! Fixation. (co, fixed CHOH Into into rate) Phosphoria Ribulaselg5-bisphosphate Coo ATP (3) Stage 3: Regeneration of acceptor CHO Energy III (1) CHOH Productipo I via Iglycolysis Les sugant Synthebis CHOH CHOD 3-Phospbo glycerata Glyceraldehyde 3 phosphate. Stage 2 Reduction ATP (6) Vi ADP (6) NADPT NADPH+H 6) Calvin -Cycle