Q.Give a detailed account of Calvin cycle with illustration.

The primary CO2 acceptor in C3 plants is RuBP (ribulose-1,5-bisphosphate); its carboxylation by RuBisCO yields 3-PGA as the first stable product of the Calvin (C3) cycle.

C3 plants (the majority of plants) fix atmospheric CO2 directly through the Calvin cycle, which has three stages:

1. Carboxylation: CO2 is fixed by combining with the 5-carbon compound RuBP (ribulose-1,5-bisphosphate), catalysed by the enzyme RuBisCO (ribulose bisphosphate carboxylase-oxygenase). This is the rate-limiting and most crucial step.
2. This reaction produces an unstable 6-carbon intermediate that immediately splits into two molecules of the 3-carbon compound 3-phosphoglycerate (3-PGA) — the first stable product of the cycle (this is why the pathway is called the C3 pathway).
3. Reduction: 3-PGA is reduced to G3P (glyceraldehyde-3-phosphate) using ATP and NADPH from the light reactions.
4. Regeneration: Most G3P is used to regenerate RuBP so the cycle can continue; a fraction is used to synthesise glucose/starch. …

The dark reaction (Calvin cycle / carbon-fixation reaction) of photosynthesis occurs in the stroma of the chloroplast.

A chloroplast has two main compartments: the membranous thylakoid system (where the light reaction occurs) and the stroma, the enzyme-rich fluid matrix surrounding the thylakoids. The dark reaction (also called the biosynthetic or carbon-fixation phase, i.e. the Calvin cycle) does not directly need light and takes …

This statement is True: RuBisCO fixes CO2 onto RuBP to directly yield two molecules of 3-phosphoglyceric acid (3-PGA), the first stable product of the Calvin (C3) cycle.

The Calvin cycle (also called the C3 cycle, since its first product has three carbons) begins with carboxylation: the enzyme RuBisCO (ribulose bisphosphate carboxylase-oxygenase) catalyses the fixation of one molecule of atmospheric CO2 onto ribulose-1,5-bisphosphate (RuBP), a 5-carbon sugar. This forms an unstable 6-carbon intermediate that immediately splits into two molecules of 3-phosphoglyceric acid (3-PGA), each containing three carbon atoms. This is why plant …

The dark reaction (carbon-fixation / Calvin cycle) of photosynthesis occurs in the colourless matrix of the chloroplast called the stroma.

A chloroplast has two main functional compartments:

• The grana (stacks of thylakoid membranes) — the site of the light reaction, where light energy is trapped and converted to ATP and NADPH, and water is split (photolysis). …

RuBP is the CO2 acceptor in C3 plants.

In C3 (Calvin) cycle, CO2 is fixed onto the 5-carbon acceptor RuBP (ribulose-1,5-bisphosphate) by the enzyme RuBisCO, forming two molecules of 3-carbon PGA. Hence RuBP is the primary CO2 acceptor in C3 plants (PEP is the …

Just as the light reaction of photosynthesis occurs in the grana (thylakoid membranes) of the chloroplast, the dark reaction (carbon-fixation phase) occurs in the stroma.

The chloroplast has two main functional compartments: the membrane-bound grana (stacks of thylakoids), where the light-dependent reactions — trapping light energy, splitting water, and producing ATP and NADPH — occur; and the stroma, the fluid matri …

The Calvin cycle's three phases are carboxylation, reduction, and regeneration; photophosphorylation belongs to the light reaction.

The Calvin cycle (C3 cycle, the biosynthetic/dark phase of photosynthesis) proceeds in three stages:

1. Carboxylation -- CO2 is fixed onto RuBP by the enzyme RuBisCO, forming two molecules of 3-PGA.
2. Reduction -- 3-PGA is reduced to G3P using the ATP and NADPH generated by the light reaction.
3. Regeneration -- most G3P is used to regenerate RuBP so the cycle can continue, while a fraction is used to synthesise glucose/starch. …

Carboxylation of RuBP by RuBisCO produces two molecules of 3-phosphoglyceric acid (3-PGA), the first stable product of the Calvin cycle.

The Calvin cycle (C3 pathway) begins with carboxylation: the enzyme RuBisCO fixes one molecule of atmospheric CO2 onto the 5-carbon sugar ribulose-1,5-bisphosphate (RuBP). This forms an unstable 6-carbon intermediate that immediately breaks down into two molecules of the 3-carbon compound 3-phosphoglyceric acid (3-PGA) — hence the name 'C3 pathway'. 3-PGA is then reduced (using ATP and NADPH from the light reaction) to glyceraldehyde-3-phosphate, some of which regenerates RuBP …

'Stroma' matches 'Fixation of CO2' — the stroma is the site of the Calvin cycle (dark reactions), where atmospheric CO2 is fixed into organic compounds.

A chloroplast has two main functional compartments: the thylakoid membranes (stacked as grana), where the light reactions occur (light absorption, water splitting, ATP and NADPH generation), and the stroma, the protein-rich fluid matrix surrounding the thylakoids. The stroma contains the enzymes (including RuBisCO) needed for the Calvin cycle (C3 cycle), in which CO2 from the atmosphere is fixed onto RuBP and, using …