Photosynthesis in Plants

Phycocyanobilin is a blue phycobilin, i.e. a tetrapyrrole chromophore found in cyanobacteria and in the chloroplasts of red algae, glaucophytes and some cryptomonads. Phycocyanobilin is present only in the phycobiliproteins allophycocyanin and phycocyanin, of which it is the terminal acceptor of energy.

Pheophytin is a chemical compound that serves as the first electron carrier intermediate in the electron transfer pathway of photosystem II (PS II) in plants and the photosynthetic reaction center (RC P870) found in purple bacteria.

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In 1966, Hatch and Slack reported the C₄ pathway for CO₂ fixation in certain tropical plants. In 1954, Melvin Calvin traced the path of carbon in photosynthesis and gave the C₃ cycle (now known as Calvin cycle).

Dark reaction occurs in stroma of chloroplast. Statement Q is true, but statement S is false.

Carotenoids are very long-chain water-repelling pigments that are synthesized in the plastids of plant cells. These pigments primarily absorb  the blue wavelengths, allowing the longer wavelengths to be scattered and producing the yellow colour.

RuDP stands for Ribulose Diphosphate (also called RuBP - Ribulose-1,5-bisphosphate), the 5-carbon molecule that accepts CO2 in the Calvin cycle's first step, catalyzed by the enzyme RuBisCO.

Photolysis is the light-driven decomposition of water into hydrogen and oxygen, occurring during photosynthesis' light-dependent reactions. Chlorophyll absorbs light energy to split water molecules, releasing electrons for the electron transport chain and oxygen as a byproduct.

The light-independent reactions, also known as the Calvin cycle, occur in the stroma of the chloroplast. The stroma is the fluid-filled space surrounding the thylakoids where CO2 fixation and sugar synthesis take place. Light-dependent reactions occur in the thylakoid membranes.

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The total amount of energy that plants assimilate by photosynthesis is called gross primary production.

During photosynthesis process, solar energy is being transferred through the food chain. It is being transformed from one chemical form to another. In this process, much of the food energy is lost as metabolic heat.

Only about 1-2% of the water absorbed by plant roots is actually used in photosynthesis to produce carbohydrates. The remaining 98-99% is lost through transpiration. This water loss is necessary to create the transpiration pull that drives water and mineral absorption from soil, making it essential despite the inefficiency.