NEET Practice Questions (MCQs) with Answers & Solutions

The reduction of ADP to ATP in photosynthesis occurs through a process known as chemiosmosis, which involves a high concentration of H+ ions (protons) across the thylakoid membrane. This proton gradient drives ATP synthesis as protons flow back across the membrane through ATP synthase.

The process of ATP formation from ADP in the presence of light in chloroplasts is called photophosphorylation. This process uses the energy from light to add a phosphate group to ADP, forming ATP, and it occurs in the thylakoid membranes of chloroplasts during the light reactions of photosynthesis.

Both aldolase and triose phosphate isomerase are enzymes involved in the Calvin cycle of C₃ plants and in the Embden-Meyerhof-Parnas (EMP) pathway, which is another name for glycolysis. Aldolase splits fructose-1,6-bisphosphate into two three-carbon sugars, while triose phosphate isomerase interconverts dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.

O₂ (oxygen) is the by-product of photosynthesis. During the light-dependent reactions of photosynthesis, water molecules are split (photolysis) to release oxygen, electrons, and protons. The oxygen is then released as a by-product.

The reduction of carbon occurs in the stroma of the chloroplast. This is where the Calvin cycle takes place, utilizing ATP and NADPH produced in the light-dependent reactions to fix carbon dioxide into organic molecules.

Cyclic photophosphorylation occurs mostly in stroma lamellae membrane and in this process, only ATP is released.

The fixation and reduction of CO₂ in the Calvin cycle (also known as the dark reaction) occur in the presence of ATP and NADPH, which are generated during the light reactions of photosynthesis. ATP provides the necessary energy, while NADPH provides the reducing power for the conversion of CO₂ into glucose.

In plants, sugar is transported through the phloem vessels primarily in the form of sucrose. Sucrose is a disaccharide composed of glucose and fructose. It is the main form of sugar transported because it is more stable and less reactive than glucose.

Photolysis of water in photosynthesis involves the splitting of water molecules into oxygen, protons, and electrons. This process is catalyzed by the oxygen-evolving complex (OEC) of photosystem II, which requires manganese (Mn++) and chloride (Cl-) ions to function properly.