NEET Practice Questions (MCQs) with Answers & Solutions

Chlorophyll-a and chlorophyll-b are two types of chlorophyll found in plants and algae. Chlorophyll-a has a methyl group (-CH3) at the third carbon position in its structure, whereas chlorophyll-b has an aldehyde group (-CHO) at the same position. This difference in functional groups distinguishes chlorophyll-a from chlorophyll-b.

In non-cyclic photophosphorylation, light energy is used to produce ATP and NADPH. This process involves both photosystem I (PS-I) and photosystem II (PS-II). The electron flow is unidirectional, starting from water and ending at NADP+ to form NADPH. Therefore, all the given statements are correct.

In non-cyclic photophosphorylation, the electrons lost by P680 in photosystem II are replaced by electrons obtained from the splitting of water molecules (photolysis). This process releases oxygen and provides electrons to replenish the electron deficit in P680.

Algae in the oceans are responsible for a significant portion of global photosynthesis. They contribute to about 85-90% of the world's photosynthesis due to their vast numbers and widespread presence in the marine environment.

The primary processes of photosynthesis, which involve light reactions, take place in the grana. The secondary processes, which include the Calvin cycle (dark reactions), occur in the stroma.

For the synthesis of one molecule of glucose during photosynthesis, 18 molecules of ATP and 12 molecules of NADPH are required. This is because six turns of the Calvin cycle are needed to produce one glucose molecule, and each turn uses 3 ATP and 2 NADPH.

Magnesium (Mg) is an essential element for the biosynthesis of chlorophyll. It is a central atom in the chlorophyll molecule and plays a crucial role in the absorption of light during photosynthesis. Without magnesium, plants cannot produce chlorophyll, which leads to a condition known as chlorosis.

An action spectrum is a graph that shows the rate of photosynthesis at different wavelengths of light. It indicates which wavelengths are most effectively used in the process of photosynthesis. This is different from an absorption spectrum, which shows the absorption of light by pigments.

Xanthophylls are oxygenated derivatives of carotenes and have the molecular formula C₄₀H₅₆O₂. They are pigments found in plants and contribute to the yellow and orange colors in leaves.