Botany MCQs for NEET — Practice Questions with Answers

In C4 plants, carboxylation occurs in two steps. First, PEP (phosphoenolpyruvate) combines with CO2 to form oxaloacetic acid, which is then converted to malate. The malate is transported to bundle-sheath cells, where it releases CO2 to be fixed again by RuBP (ribulose bisphosphate) in the Calvin cycle.

Spirogyra is a filamentous green algae that contains ribbon-shaped chloroplasts arranged in a spiral manner. This unique structure is why Spirogyra is known for its distinctive chloroplast morphology.

Diatoms are a major group of algae and are among the most common types of phytoplankton. They are photoautotrophs, meaning they can produce their own food through photosynthesis using light energy.

Photosynthesis can occur in visible light obtained from any source, not just sunlight. This means that artificial light sources that emit visible light can also drive the photosynthetic process.

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.