Botany MCQs for NEET — Practice Questions with Answers

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.

In cyclic photophosphorylation, the same chlorophyll molecule acts as both the donor and acceptor of electrons. This process occurs in the thylakoid membrane of the chloroplast and is used to produce ATP without the production of NADPH or oxygen.

C₄ plants are adapted to efficiently perform photosynthesis even in low CO₂ concentrations. They have a specialized mechanism that concentrates CO₂ in the bundle sheath cells, minimizing photorespiration and allowing the plant to thrive in conditions where CO₂ is limited.

In C4 plants, the bundle sheath cells contain large chloroplasts that lack grana, hence they are agranal. This adaptation is crucial for the efficient functioning of the C4 pathway, where the Calvin cycle takes place in the bundle sheath cells.

Lateral meristems, such as the cambium, are involved in the secondary growth of plants, which increases the thickness of stems and roots. The cambium is responsible for producing new layers of vascular tissue, including both xylem and phloem.

Hydathodes are specialized structures found in the epidermal tissue system of leaves. They are involved in the process of guttation, where water is exuded from the tips or edges of leaves. This is different from transpiration, which occurs through stomata.