Photosynthesis In Higher Plants

In photosynthesis, the chloroplast's membrane system captures light energy, which is then used to synthesize ATP and NADPH. These processes are known as light reactions or photochemical reactions, as they are directly driven by light.

At lower light intensities, there exists a linear relationship between incident light and photosynthetic fixation) rate. At higher light intensities, the rate becomes stable as other factors become limiting.

Option A: It provides precursor for the synthesis of stress hormone in plants.Carotenoids are precursors for the synthesis of abscisic acid (ABA), which is a crucial plant hormone involved in stress responses like drought and cold tolerance. Specifically, violaxanthin (a type of xanthophyll, which is a carotenoid derivative) is cleaved to form xanthoxin, a precursor to ABA.This statement isTRUE.Option B: It protects chlorophyll from photo-oxidation.Carotenoids play a vital role in photoprotection. They absorb excess light energy and dissipate it as heat, preventing the formation of reactive oxygen species (ROS) that can damage chlorophyll and other photosynthetic components, a process known as photo-oxidation.This statement isTRUE.Option C: It is an accessory pigment which absorbs light at .Carotenoids are indeed accessory pigments. However, their primary absorption spectrum is typically in the blue-violet region, usually between 400 nm and 550 nm. They appear yellow, orange, or red because they absorb blue and green light and reflect these colors. The 600-700 nm range is predominantly where chlorophylls (especially chlorophyllaandb) absorb red light strongly.Therefore, this statement isFALSE.Option D: It accumulates in chromoplasts during fruit ripening.Chromoplasts are types of plastids that synthesize and store pigments, particularly carotenoids. During fruit ripening, chlorophyll often degrades, and carotenoids are synthesized and accumulate in chromoplasts, leading to the characteristic yellow, orange, or red colors of many mature fruits.This statement isTRUE.The only false statement is Option C.The final answer is