Limiting Factors in Photosynthesis — NEET Biology
📚 Practice ConceptBased on the graph, answer the following questions: (a) At which point/s (A, B or C) in the curve light is a limiting factor? (b) What could be the limiting factor/s in region A? (c) What do C and D represent on the curve?
Which of the following statements about the requirements and associated components of photosynthesis are correct? S1: Chlorophyll 'a' is the chief pigment directly involved in trapping light energy for photosynthesis, while accessory pigments broaden the absorption spectrum. S2: Water serves as the electron donor in oxygenic photosynthesis and is the source of all oxygen released. S3: Carbon dioxide is fixed in the stroma to synthesize sugars, utilizing the energy from ATP and NADPH produced in the light reaction. S4: Mitochondria are indispensable cellular organelles where the light-dependent reactions of photosynthesis primarily occur. S5: Optimal light intensity for photosynthesis is always full sunlight, as higher intensities never lead to chlorophyll degradation.
View solution & NCERT explanation
Correct answer: A — S1, S2 and S3 are correct
The question focuses on the essential requirements and components for photosynthesis as described in NCERT. S1: This statement is correct. "Chlorophyll a is the chief pigment associated with photosynthesis. Though chlorophyll is the major pigment responsible for trapping light, other thylakoid pigments like chlorophyll b, xanthophylls and carotenoids, which are called accessory pigments, also absorb light and transfer the energy to chlorophyll a." They enable a wider range of wavelengths to be utilized. S2: This statement is correct. "In green plants H2O is the hydrogen donor and is oxidised to O2." and "The electrons that were moved from photosystem II must be replaced. This is achieved by electrons available due to splitting of water." This process also releases oxygen. S3: This statement is correct. "In stroma, enzymatic reactions synthesise sugar, which in turn forms starch." and "The products of light reaction are ATP, NADPH and O2... ATP and NADPH are used to drive the processes leading to the synthesis of food, more accurately, sugars." S4: This statement is NOT correct. The light-dependent reactions of photosynthesis occur in the thylakoid membranes within chloroplasts, not in mitochondria. Mitochondria are involved in cellular respiration. S5: This statement is NOT correct. "What is interesting to note is that light saturation occurs at 10 per cent of the full sunlight. Hence, except for plants in shade or in dense forests, light is rarely a limiting factor in nature. Increase in incident light beyond a point causes the breakdown of chlorophyll and a decrease in photosynthesis." Therefore, S1, S2, and S3 are correct.
What does NCERT say about Based on graph answer?
Has this concept appeared in NEET?
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Through deep analysis of NEET and NTA, 176 of the 180 ReNEET 2026 (June 21) questions were already in the MedicNEET question bank before the exam.
176/180MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.