Photosynthesis in Higher Plants: Class 11 Biology Q&A · Page 2
28 free answers on Photosynthesis in Higher Plants (Biology) for Class 11 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- BiologyClass 11All
Who gave the law of limiting factors?
F.F. Blackman proposed the Law of Limiting Factors in 1905. The law states: "When a physiological process depends on multiple factors, its rate is limited by the factor present in minimal or near-minimal quantity, and increasing only that factor will enhance the process rate." Application to photosynthesis: At low light, increasing light intensity boosts photosy
- BiologyClass 11All
Give the chemical equation of photosynthesis.
Overall photosynthesis equation: 6CO₂ + 12H₂O --[Light/Chlorophyll]--> C₆H₁₂O₆ + 6O₂ + 6H₂O Key points: Requires 6 molecules of CO₂ and 12 molecules of water Produces 1 glucose molecule, 6 O₂ molecules, and 6 H₂O molecules The oxygen released comes from water photolysis, not CO₂ (proven by isotope studies)
- BiologyClass 11All
What is the first stable product of C4 cycle?
The first stable product of the C4 pathway is oxaloacetic acid (OAA), a 4-carbon dicarboxylic acid. It forms when PEP carboxylase (PEPcase) catalyzes CO₂ fixation to phosphoenolpyruvate (PEP) in mesophyll cells.
- BiologyClass 11All
Name two photosynthetic pigments belonging to carotenoids.
The two major carotenoid pigments are: Carotene (β-carotene) – orange pigment, C₄₀H₅₆, precursor of vitamin A Xanthophyll (lutein, zeaxanthin) – yellow pigments containing oxygen Functions: Absorb blue-green light (450-550 nm) Protect chlorophyll from photo-oxidative damage Transfer energy to chlorophyll a
- BiologyClass 11All
Name the technique used to separate leaf pigments.
Paper chromatography (or thin-layer chromatography) separates photosynthetic pigments based on their differential solubility in organic solvents and adsorption rates on paper/silica gel. Typical Rf values (in petroleum ether:acetone): Carotene: 0.95 (highest, most non-polar) Chlorophyll a: 0.65 Chlorophyll b: 0.45 Xanthophylls: 0.35 (lowest, most polar)</li
- BiologyClass 11All
What is photorespiration?
Photorespiration is the light-dependent uptake of O₂ and release of CO₂ that occurs when RuBisCO's oxygenase activity dominates over carboxylase activity. This wasteful process: Occurs primarily in C3 plants Results in 25% loss of fixed carbon Involves three organelles: chloroplasts, peroxisomes, and mitochondria Does not produce ATP or NADPH Increases wi
- BiologyClass 11All
Expand RuBisCO.
RuBisCO stands for Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase. This bifunctional enzyme is the most abundant protein on Earth and catalyzes: Carboxylation: CO₂ fixation to RuBP (photosynthesis) Oxygenation: O₂ binding to RuBP (photorespiration)
- BiologyClass 11All
Define photophosphorylation.
Photophosphorylation is the light-dependent synthesis of ATP from ADP and inorganic phosphate (Pi) in the chloroplast thylakoid membranes. This process occurs via chemiosmosis, where light energy creates a proton gradient that drives ATP synthase enzyme activity. Two types exist: Non-cyclic photophosphorylation (produces ATP + NADPH + O₂) Cyclic photop