Category: Daily Practice MCQs
Agriculture Daily Practice MCQs – 73
By Agritests |
27 Jul, 2026
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1. Which component of the oxygen-evolving complex (OEC) of Photosystem II is directly responsible for splitting water molecules? A. Magnesium porphyrin complex B. Manganese-calcium (Mn₄CaO₅) cluster C. Ferredoxin D. Cytochrome b6f complex Show Answer Answer: B. Manganese-calcium (Mn₄CaO₅) cluster Explanation: The Mn₄CaO₅ cluster of the oxygen-evolving complex oxidizes water, releasing electrons, protons, and molecular oxygen […]
Agriculture Daily Practice MCQs – 72
By Agritests |
27 Jul, 2026
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1. The enzyme ferredoxin–NADP+ reductase (FNR) catalyzes the formation of: A. ATP from ADP B. NADPH from NADP+ C. Oxygen from water D. Glucose from glyceraldehyde-3-phosphate Show Answer Answer: B. NADPH from NADP+ Explanation: Ferredoxin–NADP+ reductase transfers electrons from ferredoxin to NADP+, producing NADPH required for the Calvin cycle. 2. Which exchangeable cation generally dominates […]
Agriculture Daily Practice MCQs – 71
By Agritests |
27 Jul, 2026
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1. Which enzyme catalyzes the conversion of atmospheric nitrogen (N₂) to ammonia (NH₃) and is irreversibly inhibited by oxygen? A. Nitrate reductase B. Nitrite reductase C. Nitrogenase D. Glutamate dehydrogenase Show Answer Answer: C. Nitrogenase Explanation: Nitrogenase catalyzes biological nitrogen fixation and is highly sensitive to oxygen, requiring protective mechanisms such as leghemoglobin in root […]
Agriculture Daily Practice MCQs – 70
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27 Jul, 2026
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1. Which enzyme catalyzes the oxygenation reaction of RuBP during photorespiration? A. Phosphoenolpyruvate carboxylase B. Rubisco C. Carbonic anhydrase D. Ribulose phosphate epimerase Show Answer Answer: B. Rubisco Explanation: Rubisco possesses both carboxylase and oxygenase activities. Under low CO₂ and high O₂ conditions, it oxygenates RuBP, initiating photorespiration. 2. Which of the following soil phosphorus […]
Agriculture Daily Practice MCQs – 69
By Agritests |
27 Jul, 2026
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1. In the Z-scheme of photosynthesis, the final electron acceptor of Photosystem I is: A. Plastoquinone B. Plastocyanin C. Ferredoxin D. Cytochrome b6f complex Show Answer Answer: C. Ferredoxin Explanation: Electrons from Photosystem I are transferred to ferredoxin, which ultimately reduces NADP⁺ to NADPH via ferredoxin-NADP reductase. 2. Which soil order is typically associated with […]
Agriculture Daily Practice MCQs – 68
By Agritests |
27 Jul, 2026
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1. In the Hatch-Slack pathway of C₄ photosynthesis, the first stable product formed after CO₂ fixation is: A. 3-Phosphoglycerate (3-PGA) B. Oxaloacetic acid (OAA) C. Ribulose-1,5-bisphosphate (RuBP) D. Malonic acid Show Answer Answer: B. Oxaloacetic acid (OAA) Explanation: In C₄ plants, PEP carboxylase fixes CO₂ into oxaloacetic acid (OAA), the first stable four-carbon compound. 2. […]
Agriculture Daily Practice MCQs – 67
By Agritests |
27 Jul, 2026
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1. In plants, the enzyme glutamine synthetase primarily catalyzes the: A. Reduction of nitrate to nitrite B. Conversion of glutamine to glutamate C. Assimilation of ammonia into glutamine D. Oxidation of ammonium to nitrate Show Answer Answer: C. Assimilation of ammonia into glutamine Explanation: Glutamine synthetase incorporates ammonium into glutamate to form glutamine, the first […]
Agriculture Daily Practice MCQs – 66
By Agritests |
27 Jul, 2026
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1. Which enzyme is responsible for the biological fixation of atmospheric nitrogen by catalyzing the reduction of N₂ to NH₃? A. Nitrate reductase B. Nitrite reductase C. Nitrogenase D. Glutamate synthase Show Answer Answer: C. Nitrogenase Explanation: Nitrogenase is the ATP-dependent enzyme complex that converts atmospheric nitrogen into ammonia under anaerobic conditions. 2. The principal […]
Agriculture Daily Practice MCQs – 65
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27 Jul, 2026
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1. In photorespiration, the conversion of glycolate to glycine primarily occurs in the: A. Chloroplast B. Peroxisome C. Mitochondrion D. Vacuole Show Answer Answer: B. Peroxisome Explanation: During photorespiration, glycolate produced in the chloroplast is transported to the peroxisome, where it is oxidized to glyoxylate and then converted into glycine. 2. Which soil order is […]
Agriculture Daily Practice MCQs – 64
By Agritests |
27 Jul, 2026
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1. In the Calvin cycle, the enzyme that catalyzes the regeneration of ribulose-1,5-bisphosphate (RuBP) from ribulose-5-phosphate is: A. Rubisco B. Phosphoribulokinase C. Aldolase D. Transketolase Show Answer Answer: B. Phosphoribulokinase Explanation: Phosphoribulokinase catalyzes the ATP-dependent phosphorylation of ribulose-5-phosphate to regenerate RuBP. 2. Which soil colloid contributes the greatest proportion of pH-dependent negative charge? A. Kaolinite […]