Consider the following statements about DNA replication: 1. It is semiconservative. 2. It requires DNA polymerase. 3. It occurs in the cytoplasm of eukaryotic cells. Which of the above is/are correct? MCQ with Answer and Explanation
Consider the following statements about DNA replication:
1. It is semiconservative.
2. It requires DNA polymerase.
3. It occurs in the cytoplasm of eukaryotic cells.
Which of the above is/are correct?
A. 1 and 2 only
B. 2 and 3 only
C. 1, 2, and 3
D. 1 and 3 only
Answer: Option A
Solution (By JKSSB Mock Tests)
DNA replication is semiconservative and uses DNA polymerase. In eukaryotes, it occurs in the nucleus, not cytoplasm. So statement 3 is incorrect.
Consider statements about microorganisms: 1. Cyanobacteria are photosynthetic prokaryotes. 2. Mycorrhiza is a symbiotic association between fungi and plant roots. 3. Nitrosomonas is a denitrifying bacterium. Which are correct?
Explanation:
Cyanobacteria (blue-green algae) are photosynthetic, oxygenic prokaryotes that play a crucial role in nitrogen fixation in aquatic and terrestrial ecosystems. Mycorrhiza is a mutualistic symbiotic association between a fungus and the roots of a vascular plant, where the fungus aids in nutrient absorption and the plant provides carbohydrates. Nitrosomonas is a nitrifying bacterium that converts ammonia to nitrite; denitrifying bacteria like Pseudomonas convert nitrates to nitrogen gas. Thus, statements 1 and 2 are correct.
Explanation:
ATP synthase (CF₀-CF₁ complex) uses the proton gradient across the thylakoid membrane to synthesize ATP. Rubisco fixes CO₂, NADP reductase reduces NADP⁺, PEP carboxylase is in C4 plants.
Explanation:
Ethylene is a gaseous hormone that accelerates ripening, promotes leaf and fruit abscission, and senescence. Auxin and cytokinin promote growth, gibberellin elongation. Ethylene is used commercially for fruit ripening.
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