The enzyme that unwinds the DNA double helix during replication is:
A. Topoisomerase
B. Ligase
C. DNA polymerase
D. Helicase
Answer: Option D
Solution (By JKSSB Mock Tests)
Helicase uses ATP to separate the hydrogen-bonded base pairs, creating the replication fork. Topoisomerase relieves supercoiling ahead of the fork. DNA polymerase synthesizes new DNA, ligase joins fragments. Helicase is essential for strand separation and replication initiation.
Explanation:
Spectrophotometry measures the absorbance of light by a solution at a specific wavelength, which is proportional to the concentration of the absorbing substance (Beer-Lambert law).
Consider the following statements regarding photosynthesis:
1. Light reactions occur in the thylakoid membranes.
2. Oxygen is released from carbon dioxide.
3. ATP and NADPH are produced in the light reactions.
Which of the above is/are correct?
Explanation:
Light reactions occur in thylakoid membranes, producing ATP, NADPH, and oxygen. Oxygen comes from water (photolysis), not CO₂. So statement 2 is incorrect. 1 and 3 are correct.
Explanation:
Diapedesis (extravasation) is the migration of leukocytes through the endothelial junctions of capillaries into tissues in response to inflammation. Chemotaxis is the directed movement along a chemical gradient, phagocytosis is ingestion, opsonization is coating for phagocytosis. Both diapedesis and chemotaxis are part of the inflammatory response.
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