The element that is the central atom in chlorophyll is:
A. Iron
B. Calcium
C. Cobalt
D. Magnesium
Answer: Option D
Solution (By JKSSB Mock Tests)
Magnesium is the central atom in the porphyrin ring of chlorophyll, essential for light absorption in photosynthesis. Iron is in heme, calcium structural, cobalt in vitamin B₁₂.
Explanation:
Niacin is part of NAD⁺/NADH, which donates electrons to the electron transport chain to generate the proton gradient for ATP synthesis. All B vitamins contribute indirectly.
Explanation:
Veins, especially in limbs, have one-way valves that prevent the backflow of blood as it returns to the heart against gravity. Arteries have thick walls to withstand pressure and lack valves. Capillaries have no valves.
Explanation:
The term 'biology' was independently coined by Jean-Baptiste Lamarck (France) and Gottfried Reinhold Treviranus (Germany) around 1802. Aristotle is father of biology, Linnaeus taxonomy, Darwin evolution.
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