The pigment that protects skin from UV radiation is:
A. Keratin
B. Elastin
C. Collagen
D. Melanin
Answer: Option D
Solution (By JKSSB Mock Tests)
Melanin, produced by melanocytes, absorbs and dissipates UV radiation, protecting skin cells from DNA damage. Keratin is structural protein, collagen provides strength, elastin elasticity. Increased melanin production causes tanning.
Explanation:
Norman Myers introduced the concept of biodiversity hotspots in 1988—regions with high endemic species and significant habitat loss (≥70% original vegetation lost). Examples: Western Ghats, Indo-Burma. Conservation efforts prioritize these areas. Darwin contributed evolution, Humboldt to biogeography, E.O. Wilson is known for sociobiology and biodiversity studies. Hotspots cover only 2.4% of Earth's land but hold >50% of plant species.
Explanation:
The aorta is the main and largest artery originating from the left ventricle, distributing oxygenated blood to all parts of the body through its branches. The pulmonary artery carries deoxygenated blood to lungs. Coronary arteries supply the heart muscle, carotid arteries supply the brain. The aorta has a diameter of about 2-3 cm in adults.
Explanation:
Growth in living organisms occurs from inside the body through cell division and synthesis of new cellular material. In contrast, non-living things grow by the accumulation of material on their surface externally. Living growth is intrinsic and irreversible, whereas non-living growth is extrinsic and can be reversed.
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