The disease caused by the poliovirus primarily affects the:
A. Lungs
B. Nervous system
C. Liver
D. Kidney
Answer: Option B
Solution (By JKSSB Mock Tests)
Poliovirus attacks motor neurons in the spinal cord and brainstem, causing paralysis. It spreads via the fecal-oral route. Vaccination (IPV/OPV) has almost eradicated it globally. The virus replicates in the intestine and then invades the nervous system. Polio survivors may suffer post-polio syndrome later.
Explanation:
Accommodation involves lens shape change via ciliary muscles. The blind spot lacks photoreceptors; fovea has high cone density; pupil adjusts via iris.
Explanation:
Secondary consumers are carnivores or omnivores that eat primary consumers (herbivores). Example: frog eating grasshopper. Producers are autotrophs, primary consumers are herbivores, decomposers break down dead matter. Trophic levels represent energy transfer steps. Energy decreases at each higher level.
Explanation:
Earthworms (annelids) have a closed circulatory system with blood contained within vessels. Cockroach, snail, and butterfly have open circulatory systems where hemolymph bathes organs directly.
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