Practice Pakistan questions with answers and explanations.
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At many neuromuscular junctions, acetylcholine transmits the signal from motor neuron to muscle. Blocking its receptors prevents normal contraction.
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Nociceptors detect potentially damaging stimuli and generate pain signals. They protect the body by prompting avoidance of injury.
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The neuron cell body contains the nucleus and organelles needed for protein synthesis and cell maintenance. It integrates many incoming signals.
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Negative feedback reduces the original change. When blood glucose falls, insulin secretion declines, preventing excessive lowering of glucose.
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Cnidarians have diffuse nerve nets rather than highly centralized brains. This arrangement coordinates simple movements and responses in radially symmetrical bodies.
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Echolocation uses sound production and hearing. Reflected sound waves are detected by auditory mechanoreceptors and interpreted by the nervous system.
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The nervous system can control glandular secretion through autonomic pathways. Glands act as effectors responding to neural signals.
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Parathyroid hormone raises blood calcium through effects on bone, kidneys, and vitamin D activation. It is regulated by negative feedback.
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Annelids have a more centralized nervous system with ganglia and nerve cords. This supports coordinated segmental movement and sensory responses.
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The lateral line is used for sensing water movement and vibration. Damage impairs orientation, schooling, prey detection, and predator avoidance.
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Olfactory receptors detect odor molecules. If access to receptors is blocked, smell perception decreases even if the nervous system remains intact.
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Calcitonin from the thyroid helps reduce blood calcium, especially by influencing bone calcium deposition. Its role opposes parathyroid hormone.
