Practice Pakistan questions with answers and explanations.
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The central nervous system receives and integrates sensory signals, then coordinates behavior and physiological responses through motor pathways.
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Chemical senses work when molecules interact with receptor proteins. Taste usually detects dissolved chemicals, while smell detects airborne molecules that dissolve in mucus.
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Stretch receptors detect mechanical deformation of tissues. In internal organs, they provide feedback about distension and physiological state.
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Ecdysone is an arthropod molting hormone. It initiates cuticle shedding and developmental transitions when balanced with juvenile hormone.
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The lateral line detects water displacement, allowing fishes to respond quickly to pressure waves from predators, prey, or obstacles.
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Touch receptors respond to mechanical deformation of skin. They are mechanoreceptors specialized for pressure or vibration rather than light.
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Multicellular animals require communication to coordinate movement, feeding, defense, reproduction, and internal stability across specialized tissues.
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Juvenile hormone helps maintain larval features. Declining juvenile hormone allows metamorphic progression toward pupal or adult stages.
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In aquatic environments, vibrations and water movements can reveal prey even in darkness. A lateral line is specialized for this mechanosensory task.
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Sensory organs detect stimuli, but the nervous system transmits and processes those signals to produce perception or response.
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Insulin promotes glucose uptake and storage, reducing blood glucose after meals. It is secreted by pancreatic beta cells and acts through target-cell receptors.
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Some crustaceans use neuroendocrine hormones to move pigments within chromatophores, changing body coloration for camouflage or signaling.
