Browse exam-wise, subject-wise, and country-wise MCQs with explanations.
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Endocrine effects often develop more slowly and last longer than nerve impulses because hormones circulate and alter metabolic or gene-regulatory processes.
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Hormone action requires receptor binding. If receptor structure is altered, the target cell may fail to respond even when the hormone is present.
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Nematodes use signaling pathways to regulate development, molting, reproduction, and stress responses. Chemical communication is not limited to vertebrates.
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Invertebrates often use neurosecretory cells and endocrine-like messengers to regulate reproduction, growth, and behavior, even without vertebrate-type glands.
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Some crustaceans use neuroendocrine hormones to move pigments within chromatophores, changing body coloration for camouflage or signaling.
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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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Ecdysone is an arthropod molting hormone. It initiates cuticle shedding and developmental transitions when balanced with juvenile hormone.
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Calcitonin from the thyroid helps reduce blood calcium, especially by influencing bone calcium deposition. Its role opposes parathyroid hormone.
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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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Negative feedback reduces the original change. When blood glucose falls, insulin secretion declines, preventing excessive lowering of glucose.
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Glucocorticoids such as cortisol support prolonged stress responses by mobilizing energy and modifying immune activity. They act more slowly than adrenaline.
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Adrenaline from the adrenal medulla prepares the body for emergency action by increasing heart rate, airway dilation, and energy mobilization.
