Browse exam-wise, subject-wise, and country-wise MCQs with explanations.
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Thyroid hormones are essential for amphibian metamorphosis and vertebrate development. Deficiency can delay or prevent normal transformation.
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The thyroid produces thyroxine, which influences metabolic rate, growth, and development. Low thyroxine commonly slows metabolism.
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Steroid hormones are lipid-soluble and can pass through cell membranes. Their receptor complexes often regulate transcription in the nucleus.
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Peptide hormones are water-soluble and usually bind surface receptors, triggering intracellular signaling. Steroid hormones often cross membranes and bind intracellular receptors.
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Endocrine glands are ductless and release hormones into blood or body fluid. Exocrine glands release secretions through ducts onto surfaces or into cavities.
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Hormones affect only target cells that possess matching receptors. Receptor specificity explains why a circulating hormone does not act equally on every tissue.
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Endocrine glands release hormones into blood or body fluids. These chemical messengers reach target cells with specific receptors.
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Glucagon is secreted by pancreatic alpha cells and stimulates glycogen breakdown and glucose release, helping maintain blood glucose during fasting.
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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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Multicellular animals require communication to coordinate movement, feeding, defense, reproduction, and internal stability across specialized tissues.
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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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Olfactory receptors detect odor molecules. If access to receptors is blocked, smell perception decreases even if the nervous system remains intact.
