Browse exam-wise, subject-wise, and country-wise MCQs with explanations.
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Physical and chemical barriers are innate defenses. They act broadly and immediately against many pathogens before specific immune responses develop.
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Ecdysone triggers molting, while juvenile hormone determines the character of the molt. High juvenile hormone favors larval traits.
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Animal development often depends on hormonal signals integrated with environmental cues. In invertebrates, molting and metamorphosis are classic examples.
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In open circulatory systems, hemolymph leaves vessels and bathes tissues in body cavities. Arthropods and many molluscs show this arrangement.
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Fever is a systemic innate response that can slow pathogen growth and enhance immune activity. It is not antigen-specific.
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Target tissues respond only when they have the appropriate receptor and signaling machinery. Circulation alone does not guarantee a response.
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Hormone action depends partly on how long the hormone remains active in circulation. Rapid degradation shortens the response.
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Closed circulatory systems keep blood within vessels, allowing more controlled pressure and distribution. Annelids such as earthworms are classic examples.
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Inflammation increases local blood flow and vascular permeability, bringing immune cells and defensive proteins to injury or infection sites.
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Many invertebrates use neurosecretory cells, blending nervous and endocrine functions. These cells release chemicals that regulate growth, reproduction, and behavior.
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Sponges do not possess true organs or endocrine glands, but cells can communicate chemically to coordinate basic activities.
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Hemolymph is the circulating fluid of many invertebrates with open circulatory systems, especially arthropods. It may transport nutrients, wastes, hormones, and immune cells.
