Browse exam-wise, subject-wise, and country-wise MCQs with explanations.
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Muscular systems are not required in unicellular or very small organisms. Protozoans and many cells move by cilia, flagella, pseudopodia, or cytoplasmic streaming.
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In a withdrawal reflex, receptors detect heat or pain, neurons carry signals, and skeletal muscles act as effectors to move the limb away.
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Keratin is a tough structural protein in hair, nails, claws, and epidermis. It strengthens integumentary derivatives and improves protection.
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Amoeba extends pseudopodia through changes in cytoplasm. This movement also helps engulf food by phagocytosis.
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Cilia generate movement at the cellular level, while muscles act as tissues and organs. Both contribute to locomotion or movement of materials.
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Mechanoreceptors detect mechanical forces such as pressure, touch, vibration, stretch, or sound. They convert mechanical stimuli into nerve impulses.
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Paramecium uses coordinated ciliary beating for swimming and feeding currents. It lacks muscles and a skeleton, so movement is cellular rather than organ-system based.
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Amphibian skin is moist and permeable, allowing water loss in dry conditions. This makes humid habitats important for many amphibians.
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Chitin, scales, and feathers are different body coverings, but all contribute to protection. Some also support movement, insulation, or display depending on the animal.
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Feathers are important for insulation and flight surface. Losing many feathers can reduce thermal control or flight performance until new feathers develop.
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Chemoreceptors respond to chemical molecules in air, water, or body fluids. Smell and taste are common chemosensory functions.
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A flagellum produces wave-like motion that propels a sperm cell. It is a cellular movement mechanism, not a skeletal or circulatory adaptation.
