Practice BS Zoology Semester Exam questions with answers and explanations.
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Dendrites increase the receptive surface of a neuron. Multiple dendrites allow integration of inputs from several neurons or 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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Invertebrates often use neurosecretory cells and endocrine-like messengers to regulate reproduction, growth, and behavior, even without vertebrate-type glands.
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Hearing depends on mechanical vibrations that stimulate hair cells or related mechanoreceptors. These receptors convert sound waves into neural signals.
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Sensory adaptation is reduced responsiveness during continuous stimulation. It allows animals to remain sensitive to new or changing stimuli.
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Nodes of Ranvier are gaps in myelin where ion exchange occurs. Saltatory conduction between nodes increases impulse speed.
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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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Nematodes use signaling pathways to regulate development, molting, reproduction, and stress responses. Chemical communication is not limited to vertebrates.
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Olfactory receptors are chemoreceptors that detect airborne molecules. They help animals locate food, mates, predators, and environmental signals.
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The inner ear contains balance organs that detect head movement and position. Damage can disrupt equilibrium and coordination.
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Cephalopods have large brains and advanced sensory systems for invertebrates. Their behavior includes learning, camouflage, and complex movement control.
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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.
