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Communication and homeostasis

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Question 3

Which of the following statements correctly describes a communication or homeostatic control mechanism in multicellular organisms?

A

When blood water potential decreases, osmoreceptors in the pituitary gland shrink, stimulating the direct secretion of antidiuretic hormone (ADH) to decrease the permeability of the collecting duct to water.

B

In blood glucose regulation, the peptide hormone insulin binds to specific cell-surface receptors, triggering an intracellular signaling cascade that causes vesicles containing GLUT4 transporter proteins to fuse with the cell-surface membrane.

C

In thermoregulation, the hypothalamus acts as both the primary receptor and the sole effector, directly decreasing the metabolic rate of hepatocytes to generate heat when core temperature falls below the set point.

D

The initial depolarization stage of an action potential in a sensory neurone is controlled by negative feedback, as the influx of Na+\text{Na}^+Na+ ions causes the membrane potential to become less negative, which directly closes voltage-gated sodium channels.

Markscheme

Communication and homeostasis Questions

  1. A Level
  2. /Biology
  3. /Communication and homeostasis

19 exam-style questions on OCR A A Level Biology Communication and homeostasis. Each one has a worked solution and a mark scheme showing where the marks go.

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