Question

question 3 (1 point)
which statements about feedback systems are correct?
i. a negative feedback system tends to increase the stimulus that causes the
effect.
ii. a positive feedback loop, involving the kidney, maintains blood glucose
homeostasis.
iii. a positive feedback system would be unable to maintain homeostasis, since it
would be unable to maintain any type of equilibrium.
iv. an example of how the body uses a positive feedback system to maintain body
temperature is the release of water onto the surface of the skin.
v. a feedback system requires co-ordination between the sensory receptors, an
integrator centre, and an effector.
i, ii, and iii
ii and iv only
iii only
i, iii, and v
iii and v only

Explanation:

• Statement I: A negative feedback system reduces the stimulus, not increases it. So, this statement is incorrect.
• Statement II: The kidney - related feedback for blood glucose is a negative feedback (e.g., regulation of blood glucose by the kidneys in some aspects). Positive feedback loops are not the main way kidneys maintain blood glucose homeostasis. So, this statement is incorrect.
• Statement III: Positive feedback systems amplify a change and are not designed to maintain homeostasis (which is about maintaining a stable internal environment). So, this statement is correct.
• Statement IV: The release of water onto the skin (sweating) is a negative feedback mechanism for temperature regulation. So, this statement is incorrect.
• Statement V: A feedback system (both positive and negative) requires sensory receptors (to detect a change), an integrator centre (to process information), and an effector (to carry out a response). So, this statement is correct.

Answer:

III and V only