Lab: Blood Typing — Unit test

Question 2 • Biology - SC3209 IC

Which of the following describes a positive feedback loop?

Answer

When blood sugar is low, the body sends hormones that increase blood sugar.

When the body senses that the heart rate is very high, it secretes hormones that decrease the heart rate.

When someone is exercising intensely, the body sends hormones that increase oxygen supply for cellular respiration.

When a pregnant woman begins to go into labor, the body sends hormones that increase the intensity of the labor contractions.

Explanation

A positive feedback loop amplifies an initial change rather than counteracting it. During labor, hormones increase the strength of contractions, and stronger contractions trigger the release of more hormones, intensifying the contractions further. This describes choice D. Choices A and B describe responses that restore conditions toward normal, which are negative feedback.

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