本题目来源于试卷: Continuity and Change D.9 Homeostasis，类别为 IB生物学
[单选题]
Which statements are true of4o40s-iysi2sak hvpx/x,n 8x feedback mechanisms in an orqqyc ya qi/;z o2:kyy /k28:axganism?
I. Negative feedback acts to reverse a change
II. An example of positive feedback is control of blood pH
III. Only the nervous system is involved in the control of feedback mechanisms
A. I only
B. II only
C. I and III only
D. I, II and III
参考答案: A
本题详细解析:
Negative feedback is a regulatory mechanism in which the body responds to a change in order to return the homeostatic variable back to within its set points. For example, if blood pH increases above the set point, negative feedback mechanisms will occur to bring blood pH back down. Statement I is therefore true and Statement II is therefore false. Choices B and D are not correct. While the nervous system plays a significant role in many feedback mechanisms, it is not the only system involved. The endocrine system, which releases hormones into the bloodstream also plays a crucial role in feedback control. Statement III is therefore false, meaning Choice B is incorrect, and Choice A is the correct response to the question.
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