Q. Which of the following is an example of negative feedback loop in humans?
A) secretion of tears after falling of sand particles into the eye
B) salivation of mouth at the sight of delicious food
C) secretion of sweat glands and constriction of skin blood vessels when it is too hot
D) constriction of skin blood vessels and contraction of skeletal muscles when it is too cold
Explanation
[Solution from source] When body temperature falls, the hypothalamus triggers skin vasoconstriction and shivering to bring it back up, a response that opposes the change: negative feedback. The 'too hot' option is wrong because heat causes vasodilation, not constriction, while tears and salivation are simple reflexes. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.