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Multiple Choice
Which of the following is an example of a positive feedback loop?
A
Regulation of blood glucose levels by insulin
B
Secretion of parathyroid hormone in response to low blood calcium
C
The release of oxytocin during childbirth to intensify uterine contractions
D
Thermoregulation by sweating to cool the body
Verified step by step guidance
1
Step 1: Understand the concept of feedback loops. Feedback loops are mechanisms that organisms use to maintain homeostasis. A positive feedback loop amplifies or intensifies a response, while a negative feedback loop reduces or counteracts a change to maintain balance.
Step 2: Analyze the examples provided. For each example, determine whether the response amplifies the initial stimulus (positive feedback) or counteracts it (negative feedback).
Step 3: Evaluate the first example: 'Regulation of blood glucose levels by insulin.' This is a negative feedback loop because insulin lowers blood glucose levels, counteracting the initial rise in glucose.
Step 4: Evaluate the second example: 'Secretion of parathyroid hormone in response to low blood calcium.' This is also a negative feedback loop because the hormone works to increase calcium levels, counteracting the initial drop.
Step 5: Evaluate the third example: 'The release of oxytocin during childbirth to intensify uterine contractions.' This is a positive feedback loop because the release of oxytocin amplifies the contractions, which in turn stimulates more oxytocin release, intensifying the process until childbirth is complete.