Blood clotting is an example of how positive feedback works because it ______.

• A. maintains a constant level of clotting factors through continuous inhibition of thrombin
• B. prevents clot formation by reducing fibrin production as bleeding continues
• C. reverses the initial change to return the body to homeostasis by decreasing platelet activation
• D. amplifies a response as activated platelets release chemicals that recruit more platelets to the injury site

Answer: (D)

Verified step by step guidance

1. Understand the concept of positive feedback: it is a process where the output of a system amplifies or increases the original stimulus, leading to an enhanced response.
2. Identify the key components involved in blood clotting, such as platelets, thrombin, and fibrin, and recognize their roles in the clotting cascade.
3. Analyze how activated platelets contribute to the process by releasing chemicals that attract and activate more platelets, thus amplifying the clotting response.
4. Contrast positive feedback with negative feedback, noting that positive feedback does not maintain constant levels or reverse changes but instead intensifies the response until the clot is formed.
5. Conclude that blood clotting exemplifies positive feedback because the initial activation of platelets leads to a self-amplifying cycle that rapidly promotes clot formation at the injury site.