A positive feedback loop is characterized by what?

• A. Negative feedback loop
• B. Positive feedback loop
• C. Homeostatic loop
• D. Feedforward loop

Answer: (B)

Positive feedback loops amplify the initial change by promoting more of the same response. In this type of regulation, the output acts to speed up or intensify the original stimulus rather than dampening it. Because of that, the system moves away from its starting point and the response grows larger until some external event terminates the process. Classic examples include the blood-clotting cascade, where each step releases signals that recruit more platelets and accelerate clot formation, and labor, where oxytocin-driven contractions become stronger until delivery ends the process.

This is different from negative feedback loops, which act to counteract deviations from a set point and bring conditions back toward stability. A homeostatic loop is a general term for maintaining internal balance, often via negative feedback, rather than describing a mechanism that continually escalates. A feedforward loop involves anticipating changes rather than responding to an ongoing change with amplification. Therefore, the characteristic described—progressively increasing output in response to a stimulus—is a hallmark of a positive feedback loop.