Question

multiple choice question
platelet activation is an example of positive feedback. what does that mean?

activating one platelet leads to the activation of another platelet, and then another.

activating one platelet starts a cascade of fibrin formation.

activating one platelet leads to a positive outcome.

activating one platelet makes it more difficult to activate another.

Explanation:

To determine the correct answer, we analyze the concept of positive feedback in the context of platelet activation. Positive feedback in biological systems (like platelet activation) typically involves a process where an initial event (platelet activation) triggers more of the same event.

• The first option: "Activating one platelet leads to the activation of another platelet, and then another" fits the positive feedback mechanism, as one activated platelet promotes the activation of others, creating a self - amplifying loop.
• The second option is about fibrin formation, which is a downstream process of platelet activation, not the definition of positive feedback for platelet activation itself.
• The third option misinterprets positive feedback as a "positive outcome" in a general sense, but positive feedback in biology is about the amplification of a process, not a subjective positive result.
• The fourth option describes a negative feedback - like effect (making it harder to activate another platelet), which is the opposite of positive feedback.

Answer:

A. Activating one platelet leads to the activation of another platelet, and then another.