Final answer:
The statement is true; positive feedback in the body normally occurs when there is a definite endpoint, as seen in processes like childbirth and blood clotting. These loops amplify or intensify a physiological response until an outcome is achieved.
Step-by-step explanation:
The statement that positive feedback in the body is normal only when there is a definite end point is true. Positive feedback loops are control mechanisms that serve to amplify or intensify a response until an endpoint is reached. This type of feedback is less common compared to negative feedback because it causes conditions to deviate further from normal levels.
Examples of positive feedback include the process of childbirth, where uterine contractions increase in intensity until the baby is delivered. Another example is blood clotting, wherein the body intensifies the response to blood loss by forming a clot that stops the bleeding. Both of these examples have clear endpoints: the delivery of the baby and the cessation of bleeding.
Therefore, while most hormonal regulation in the body operates under negative feedback mechanisms, maintaining homeostasis, certain critical processes such as during childbirth or in response to blood loss, involve positive feedback loops that are designed to ensure a particular outcome is achieved, thereby marking their endpoints.