Final answer:
Negative feedback mechanisms maintain homeostasis by counteracting changes, while positive feedback mechanisms amplify changes, pushing the system away from its initial state. An example of negative feedback is the regulation of blood sugar, and an example of positive feedback is childbirth.
Step-by-step explanation:
Negative feedback mechanisms are essential in maintaining homeostasis within an organism, countering deviations by initiating responses to bring the system back to equilibrium. For example, the regulation of blood sugar levels by insulin is a negative feedback loop. Conversely, positive feedback mechanisms enhance the original stimulus, leading to a greater response; a well-known example is the release of oxytocin during childbirth which intensifies muscle contractions.
In the context of biology, negative feedback often helps to stabilize physiological systems, making it more common than positive feedback. Positive feedback, while less common, plays crucial roles in certain situations such as blood clotting and labor during childbirth. Together, these feedback systems ensure that organisms can maintain internal stability while also being able to undergo necessary physiological changes.
It is a misconception that positive feedback mechanisms balance amounts of substances or fill deficits, as stated in incorrect references (b) and (c). Instead, they push the system further from its initial state, as correctly noted in reference (a). Reference (a) provides the most accurate definition of feedback mechanisms.