No system is closed off by it surroundings.
That would refer to naked seeds :)
Answer:
d) A negative feedback loop
Explanation:
A negative feedback loop counteracts the deviation from homeostasis by generating a required response. The function of the insulin hormone is to lower down the blood glucose level when it raises above the normal range. Insulin triggers the uptake of glucose from the blood by cells. It specifically triggers muscle and liver cells to take up glucose from the blood.
Once the blood glucose level is restored to the normal value, the secretion of insulin stops. Here, a change in normal body condition (raised blood glucose level) was counteracted by the secretion of insulin hormone to restore the homeostasis of blood sugar levels.
