Question 12

Insulin decreases the concentration of blood glucose.

Insulin is a hormone produced by the pancreas that plays a crucial role in regulating blood glucose levels by facilitating the uptake of glucose into cells, thereby lowering blood sugar levels.

A) insulin

This option is correct because insulin directly lowers blood glucose levels by promoting the absorption of glucose by tissues, particularly muscle and fat cells. When blood sugar levels are elevated, insulin is secreted to help transport glucose from the bloodstream into the cells, reducing overall blood glucose concentration.

B) glucagon

Glucagon is incorrect as it serves the opposite function to insulin. It is a hormone that raises blood glucose levels by stimulating the liver to release stored glucose into the bloodstream, thus increasing blood sugar concentration when it is low.

C) growth hormone

Growth hormone is not primarily involved in glucose regulation. Instead, it can actually increase blood glucose levels by promoting gluconeogenesis and reducing glucose uptake in certain tissues. Therefore, it does not decrease blood glucose concentration.

D) glucocorticoids

Glucocorticoids are steroid hormones that can lead to an increase in blood glucose levels. They promote gluconeogenesis and inhibit the effects of insulin, making them counterproductive in lowering blood glucose concentration.

Conclusion

Insulin is definitively the hormone that decreases blood glucose levels by enhancing glucose uptake in cells. In contrast, glucagon, growth hormone, and glucocorticoids all contribute to increasing blood glucose levels or reducing insulin's effectiveness, making them incorrect choices for this question.