Questions: 1 What is the action of insulin? Multiple Choice Decreases concentration of blood glucose Increases concentration of blood glucose Decreases permeability of cell membranes to glucose Increases breakdown of glycogen to release glucose

The answer is the first one: Decreases concentration of blood glucose.

Explanation for each option:

1. Decreases concentration of blood glucose: This is correct. Insulin is a hormone produced by the pancreas that helps lower blood glucose levels by facilitating the uptake of glucose into cells, particularly muscle and fat cells, and by inhibiting the production of glucose by the liver.

2. Increases concentration of blood glucose: This is incorrect. Insulin's primary function is to lower blood glucose levels, not increase them. The hormone that increases blood glucose levels is glucagon.

3. Decreases permeability of cell membranes to glucose: This is incorrect. Insulin actually increases the permeability of cell membranes to glucose by promoting the insertion of glucose transporter proteins (such as GLUT4) into the cell membrane, allowing glucose to enter the cells more easily.

4. Increases breakdown of glycogen to release glucose: This is incorrect. Insulin promotes the storage of glucose as glycogen in the liver and muscles, rather than breaking it down. The hormone that increases the breakdown of glycogen to release glucose is glucagon.

Summary: Insulin decreases the concentration of blood glucose by promoting the uptake of glucose into cells and inhibiting glucose production by the liver.