Question

activity 1/2
rs: feedback loops
multiple - choice question
what is the role of insulin?
to allow glucose to enter the blood stream
to encourage glucose to stay in the blood stream
to allow glucose to enter the cell
rewatch

Explanation:

Insulin is a hormone produced by the pancreas. Its main role is to regulate blood glucose levels. When blood glucose levels rise (for example, after a meal), the pancreas releases insulin. Insulin acts on cells (such as muscle, fat, and liver cells) by binding to insulin receptors on the cell membrane. This binding triggers a series of events that allow glucose transporters (such as GLUT - 4) to move to the cell membrane. As a result, glucose can enter the cells from the bloodstream. Once inside the cells, glucose can be used for energy production (through processes like glycolysis, the citric acid cycle, and oxidative phosphorylation) or stored (for example, as glycogen in liver and muscle cells or as fat in adipose cells).

Now let's analyze each option:

• The option "to allow glucose to enter the blood stream" is incorrect. Glucose enters the bloodstream mainly through the digestion and absorption of carbohydrates in the digestive tract (e.g., glucose is absorbed from the small intestine into the bloodstream). Insulin does not play a role in this process.
• The option "to encourage glucose to stay in the blood stream" is also incorrect. If glucose were to stay in the bloodstream, blood glucose levels would remain high, which is not the normal physiological function of insulin. High blood glucose levels (hyperglycemia) can cause various health problems if not regulated.
• The option "to allow glucose to enter the cell" is correct. As explained above, insulin facilitates the uptake of glucose by cells, which helps in maintaining normal blood glucose levels and providing cells with the energy - rich molecule (glucose) they need.

Answer:

to allow glucose to enter the cell