Question

what role does the phospholipid bilayer play in the cell membrane?
a. it synthesizes proteins.
b. it produces energy for the cell.
c. it acts as a semi - permeable barrier, allowing selective transport of substances.
d. it stores genetic material.
what happens when a positive feedback loop reaches its end goal?
a. the loop triggers a negative feedback response.
b. the process continues indefinitely.
c. the loop immediately reverses itself.
d. the loop stops as the desired outcome has been achieved.
what role do platelets play in the positive feedback loop during blood clotting?
a. they release chemicals that attract more platelets to the injury site, amplifying the clotting process.
b. they regulate blood pressure during clotting.
c. they dissolve existing blood clots.
d. they prevent blood clot formation.
which of the following is an example of a positive feedback loop?
a. balancing water content in cells
b. regulating blood sugar levels
c. blood clotting after an injury
d. regulating body temperature

Explanation:

1. Proteins are synthesized by ribosomes, energy - producing organelles are mitochondria, and genetic material is stored in the nucleus. The phospholipid bilayer of the cell membrane acts as a semi - permeable barrier for selective transport.
2. In a positive feedback loop, the process continues to amplify until a certain endpoint is reached. When it reaches its end goal, the loop stops as the desired outcome has been achieved.
3. Platelets release chemicals that attract more platelets to the injury site, which is a key part of the positive feedback loop in blood clotting.
4. Balancing water content, regulating blood sugar levels, and regulating body temperature are examples of negative feedback loops. Blood clotting after an injury is a positive feedback loop as the initial event (injury) leads to an amplification of the clotting process.

Answer:

1. c. It acts as a semi - permeable barrier, allowing selective transport of substances.
2. d. The loop stops as the desired outcome has been achieved.
3. a. They release chemicals that attract more platelets to the injury site, amplifying the clotting process.
4. c. Blood clotting after an injury