Damaged tissue releases chemicals that activate platelets and stimulate the formation of blood clots. which of the following predictions about the activity of platelets best describes a positive feedback mechanism?

a. activated platelets release chemicals that inhibit blood clot formation.
b. activated platelets release signaling molecules that inhibit cell division in damaged tissue.
c. activated platelets constrict the blood vessels, stopping blood flow.
d. activated platelets release chemicals that activate more platelets.

D. Activated platelets release chemicals that activate more platelets.

Explanation:

When a stimulus or a change in some condition triggers a response that intensifies the changing condition, the mechanism is called a positive feedback mechanism.

Any damage to tissues makes the platelets to contact and stick to parts such as collagen fibers of the connective tissue present under the damaged endothelial cells. This process of platelet adhesion activates the platelets and brings about changes in them. The activated platelets grow many projections to contact and interact with one another. They also release ADP and thromboxane A2 which in turn activates the nearby platelets. The ADP makes other platelets in the area sticky. The stickiness of the newly recruited and activated platelets causes them to join the originally activated platelets. Eventually, the accumulation and attachment of large numbers of platelets form a platelet plug.

Here, release of chemicals from the activated platlets to activate more platlets represents the positive feedback mechanism.

hey, i believe your answer would be d. sugar ribose and the base uracil. i believe this is the answer, because rna consists of sugar ribose, adenine, guanine, cytosine, and uracil.

your first option is incorrect, because that's dna. where it consists of sugar deoxyribose, adenine, guanine, cytosine and thymine.

your second option is also incorrect, this is because sugar deoxyribose is in dna, and uracil is in rna. these two do not make sense together.

your third option being incorrect, because sugar ribose is in rna, but not the base of thymine. rna consists of uracil, not thymine.

lastly your fourth option being correct! this answer is correct, because both sugar ribose, and the base uracil are in rna! ~

answer is d. sugar ribose and the base uracil.

question: which statement best describes the different properties of metals?

answer: they are shiny and bend without breaking.

since metals have certain characteristics properties, they include the following: they are ductile, malleable, shiny, hard, lustrous, flexible and they are good conductor of heat and electricity. so therefore, metals are not dull and they are not non-flexible as listed. instead, they are shiny and flexible.

hope this , have a good day. c;