Define these terms: artery, arteriole, capillary bed, venule, and vein. why do capillaries have sphincters?

Capillaries are the smallest-diameter blood vessels that connect the smallest arterioles to the smallest venules, they have sphincters to control the blood distribution, based on the body's demands, the can relax or constrict so the blood can follow specific pathways to meet the tissue's necessities.

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what have scientists found to be the most efficient and effective way to insert new sequences into an individual? a-scientists have created genetically altered foods that release dna during digestion. b-scientists use viruses to insert specific gene sequences. c-scientists irradiate genes so that they can be absorbed through the skin.

the answer is trees if i'm not mistaken