In radishes, the gene that controls color exhibits incomplete dominance. Pure-breeding red radishes crossed with pure breeding white radishes make purple radishes. What are the
phenotypic ratios when you cross a purple radish with a white radish? (simplify all ratios)

i think it is dna, i'm not totally sure but i think it might be.

answer; both surfaces of the membrane are nonpermeable

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.