The opening and closing of the heart valves is caused by Multiple Choice action potentials within the cusps of the valves. pressure changes of alternating contraction and relaxation during the cardiac cycle. contraction and relaxation of papillary muscles that pull on heart strings. contraction of the smooth muscle in the walls of the great vessels leaving the heart.

Two male mice, which we will call male a and male b, are both phenotypically normal. male a was from a litter that contained half phenotypically normal mice and half dwarf mice. the mother of male a was known to be homozygous for the normal igf2 allele. male b was from a litter of eight mice that were all phenotypically normal. the parents of male b were a phenotypically normal male and a dwarf female. male a and male b were put into a cage with two female mice that we will call female a and female b. female a is a dwarf and female b is phenotypically normal. the parents of these two females were unknown, although it was known that they were from the same litter. the mice were allowed to mate with each other, and the following data were obtained: female a gave birth to three dwarf babies and four normal babies. female b gave birth to four normal babies and two dwarf babies. which male(s)mated with female a and female b? male a with both females male a with female b, and male b with female a male a with female a, and male b with female b could not be determined male b with both females

Researchers want to use edna to look for an invasive species in the water which of the steps would be likely do last

When mendel crossed a true-breeding short plant with a true-breeding tall plant all the offspring were tall. which term describes the gene for tallnes?