What is true about heart valves? a. they enforce a one-way blood flow through the heart. b. they operate passively (no active contraction required). c. they separate atria from ventricles, and ventricles from the large arteries that leave them. d. they enforce a one-way blood flow through the heart, operate passively (no active contraction required), and separate atria from ventricles, and ventricles from the large arteries that leave them?

Abody cell has been growing and at synthesis proteins.in the nucleus of this body cell,dna replication is taking place. and a copy of the cells genetic material is copied.which of the following is the best conclusion you can make about the life cycle of this cell ? a) the cell is ready to undergo mitosis.and a chemical signal will send the cell to prophase b)the cell is undergoing meiosis and will cross over the genetic material next c)the cell is in the s phase of interphase and will move next to the g2 phase d) the cell is in the g2 phase of the interphase and is ready to begin diving