Platyhelminthes have flame cells. what is their significance?

they in respiration.

they in excretion.

they in protection.

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins

An alaskan spruce forest will burn easily once burned the forest regenerates fairly wuickly which statement best describes haw an alaskan spruce forest reacts to fire? it is resilient

What determines whether a particular cell is able to respond to a hormone?