How is the vertebrate circulatorium an example of technology that benefits people

When a gasoline engine burns gasoline, what type of chemical reaction is occurring?

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

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above