The walls of arteries are thicker than that of the veins. Why?​

What type of specimens where you able to see under each of the microscopes in the microscope activity

How does natural selection change thephenotypes within a population over time?

The image below shows a common blood pressure gauge. what does this device do? a. measures the level of oxygen present in the blood b. measures the pressure of blood when the lungs expand and compress c. measures the electrical activity of the heart d. measures the pressure of blood when the heart contracts and relaxes