How does mutation enable viruses to continue causing disease?

What are the doorways into and out of cells, attached to the membrane, and built in the rough er.

Compare the composition of the moon's surface with the composition of the earth's surface.

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