17. Which substance on the plasma membrane helps identify chemical signals from outside the cell? a. receptor proteins b. transport proteins c. marker proteins d. cholesterol​

Compare and contrast the adaptations of free-living flatworms and parasitic flatworms

How do the evolutionary chart and the video support the claim that all living things are made up of cells?

What is a difference between systemic and pulmonary circulation? a. systemic circulation carries oxygenated blood to the lungs and pulmonary circulation carries deoxygenated blood to the body. b. systemic circulation carries deoxygenated blood to the lungs and pulmonary circulation carries oxygenated blood to the body. c. systemic circulation carries deoxygenated blood to the body and pulmonary circulation carries oxygenated blood to the lungs. d. systemic circulation carries oxygenated blood to the body and pulmonary circulation carries deoxygenated blood to the lungs.