Which portion of the cell membrane is responsible for preventing unwanted materials from entering the cell? a. integral protein b. glycoprotein c. lipid bilayer d. cholesterol

Which macromolecules are polymers made of nucleotides (a) fatty acids (b) nucleic acids (c) carboxylic acids (d) amino acides

Match the examples to the correct level of organization. 1. system level roses, snakes, puppies 2. organism level roots, stamens, leaves 3. tissue level bone, cartilage, blood 4. organ level heart, veins, arteries

Blood stem cells may develop into any kind of human blood cells. what kind of stem cells are blood stem cells? a. multipotent stem cells o b. totipotent stem cells o c. pluripotent stem cells o d. unipotent stem cells