In a phospholipid bilayer, the ()
A. phosphate groups are hydrophobic.
B. proteins are located only between the two layers.
C. fatty acid tails are hydrophilic.
D. phosphate heads are oriented toward the exterior of the cell or toward the cytoplasm.
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Molecules in the cell membrane that function as carriers are ()
A. proteins
B. glycerol
C. cholesterol
D. Phospholipids
Which of the following conditions is required for diffusion to occur? ()
ATP energy
B. A living cell
C. A concentration difference
D. A selectively-permeable membrane
Which of the following are structures that are not found in prokaryotic cells? ()
A. a membrane bound nucleus
B. mitochondria
C. Golgi bodies
D. all of the above
The basic unit of the living organism is ()
A. organ
B. Tissue
C. cell D) system
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