The plasma membrane is a covalently linked network of phospholipids and proteins that controls the movement of solutes into and out of a cell.
	Phospholipids are the primary component that determines which solutes can cross the plasma membrane.
	Carbohydrates on the membrane surface are important in determining the overall bilayer structure.
	The hydrophilic interior of the membrane is composed primarily of the fatty acid tails of the phospholipids.
	The sides of the plasma membrane that face the cytoplasm and the outside of the cell have different lipid and protein composition.

	a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot
	two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins
	two layers of phospholipids with proteins embedded between the two layers
	two layers of phospholipids with proteins either crossing the layers or on the surface of the layers
	a fluid structure in which phospholipids and proteins move freely between sides of the membrane

	the size and polarity of the solute
	the types of transport proteins in the membrane
	the phospholipid composition of the membrane
	The first and second answers are both correct.
	The first three answers are all correct.

	polar interactions among the phospholipid head groups on the same surface of the membrane
	hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane
	hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane
	covalent interactions between the phospholipid and protein components of the membrane
	hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane

	Osmosis is the diffusion of water from a region of higher water concentration to a region of lower water concentration.
	If a solution outside the cell is hypotonic compared to the cytoplasm, water will move into the cell by osmosis.
	Osmotic movement of water into a cell would likely occur if the cell accumulates solutes from its environment.
	The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.
	If a cell is placed in an isotonic solution, water will enter the cell at the same rate that it leaves the cell.

	Transport proteins provide the energy for diffusion of the solute.
	Transport proteins provide a hydrophilic route for the solute to cross the membrane.
	Transport proteins organize the phospholipids to allow the solute to cross the membrane.
	Transport proteins provide a low-resistance channel for water molecules to cross the membrane.
	Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane.

	passive transport
	diffusion
	active transport
	osmosis
	any of the above

	passive diffusion of the glucose through the lipid bilayer
	ATP-dependent changes in the conformation of a transport protein that moves the glucose across the membrane
	facilitated diffusion of the glucose using a carrier protein
	cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis
	movement of glucose into the cell through a glucose channel

	Active transport is usually against the concentration gradient of the solute, whereas passive transport is always down the concentration gradient of the solute.
	Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.
	Active transport always requires the use of transport proteins, but passive transport can sometimes be accomplished without a protein.
	The first and second choices are correct.
	The first, second, and third choices are all correct.

	Both processes provide a mechanism for exchanging membrane-impermeable molecules between the inside and the outside of the cell.
	These two processes always require the participation of transport vesicles.
	Both endocytosis and exocytosis involve active transport.
	Exocytosis and endocytosis always result in a change in the surface area of the plasma membrane.
	The inner surface of a transport vesicle that fuses with or buds from the plasma membrane is most closely related to the outer surface of the plasma membrane.