Lecture 6 & 7 Flashcards
Which of the following statements about a typical plasma membrane is correct?
a. Phospholipids are the primary component that determines which solutes can cross the plasma membrane
b. Carbohydrates on the membrane surface are important in determining the overall bilayer structure.
c. The plasma membrane is a covalently linked network of phospholipids and proteins that controls the movement of solutes into and out of a cell.
d. The two sides of the plasma membrane have different lipid and protein composition.
e. The hydrophilic interior of the membrane is composed primarily of the fatty acid tails of the phospholipids.
d. The two sides of the plasma membrane have different lipid and protein composition.
The permeability of a biological membrane to a specific polar solute may depend on which of the following?
a. the amount of cholesterol in the membrane
b. the types of transport proteins in the membrane
c. the phospholipid composition of the membrane
d. the presence of unsaturated fatty acids in the membrane
e. the types of polysaccharides present in the membrane
b. the types of transport proteins in the membrane
Which of the following statements about osmosis is correct?
a. Osmosis is the diffusion of water from a region of lower water concentration to a region of higher water concentration.
b. If a solution outside the cell is hypertonic compared to the cytoplasm, water will move into the cell by osmosis.
c. Osmotic movement of water into a cell would likely occur if the cell accumulates water from its environment.
d. The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.
e. If a cell is placed in an isotonic solution, more water will enter the cell than leaves the cell.
d. The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.
In facilitated diffusion, what is the role of the transport protein?
a. Transport proteins provide a hydrophilic route for the solute to cross the membrane.
b. Transport proteins provide a low-resistance channel for water molecules to cross the membrane.
c. Transport proteins organize the phospholipids to allow the solute to cross the membrane.
d. Transport proteins provide the energy for diffusion of the solute.
e. Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane.
a. Transport proteins provide a hydrophilic route for the solute to cross the membrane.
Active and passive transport of solutes across a membrane typically differ in which of the following ways?
a. Active transport is usually down the concentration gradient of the solute, whereas passive transport is always against the concentration gradient of the solute.
b. Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.
c. Active transport is always faster than passive transport.
d. Active transport uses protein carriers, whereas passive transport uses carbohydrate carriers.
e. Active transport is used for ions, passive transport is used for uncharged solutes.
b. Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.
If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol?
a. passive transport
b. diffusion
c. active transport
d. osmosis
e. facilitated diffusion
c. active transport
Which of the following correctly describes some aspect of exocytosis or endocytosis?
a. Endocytosis and exocytosis involve passive transport.
b. Both processes provide a mechanism for exchanging membrane-impermeable molecules between the organelles and the cytosol.
c. Exocytosis and endocytosis change the surface area of the plasma membrane.
d. These two processes require the participation of mitochondria.
e. The inner surface of a transport vesicle that fuses with or buds from the plasma membrane is most closely related to the inner surface of the plasma membrane.
c. Exocytosis and endocytosis change the surface area of the plasma membrane.
