11) Bulk movement of water across plasma membranes and the : 1402885
11) Bulk movement of water across plasma membranes and the exchange of oxygen from blood into cells are similar in that the method of transport is by
A) facilitated transport
D) active transport
E) sodium-potassium pumps
12) A student is designing an experiment to show the effects of the movement of water across a selectively permeable membrane. He places a highly concentrated saltwater solution into a bag that is permeable only to water. He then submerges the bag into a beaker of pure water. Which one of the following can be expected?
A) The net flow of water will be from the bag to the surrounding water.
B) The pH of the contents of the bag will increase over time.
C) The volume of the bag will decrease over time.
D) The net flow of water will be from the beaker into the bag, causing the contents of the bag to increase in volume.
E) In this situation, the flow of water into the bag will never equal the flow of water out of the bag.
13) Oxygen and carbon dioxide are able to pass through the plasma membrane of a cell because
A) they are both polar molecules
B) both are lipid soluble
C) they move through ion pores
D) each binds to a transport protein that "pulls" it across the membrane
E) they are small and nonpolar, and readily pass between phospholipids
14) Gated channels are especially important in regulating the transport of ________ across a plasma membrane.
D) small uncharged molecules
E) nucleic acids
15) Which one of the following best explains how water moves freely across a plasma membrane?
A) Water moves directly through the phospholipid bilayer because of the charges on phospholipids.
B) Water is brought into the cell by facilitated diffusion but released by exocytosis.
C) It is actively transported across the membrane.
D) Water moves through protein-lined channels in the plasma membrane.
E) The passage of water across a plasma membrane requires facilitated transport.
16) Which one of the following is TRUE regarding active transport?
A) Active transport requires the input of energy.
B) Molecules are moved across a plasma membrane from an area of higher concentration to an area of lower concentration.
C) Active transport relies on the process of diffusion.
D) Molecules to be transported attach to phospholipids in the plasma membrane; as the phospholipids change shape, the molecules are moved across the membrane.
E) This mechanism allows a cell to equalize the concentration of molecules on either side of the plasma membrane.
17) Active transport is like facilitated diffusion in that both processes
A) move molecules down their concentration gradient
B) require the presence of proteins in the plasma membrane that move molecules from one side of the plasma membrane to the other
C) require the conversion of ADP to ATP
D) do not require a source of energy
E) facilitate the movement of water through the phospholipids of the plasma membrane
18) To move solutes like amino acids into a cell by active transport, the cell
A) must possess appropriate transport proteins in the plasma membrane
B) must have a net gain in energy resulting from active transport
C) maintains a lower concentration of the amino acids in the cytoplasm
D) must move water out of the cytoplasm at the same time
19) Peptides and small proteins are generally too large to be transported into cells using transport proteins or moving through pores. The macromolecules are brought into the cell using
C) gated channels
E) open channels
20) The figure above shows a portion of the cell membrane. Which one of the following processes does it depict?
C) facilitated diffusion
D) gated channels