5 Written questions
5 Matching questions
- What name is given to the process by which water crosses a selectively permeable membrane?
e) passive transport
- A semipermeable membrane is placed between the following solutions. Which solution will decrease in volume?
a) Solution A: 1.4% (m/v) starch
b) Solution B: 7.62% (m/v) starch
- Lactose transport by membrane proteins occurs under conditions in which the concentration of lactose inside the cell is higher than the concentration outside the cell. What type of transport is used to move lactose into the cell?
a) Active transport
b) Simple diffusion
c) Facilitated diffusion
- The movement of molecules through a plasma membrane channel protein is always _____.
a) toward the inside of the cell
b) down the molecule's concentration gradient
c) against the molecule's concentration gradient
d) "paid for" by an expenditure of cellular energy
- Which membrane protein would be used to move glucose across a membrane from a region of higher concentration to a region of lower concentration?
b) No protein is necessary.
d) Ion channel
- a a) Active transport
(Under these conditions, lactose moves against its concentration gradient, so its transport will require energy.)
- b a) Transporter
(The GLUT-1 transporter assists the diffusion of glucose through the membrane.)
- c a) Solution A: 1.4% (m/v) starch (The water molecules actually move in both directions, but they move to a greater extent toward Solution B because it has a higher solute concentration than Solution A. The net movement of water molecules causes Solution A to decrease in volume and Solution B to increase in volume.)
- d c) against the molecule's concentration gradient
- e a) osmosis (Osmosis is the passive transport of water.)
5 Multiple choice questions
- c) Amphipathic nature
- d) Among the three types, only pumps can concentrate substances on one side of the membrane.
(Only pumps use energy (from ATP) to move substances against electrochemical gradients.)
- a) Oxygen (O2) (Small nonpolar molecules such as oxygen can diffuse across cell membranes.)
- a) The charge on the other side of the membrane is generally the opposite of the ion's charge.
(Ions tend to move toward regions of unlike charge.)
- b) Solution D: 12.4% (m/v) NaCl (The water molecules actually move in both directions, but they move to a greater extent toward Solution D because it has a higher solute concentration than Solution C. This net movement of water molecules causes Solution D to increase in volume and Solution C to decrease in volume.)
5 True/False questions
If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?
d) Isotonic → c) It will move out of the vesicles.
True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group. → True (The hydrophilic, or water-loving, portion of a phospholipid is the polar head, whereas the hydrophobic portion is the nonpolar tail.)
True or false? Osmosis is a type of diffusion. → False
True or false? During active transport through the sodium-potassium pump, ATP hydrolysis provides the energy to pump three sodium ions into the cell for every two potassium ions pumped out of the cell. → False
(The sodium-potassium pump maintains a state in which the concentration of sodium is low inside the cell relative to the outside and the concentration of potassium is high inside the cell relative to the outside; thus, three sodium ions are pumped out of the cell and two potassium ions are pumped into the cell against the electrochemical gradient.)
Lipid vesicles are formed so that they contain pure water. If these vesicles are transferred to a solution that contains a rather high concentration of solutes, what will be the net direction of water movement?
a) It will not move at all.
b) It depends on what solute is dissolved in the exterior solution.
c) It will move out of the vesicles.
d) It will move into the vesicles. → a) Hypotonic (The salt concentration in the solution is lower than it is in the cell, so water enters the cell, causing it to burst.)