5 Written questions
5 Matching questions
- In cells, membrane proteins are responsible for the passage of substances that can't cross the membrane on their own. Channels and transporters are involved in facilitated diffusion. Pumps are involved in active transport. In terms of their properties or functions, which statement most accurately describes how these three types of membrane proteins compare?
a) Among the three types, only pumps are thought to undergo a shape change as part of their function.
b) Pumps are selective; channels and transporters are not selective.
c) Channels and transporters are integral membrane proteins; pumps are peripheral membrane proteins.
d) Among the three types, only pumps can concentrate substances on one side of the membrane.
- 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.
- Which of the following particles could diffuse easily through a cell membrane?
a) Oxygen (O2)
b) Hydrogen ion (H+)
c) Sodium ion (Na+)
- Which of the following transporters does not use passive transport to move molecules across a membrane?
a) Sodium-potassium pump
b) Gramicidin ion channel
d) GLUT-1 glucose transporter
- True or false? Active transport differs from passive transport in that active transport does not require an input of energy.
- a a) Sodium-potassium pump
(This pump uses the energy provided by ATP hydrolysis to transport sodium and potassium ions across the membrane.)
- b 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.)
- c False
- d c) It will move out of the vesicles.
- e a) Oxygen (O2) (Small nonpolar molecules such as oxygen can diffuse across cell membranes.)
5 Multiple choice questions
(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.)
- a) Active transport
(Under these conditions, lactose moves against its concentration gradient, so its transport will require energy.)
- a) Transporter
(The GLUT-1 transporter assists the diffusion of glucose through the membrane.)
- c) against the molecule's concentration gradient
- True (Osmosis is the diffusion of water across a selectively permeable membrane.)
5 True/False questions
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 (Osmosis is the diffusion of water across a selectively permeable membrane.)
Which of the following factors does not affect membrane permeability?
a) The saturation of hydrocarbon tails in membrane phospholipids
b) The polarity of membrane phospholipids
d) The amount of cholesterol in the membrane → a) Oxygen (O2) (Small nonpolar molecules such as oxygen can diffuse across cell membranes.)
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.
What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?
a) Hydrophobic nature
c) Amphipathic nature
d) Solubility in water → c) Amphipathic nature
What name is given to the process by which water crosses a selectively permeable membrane?
e) passive transport → a) osmosis (Osmosis is the passive transport of water.)