5 Written questions
5 Matching questions
- 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
- 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.
- 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 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
- What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?
a) Hydrophobic nature
c) Amphipathic nature
d) Solubility in water
- a a) Oxygen (O2) (Small nonpolar molecules such as oxygen can diffuse across cell membranes.)
- b c) Amphipathic nature
- c b) The polarity of membrane phospholipids
- d 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.)
- e a) Transporter
(The GLUT-1 transporter assists the diffusion of glucose through the membrane.)
5 Multiple choice questions
- c) Membrane proteins help move molecules across the membrane.
- a) Active transport
(Under these conditions, lactose moves against its concentration gradient, so its transport will require energy.)
- a) osmosis (Osmosis is the passive transport of water.)
- True (The hydrophilic, or water-loving, portion of a phospholipid is the polar head, whereas the hydrophobic portion is the nonpolar tail.)
5 True/False questions
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 → True (Osmosis is the diffusion of water across a selectively permeable membrane.)
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.)
True or false? Osmosis is a type of diffusion. → False
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 → 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.)
How can a lipid be distinguished from a sugar?
a) Lipids are mostly nonpolar.
b) Lipids are mostly saturated.
c) A lipid dissolves in water.
d) A lipid is made up of only hydrocarbons. → c) Membrane proteins help move molecules across the membrane.