5 Written questions
5 Matching questions
- True or false? Osmosis is a type of diffusion.
- A semipermeable membrane is placed between the following solutions. Which solution will increase in volume?
a) Solution C: 9% (m/v) NaCl
b) Solution D: 12.4% (m/v) NaCl
- Which of the following particles could diffuse easily through a cell membrane?
a) Oxygen (O2)
b) Hydrogen ion (H+)
c) Sodium ion (Na+)
- 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.
- What name is given to the process by which water crosses a selectively permeable membrane?
e) passive transport
- a c) It will move out of the vesicles.
- b a) Oxygen (O2) (Small nonpolar molecules such as oxygen can diffuse across cell membranes.)
- c True (Osmosis is the diffusion of water across a selectively permeable membrane.)
- d a) osmosis (Osmosis is the passive transport of water.)
- e 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 Multiple choice questions
- True (The hydrophilic, or water-loving, portion of a phospholipid is the polar head, whereas the hydrophobic portion is the nonpolar tail.)
- c) Amphipathic nature
- c) against the molecule's concentration gradient
- b) The polarity of membrane phospholipids
- 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.)
5 True/False 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. → 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.)
What distinguishes facilitated diffusion from simple diffusion?
a) Molecules move from a region of lower concentration to a region of higher concentration.
b) No energy is used to move molecules across the membrane.
c) Membrane proteins help move molecules across the membrane.
d) Molecules move from a region of higher concentration to a region of lower concentration. → b) The polarity of membrane phospholipids
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 → 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.)
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. → a) Lipids are mostly nonpolar.
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.)