BIO 131 Test Quizzes Latest 2026 With Answers
What are carrier proteins?
bind to molecules and change shape to shuttle them across the membrane
Good Example of Carrier Protein from Txtbook
For example, a glucose carrier protein in the plasma membrane of red blood cells
transports glucose across the membrane 50,000 times faster than glucose can pass
through on its own. This glucose transporter is so selective that it even rejects fructose, a
structural isomer of glucose.
What is diffusion?
The random thermal motion of particles of liquids, gases, or solids. In the presence of a
concentration or electrochemical gradient, diffusion results in the net movement of a
substance from a region where it is more concentrated to a region where it is less
concentrated.
What is concentration gradient?
A region along which the density of a chemical substance increases or decreases.
In the absence of other forces, a substance will diffuse from...
where it is more concentrated to where it is less concentrated.
Does diffusion require energy?
No
, Oxygen Diffusion Example from the Txtbook
Dissolved oxygen diffuses into the cell across the plasma membrane. As long as cellular
respiration consumes the O2O2 as it enters, diffusion into the cell will continue because
the concentration gradient favors movement in that direction.
What is passive transport?
Passive transport is the diffusion of a substance across a biological membrane that
requires no energy.
What is osmosis?
The diffusion of free water molecules across a selectively permeable membrane.
What is tonicity?
The ability of a solution surrounding a cell to cause that cell to gain or lose water.
What is isotonic?
there will be no net movement of water across the plasma membrane. Water diffuses at
the same rate in both directions. In an isotonic environment, the volume of an animal cell
is stable.
What is hypertonic?
Referring to a solution that, when surrounding a cell, will cause the cell to lose water.
The cell will lose water, shrivel, and probably die.
What are carrier proteins?
bind to molecules and change shape to shuttle them across the membrane
Good Example of Carrier Protein from Txtbook
For example, a glucose carrier protein in the plasma membrane of red blood cells
transports glucose across the membrane 50,000 times faster than glucose can pass
through on its own. This glucose transporter is so selective that it even rejects fructose, a
structural isomer of glucose.
What is diffusion?
The random thermal motion of particles of liquids, gases, or solids. In the presence of a
concentration or electrochemical gradient, diffusion results in the net movement of a
substance from a region where it is more concentrated to a region where it is less
concentrated.
What is concentration gradient?
A region along which the density of a chemical substance increases or decreases.
In the absence of other forces, a substance will diffuse from...
where it is more concentrated to where it is less concentrated.
Does diffusion require energy?
No
, Oxygen Diffusion Example from the Txtbook
Dissolved oxygen diffuses into the cell across the plasma membrane. As long as cellular
respiration consumes the O2O2 as it enters, diffusion into the cell will continue because
the concentration gradient favors movement in that direction.
What is passive transport?
Passive transport is the diffusion of a substance across a biological membrane that
requires no energy.
What is osmosis?
The diffusion of free water molecules across a selectively permeable membrane.
What is tonicity?
The ability of a solution surrounding a cell to cause that cell to gain or lose water.
What is isotonic?
there will be no net movement of water across the plasma membrane. Water diffuses at
the same rate in both directions. In an isotonic environment, the volume of an animal cell
is stable.
What is hypertonic?
Referring to a solution that, when surrounding a cell, will cause the cell to lose water.
The cell will lose water, shrivel, and probably die.
