Life: The Science of Biology

David E. Sadava, David M. Hilliss, H. Craig Heller,May Berenbaum

Chapter 6

Cell Membranes - all with Video Answers

Educators

Chapter Questions

Problem 1

Which statement about membrane phospholipids is not true?
$a$. They associate to form bilayers.
b. They have hydrophobic "tails."
c. They have hydrophilic "heads."
$d$. They give the membrane fluidity.
e. They flip-flop readily from one side of the membrane to the other.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 2

When a hormone molecule binds to a specific protein on the plasma membrane, the protein it binds to is called a
$a .$ ligand.
$b .$ clathrin.
$c$ receptor protein.
$d$. hydrophobic protein.
$e .$ cell adhesion molecule.

Tate Hilken

Numerade Educator

Problem 3

Which statement about membrane proteins is not true?
$a. $They all extend from one side of the membrane to the other.
$b.$ Some serve as channels for ions to cross the membrane.
$c$. Many are free to migrate laterally within the membrane.
$d$. Their position in the membrane is determined by their tertiary structure
$e .$ Some play roles in photosynthesis.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 4

Which statement about membrane carbohydrates is $n o t$ true?
$a$. Some are bound to proteins.
$b .$ Some are bound to lipids.
$c. $They are added to proteins in the Golgi apparatus.
$d. $They show little diversity.
$e. $They are important in recognition reactions at the cell surface.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 5

Which statement about animal cell junctions is not true?
$a .$ Tight junctions are barriers to the passage of molecules between cells.
b. Desmosomes allow cells to adhere firmly to one another.
$c .$ Gap junctions block communication between adjacent cells.
d. Connexons are made of protein.
$e .$ The fibers associated with desmosomes are made of protein.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 6

You are studying how the protein transferrin enters cells. When you examine cells that have taken up transferrin, you find it inside clathrin-coated vesicles. Therefore, the most likely mechanism for uptake of transferrin is
$a .$ facilitated diffusion.
$b$. an antiporter.
$c .$ receptor-mediated endocytosis.
$d .$ gap junctions.
$e .$ ion channels.

Tate Hilken

Numerade Educator

Problem 7

Which statement about ion channels is not true?
a. They form pores in the membrane.
$b .$ They are proteins.
$c .$ All ions pass through the same type of channel.
dovement through them is from regions of high concentration to regions of low concentration.
$e .$ Movement through them is by simple diffusion.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 8

Facilitated diffusion and active transport both
$a$. require ATP.
$b$. require the use of proteins as carriers or channels.
c. carry solutes in only one direction.
$d$. increase without limit as the concentration gradient increases.
e. depend on the solubility of the solute in lipids.

Bryan Lynn

Numerade Educator

Problem 9

Primary and secondary active transport both
a. generate ATP.
$b$. are based on passive movement of $\mathrm{Na}^{+}$ ions.
$c$. include the passive movement of glucose molecules.
$d$. use ATP directly.
$e .$ can move solutes against their concentration gradients.

Tate Hilken

Numerade Educator

Problem 10

Which statement about osmosis is not true?
$a .$ It obeys the laws of diffusion.
$b$. In animal tissues, water moves into cells if they are hypertonic to their environment.
$c .$ Red blood cells must be kept in a plasma that is hypotonic to the cells.
d. Two cells with identical solute concentrations are isotonic to each other.
e. Solute concentration is the principal factor in osmosis.

Shazia Naz

Numerade Educator