Biology: The Dynamic Science

Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter 5

Membranes and Transport - all with Video Answers

Educators

Chapter Questions

Problem 1

In the fluid mosaic model:
a. plasma membrane proteins orient their hydrophilic sides toward the internal bilayer.
b. phospholipids often flip-flop between the inner and outer layers.
c. the mosaic refers to proteins attached to the underlying cytoskeleton.
d. the fluid refers to the phospholipid bilayer.
e. the mosaic refers to the symmetry of the internal membrane proteins and sterols.

Joanna Quigley

Joanna Quigley

Numerade Educator

Problem 2

Which of the following statements is false? Proteins in the plasma membrane can:
a. transport ions.
b. transport chloride ions when there are two mutant copies of the cystic fibrosis transmembrane conductance regulator gene.
c. recognize self versus foreign molecules.
d. allow adhesion between the same tissue cells or cells of different tissues.
e. combine with lipids or sugars to form complex macromolecules.

Joanna Quigley

Numerade Educator

Problem 3

The freeze-fracture technique demonstrated:
a. that the plasma membrane is a bilayer with individual proteins suspended in it.
b. that the plasma membrane is fluid.
c. that the arrangement of membrane lipids and proteins is symmetric.
d. that proteins are bound to the cytoplasmic side but not embedded in the lipid bilayer.
e. the direction of movement of solutes through the membrane.

Joanna Quigley

Numerade Educator

Problem 4

A characteristic of carrier molecules in a primary active transport pump is that:
a. they cannot transport a substance and also hydrolyze ATP.
b. they retain their same shape as they perform different roles.
c. their primary role is to move negatively charged ions across membranes.
d. they move Na $^{+}$ into a neural cell and $\mathrm{K}^{+}$ out of the same cell.
e. they act to establish an electrochemical gradient.

Joanna Quigley

Numerade Educator

Problem 5

A driving ion moving through a membrane channel in one direction gives energy to actively transport another molecule in the opposite direction. What is this process called?
a. facilitated diffusion
b. antiport transport
c. symport transport
d. primary active transport pump
e. cotransport

Emily Himsel

Numerade Educator

Problem 6

Phagocytosis illustrates which phenomenon?
a. receptor-mediated endocytosis
b. bulk endocytosis
c. exocytosis
d. pinocytosis
e. cotransport

Emily Himsel

Numerade Educator

Problem 7

Place in order the following events of receptor-mediated endocytosis.
(1) Clathrin coat disappears.
(2) Receptors collect in a coated pit covered with clathrin on the cytoplasmic side.
(3) Receptors recognize and bind specific molecules.
(4) Endocytic vesicle may fuse with lysosome whereas receptors are recycled to the cell surface.
(5) Pits deepen and pinch free of plasma membrane to form endocytic vesicles.
a. 4,1,2,5,3
b. 2,1,3,5,4
c. 3,2,5,1,4
d. 4,1,5,2,3
e. 3,1,2,4,5

Joanna Quigley

Numerade Educator

Problem 8

In the following figure, assume that the setup was left unattended. Which of the following statements is correct?
a. The relation of the cell to its environment is isotonic.
b. The cell is in a hypertonic environment.
c. The net flow of solvent is into the cell.
d. The cell will soon shrink
e. Diffusion can occur here but not osmosis.

Joanna Quigley

Numerade Educator

Problem 9

Which of the following statements is true for the figure in question $8 ?$
a. The net movement of solutes is into the cell.
b. There is no concentration gradient.
c. There is a potential for plasmolysis.
d. The solvent will move against its concentration gradient.
e. If this were a plant cell, turgor pressure would be maintained.

Josee Pacheco

Numerade Educator

Problem 10

Using the principle of diffusion, a dialysis machine removes waste solutes from a patient's blood. Imagine blood runs through a cylinder wherein diffusion can occur across an artificial selectively permeable membrane to a saline solution on the other side. Which of the following statements is correct?
a. Solutes move from lower to higher concentration.
b. The concentration gradient is lower in the patient's blood than in the saline solution wash.
c. The solutes are transported through a symport in the blood cell membrane.
d. The saline solution has a lower concentration gradient of solute than the blood.
e. The waste solutes are actively transported from the blood.

Joanna Quigley

Numerade Educator

Problem 11

The bacterium Vibrio cholerae causes cholera, a disease characterized by severe diarrhea that may cause infected people to lose up to $20 \mathrm{L}$ of fluid in a day. The bacterium enters the body when someone drinks contaminated water. It adheres to the intestinal lining, where it causes cells of the lining to release sodium and chloride ions. Explain how this release is related to the massive fluid loss.

Emily Himsel

Numerade Educator

Problem 12

Irrigation is widely used in dryer areas of the United States to support agriculture. In those regions, the water evaporates and leaves behind deposits of salt. What problems might these salt deposits cause for plants?

Emily Himsel

Numerade Educator

Problem 13

In hospitals, solutions of glucose with a concentration of $0.3 \mathrm{M}$ can be introduced directly into the bloodstream of patients without tissue damage by osmotic water movement. The same is true of $\mathrm{NaCl}$ solutions, but these must be adjusted to $0.15 \mathrm{M}$ to be introduced without damage. Explain why one solution is introduced at $0.3 \mathrm{M}$ and the other at $0.15 \mathrm{M}$.

Josee Pacheco

Numerade Educator

Problem 14

Design an experiment to determine the concentration of $\mathrm{NaCl}$ (table salt) in water that is isotonic to potato cells. Use only the following materials: a knife, small cookie cutters, and a balance.

Josee Pacheco

Numerade Educator

Problem 15

What evidence would convince you that membranes and active transport mechanisms evolved from an ancestor common to both prokaryotes and eukaryotes?

Emily Himsel

Numerade Educator