How do the phospholipids in archaea differ from those in other cells? a. They have tails made of unsaturated fatty acids instead of saturated fatty acids. b. They do not contain hydrocarbon chains. c. They have isoprenoid tails instead of fatty acid tails. d. They have two hydrocarbon chains instead of three hydrocarbon chains.

What is a fiber composite? How do cellular fiber composites resemble reinforced concrete?

A cell is placed in a solution that is hypotonic to the cell. Which of the following best describes movement of water in this situation? a. Water will only flow into the cell. b. Water will only flow out of the cell. c. Water will flow into and out of the cell, but the overall net movement will be out of the cell. d. Water will flow into and out of the cell, but the overall net movement will be into the cell.

If a solution surrounding a cell is hypertonic relative to the inside of the cell, how will water move? a. It will move into the cell via osmosis. b. It will move out of the cell via osmosis. c. It will not move, because equilibrium exists. d. It will evaporate from the cell surface more rapidly.

Where are protein components of the extracellular matrix synthesized? a. in the rough ER b. in the Golgi apparatus c. in the plasma membrane d. in the extracellular layer itself

What two conditions must be present for osmosis to occur?Integral membrane proteins are anchored in lipid bilayers.

Which of the following groups of amino acid residues (see Ch. 3, Figure 3.2) would likely be found in the portion that crosses the lipid bilayer? a. acidic b. basic c. polar uncharged d. nonpolar

Cooking oil lipids consist of long, unsaturated hydrocarbon chains. Would you expect these molecules to form membranes spontaneously? Why or why not? Describe, on a molecular level, how you would expect these lipids to behave in water.

How do the extracellular filaments in plants differ from those in animals? a. Plant filaments resist compression forces; animal filaments resist pulling forces. b. Animal filaments consist of proteins; plant filaments consist of polysaccharides. c. Plant extracellular filaments never move; animal filaments can slide past one another. d. Plant filaments run parallel to one another; animal filaments crisscross.

Draw and label the plasma membrane of a cell that is placed in a solution with concentrations of calcium ions and lactose that are greater than those on the inside of the cell. Use arrows to show the relevant gradients and the activity of the following membrane proteins: (1) a pump that exports protons; (2) a calcium channel; and (3) a lactose carrier.

In terms of structure, how do channel proteins differ from carrier proteins?

Suppose a cell is placed in a solution with a high concentration of potassium and no sodium. How would the cellular sodium–potassium pump function in this environment? a. It would stop moving ions across the membrane. b. It would continue using ATP to pump sodium out of the cell and potassium into the cell. c. It would move sodium and potassium ions across the membrane, but no ATP would be used. d. It would reverse the direction of sodium and potassium ions to move them against their gradients.

In an experiment, you create two groups of liposomes in a solution containing 0.1 M NaCl—one made from red blood cell membranes and the other from frog egg cell membranes. When the liposomes are placed in water, those with red blood cell membranes burst more rapidly than those made from egg membranes. What could explain these results? Select True or False for each of the following statements. a. T/F The red blood cell liposomes are more hypertonic relative to water than the frog egg liposomes. b. T/F The red blood cell liposomes are more hypotonic relative to water than the frog egg liposomes. c. T/F The red blood cell liposomes contain more aquaporins than the frog egg liposomes. d. T/F The frog egg liposomes contain ion channels, which are not present in the red blood cell liposomes.

Examine the experimental chamber in Figure 6.8a. Explain what would occur by osmosis if you added a 1-M solution of sodium chloride on the left side and an equal volume of a 1.5 M solution of potassium ions on the right. How might the addition of the CFTR protein to the lipid bilayer impact the direction of water movement?