6. The Membrane

A selectively permeable membrane separates two solutions. Water is able to pass through this membrane; however, sucrose (a disaccharide) and glucose (a monosaccharide) cannot pass. The membrane separates a 0.2-molar sucrose solution from a 0.2-molar glucose solution. With time, how will the solutions change?

The internal solute concentration of a plant cell is about 0.8 M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?

A single plant cell is placed in an isotonic solution. Salt is then added to the solution. Which of the following would occur as a result of the salt addition?

Seawater is hypertonic to cytoplasm in vertebrate cells and in plant cells. If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?

The concentration of solutes in a red blood cell is about 2%, but red blood cells contain almost no sucrose or urea. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions?

Green olives may be preserved in brine, which is a 30% salt solution. How does this method of preservation prevent microorganisms from growing in the olives?

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.

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

A plant cell placed in distilled water will ______________; an animal cell placed in distilled water will ______________. a. burst … burst b. become flaccid . . . shrivel c. become turgid . . . be normal in shape d. become turgid . . . burst

The sodium concentration in a cell is 10 times less than the concentration in the surrounding fluid. How can the cell move sodium out of the cell? (Explain your answer.) a. passive transport b. receptor-mediated endocytosis c. active transport d. facilitated diffusion

DRAW IT An artificial 'cell' consisting of an aqueous solution enclosed in a selectively permeable membrane is immersed in a beaker containing a different solution, the 'environment,' as shown in the accompanying diagram. The membrane is permeable to water and to the simple sugars glucose and fructose but impermeable to the disaccharide sucrose. a. Draw solid arrows to indicate the net movement of solutes into and/or out of the cell. b. Is the solution outside the cell isotonic, hypotonic, or hypertonic? c. Draw a dashed arrow to show the net osmosis, if any. d. Will the artificial cell become more flaccid, more turgid, or stay the same? e. Eventually, will the two solutions have the same or different solute concentrations?

A cell that is placed in salty seawater will                   . a. take sodium and chloride ions in by diffusion; b. move water out of the cell by active transport; c. use facilitated diffusion to break apart the sodium and chloride ions; d. lose water to the outside of the cell via osmosis

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?