Exam 7: Membrane Structure and Function

What will happen to a red blood cell (RBC), which has an internal ion content of about 0.9%, if it is placed into a beaker of pure water?

The solutions in the two arms of this U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal. Which of the following will be true when the system illustrated above reaches equilibrium?

Why are lipids and proteins free to move laterally in membranes?

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same. At the beginning of the U-tube experiment illustrated above, which of the following statements is true?

Which of the following statements is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?

The phosphate transport system in bacteria imports phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Phosphate import depends on a pH gradient across the membrane-more acidic outside the cell than inside the cell. In this bacterial cell, phosphate transport is an example of ________.

What kinds of molecules pass through a cell membrane most easily?

Five dialysis bags, constructed of a type of membrane that is permeable to water and impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed), and the percent change in mass of each bag was graphed. Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment?

In what way do the membranes of a eukaryotic cell vary?

Which of the following would likely diffuse through the lipid bilayer of a plasma membrane most rapidly?

For the following questions, match the labeled component of the cell membrane in the figure with its description. - Which component in the accompanying figure is cholesterol? A) B B) C C) D D) E

An organism with a cell wall would most likely be unable to take in materials through ________.

In some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two proton pumps present in the membrane. The gradients of the other ions are most likely accounted for by ________.

Diffusion of ions across membranes through specific ion channels is driven by ________.

Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this fact most probably mean?

Based on Figure 7.18, which of these experimental treatments would increase the rate of sucrose transport into a plant cell?

Three lab groups carried out an experiment to identify the concentration of sucrose in six solutions. Each unknown contained one of the following sucrose concentrations: 0.0 M, 0.2 M, 0.4 M, 0.6 M, 0.8 M, and -1.0 M. Cubes of sweet potato (1 cm³) were soaked for 24 hours in each solution and weighed to determine the change in mass. Each data entry represents the average of three sample replicates expressed as percent change in mass following a 24-hour soak in the unknown solutions. From the data given, which statement most accurately describes what is occurring in response to a particular unknown solution?

For the following questions, match the labeled component of the cell membrane in the figure with its description. - Which component in the accompanying figure is a microfilament (actin filament) of the cytoskeleton? A) A B) B C) C D) D

Several epidemic microbial diseases of earlier centuries incurred high death rates because they resulted in severe dehydration due to vomiting and diarrhea. Today they are usually not fatal because we have developed which of the following types of treatments?

The force driving simple diffusion is ________, while the energy source for active transport is ________.