Chapter 7

Which of the following statements about the conditions shown in the U-shaped tube are true? A. There is less free water in the right arm of the tube than in the left arm of the tube. B. Water is tightly clustered around the hydrophilic solute molecules on both sides of the membrane. C. There is more solute in the left arm of the tube than in the right arm of the tube. D. Solutes can pass through the selectively permeable membrane from right to left, but free water cannot.

A. There is less free water in the right arm of the tube than in the left arm of the tube. B. Water is tightly clustered around the hydrophilic solute molecules on both sides of the membrane.

In this diagram of the plasma membranes of two adjoining cells, identify the protein indicated by the white arrow, including its function. A. a receptor protein that binds with a signaling molecule and relays the message into the cell by activating other molecules inside the cell B. an active transport protein that moves molecules across a membrane against their concentration gradient C. a glycoprotein that is involved in cell-cell recognition D. a protein involved in enzymatic activity E. an attachment protein that provides structural support

A. a receptor protein that binds with a signaling molecule and relays the message into the cell by activating other molecules inside the cell

If the pores in the selectively permeable membrane became larger, but still not large enough to let the sugar pass through, what would happen during osmosis in the U-shaped tube compared to what is shown in the figure? A. There would be less free water on the left side of the tube, so the water level on the right would not get as high. B. The final water levels would be the same as shown in the figure, but the solutions would reach near equal concentrations faster. C. Some water would be pushed back to the left side through the larger pores, so the water level on the right would not get as high. D. More water could pass to the right side of the tube so the water level would rise even higher.

B. The final water levels would be the same as shown in the figure, but the solutions would reach near equal concentrations faster.

Biologists use the fluid mosaic model to describe membrane structure. Which statements about the fluid mosaic structure of a membrane are correct? Select the three correct statements. A. Membranes include a mosaic, or mix, of carbohydrates embedded in a phospholipid bilayer. B. The kinky tails of some proteins help keep the membrane fluid by preventing the component molecules from packing solidly together. C. The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center. D. Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane. E. The diverse proteins found in and attached to membranes perform many important functions.

C. The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center. D. Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane. E. The diverse proteins found in and attached to membranes perform many important functions.

If more sugar were added to the solution on the left side of the tube, what would happen to the water level on the right side of the tube? A. The water level would stay the same. B. The water level would rise. C. The water level would go down.

C. The water level would go down.

You are working on a team that is designing a new drug. For this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would be a factor that determines whether the molecule selectively enters the target cells? A. the phospholipid composition of the target cells' plasma membrane B. the nonpolar, hydrophobic nature of the drug molecule C. the concentration of the drug molecule that is transported in the blood D. the similarity of the drug molecule to other molecules that are transported into the target cells

D. the similarity of the drug molecule to other molecules that are transported into the target cells

During osmosis, water diffuses across a selectively permeable membrane from the region of higher _________________ concentration and lower _______________ concentration to the side with lower _________________ concentration and higher ___________________ concentration.

free water, solute, free water, solute