Cell Membrane Homework Mastering Biology

Drag the labels onto the table to indicate when each statement is true. Labels can be used once, more than once, or not at all.

-Orange dye moves independently of purple dye ALWAYS -Concentration gradients exist that drive diffusion of both dyes ONLY BEFORE EQUILIBRIUM IS REACHED -There is net movement of orange dye from side A to side B ONLY BEFORE EQUILIBRIUM IS REACHED -Purple dye moves only from side B to side A NEVER There is no net movement of purple dye ONLY AT EQUILIBRIUM

Which of the following statements correctly describe(s) the driving forces for diffusion of Na+ and K+ ions through their respective channels? Select all that apply.

-The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane. -The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane. -The electrochemical gradient is larger for Na+ than for K+.

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. -Membranes include a mosaic, or mix, of carbohydrates embedded in a phospholipid bilayer. -The diverse proteins found in and attached to membranes perform many important functions. -The kinky tails of some proteins help keep the membrane fluid by preventing the component molecules from packing solidly together. -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. -Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane.

-The diverse proteins found in and attached to membranes perform many important functions. -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. -Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane.

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

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

Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply.

-carbon dioxide -lipids -water -oxygen

Which of these can RAPIDLY pass directly through the phospholipids of the plasma membrane, without the help of a transport protein?

A only

Drag the terms on the left to the appropriate blanks on the right to complete the sentence. Terms may be used more than once.

During osmosis, water diffuses across a selectively permeable membrane from the region of higher FREE WATER concentration and lower SOLUTE concentration to the side with lower FREE WATER concentration and higher SOLUTE concentration.

Which of the following statements best describes a characteristic feature of diffusion?

It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers.

ONLY CHANNELS -allow water molecules and small ions to flow quickly across the membrane. -provide a continuous path across the membrane. ONLY CARRIERS -transport primarily small polar organic molecules. -undergo a change in shape to transport solutes across the membrane. BOTH CHANNELS AND CARRIERS -transport solutes down a concentration or electrochemical gradient. -are integral membrane proteins. -provide a hydrophilic path across the membrane.

Which of the following results is most likely result if a portion of an animal's blood is replaced with distilled water?

The animal's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.

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?

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

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?

The water level would go down.

In this diagram of the plasma membranes of two adjoining cells, identify the protein indicated by the white arrow, including its function.

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

Endocytosis moves materials _____ a cell via _____.

into ... membranous vesicles

A white blood cell engulfing a bacterium is an example of _____.

phagocytosis

You can recognize the process of pinocytosis when _____.

the cell is engulfing extracellular fluid

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?

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

Structure A in the figure is a(n) _____.

transport protein