Mastering Biology Test #2 (Ch 7)
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+.
Drag the terms on the left to the appropriate blanks on the right to complete the sentences.
1. A phospholipid has a "head" made up of a glycerol molecule attached to a single phosphate group, which is attached to another small molecule. 2. Phospholipids vary in the small molecules attached to the phosphate group. The phospholipid shown in the figure has a choline group attached to phosphate. 3. Because the phosphate group and its attachments are either charged or polar, the phospholipid head is hydrophilic, which means it has an affinity for water. 4. A phospholipid also has two "tails" made up of two fatty acid molecules, which consist of a carboxyl group with a long hydrocarbon chain attached. 5. Because the C-H bonds in the fatty acid tails are relatively nonpolar, the phospholipid tails are hydrophobic, which means they are excluded from water.
Which of these can RAPIDLY pass directly through the phospholipids of the plasma membrane, without the help of a transport protein
A
Which of the following factors would tend to increase membrane fluidity?
A greater proportion of unsaturated phospholipids
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.
Active and passive transport of solutes across a membrane typically differ in which of the following ways? S
Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.
What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?
Amphipathic nature
Which of the following statements is TRUE with regard to this animation?
Both sodium and potassium ions are transported against their concentration gradients.
In what way do membranes vary among eukaryotic cells?
Certain proteins are unique to each membrane.
Which of the following correctly describes some aspect of exocytosis or endocytosis?
Exocytosis and endocytosis temporarily change the surface area of the plasma membrane.
If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?
Hypotonic
How can a lipid be distinguished from a sugar?
Lipids are mostly nonpolar.
What name is given to the process by which water crosses a selectively permeable membrane?
Osmosis
Select the correct statement about osmosis.
Osmosis is the diffusion of water molecules across a selectively permeable membrane.
Which of the following particles could diffuse easily through a cell membrane?
Oxygen (O2)
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.
Screenshot**
True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.
T
Which statement is correct?
The contents of a red blood cell are hyperosmotic to distilled water.
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.
Which of the following factors does not affect membrane permeability?
The polarity of membrane phospholipids
Which of the following statements about osmosis is correct?
The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.
Which factors affect the rate of osmotic movement of water?
The rate of osmosis increases with increasing differences in solute concentrations between two solutions separated by a selectively permeable membrane.
Which of the following statements about a typical plasma membrane is correct?
The two sides of the plasma membrane have different lipid and protein composition.
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 facilitated diffusion, what is the role of the transport protein?
Transport proteins provide a hydrophilic route for the solute to cross the membrane.
True or false? Osmosis is a type of diffusion.
True (Osmosis is the diffusion of water across a selectively permeable membrane.)
Which of the following best describes the structure of a biological membrane?
Two layers of phospholipids with proteins either crossing the layers or on the surface of the layers
What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium?
Water molecules move between the two solutions, but there is no net movement of water across the membrane.
Which of the following molecular movements is due to diffusion or osmosis?
When a plant cell is placed in concentrated salt water, water moves out of the cell. Submit
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
If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol?
active transport
The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following
cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis
Which of the following is least likely to be important in holding the components of a biological membrane together?
covalent interactions between the phospholipid and protein components of the membrane
Based on Figure 7.18 in your textbook, which of these experimental treatments would increase the rate of sucrose transport into the cell?
decreasing extracellular pH
According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly
embedded in a lipid bilayer.
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
Identify Structure A.
glycoprotein
Endocytosis moves materials _____ a cell via _____.
into ... membranous vesicles
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.
lipids carbon dioxide oxygen water
Facilitated diffusion is a type of _______.
passive transport
Which of the following processes includes all others?
passive transport
A white blood cell engulfing a bacterium is an example of _____.
phagocytosis
Identify Structure D.
phospholipid bilayer of membrane
What is the function of Structure E?
stabilization of the phospholipids
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
The permeability of a biological membrane to a specific polar solute depends primarily on which of the following?
the types of transport proteins in the membrane
Structure A in the figure is a(n) _____.
transport protein
