Chapter 7 biology mastering
The permeability of a biological membrane to a specific polar solute depends primarily on which of the following? -The amount of cholesterol in the membrane -the types of transport proteins in the membrane -the phospholipid composition of the membrane -the presence of unsaturated fatty acids in the membrane -the types of polysaccharides present in the membrane
the types of transport proteins in the membrane
The permeability of a biological membrane to a specific polar solute may depend on which of the following? a. the amount of cholesterol in the membrane b. the types of transport proteins in the membrane c.the phospholipid composition of the membrane d. the presence of unsaturated fatty acids in the membrane e. the types of polysaccharides present in the membrane
the types of transport proteins in the membrane
Structure A in the figure is a(n) _____. a. receptor molecule b. structural protein c. transport protein d. antibody e. enzyme
transport protein
What is the purple round thing? a. solute b. transport protein c. phospholipid d. solvent e. water molecules
transport protein
Polar molecules (water, sugars): transport protein required? transport protein required?
transport protein required to cross efficently
Ions ( Na+, K+, Ca2+, Cl-): transport protein required
transport protein required to cross efficiently
Which of the following best describes the structure of a biological membrane? a. two layers of phospholipids with proteins either crossing the layers or on the surface of the layers b. two layers of phospholipids with proteins embedded between the two layers c. a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot d. two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins e. a fluid structure in which phospholipids and proteins move freely between sides of the membrane
two layers of phospholipids with proteins either crossing the layers or on the surface of the layers
The membranes of winter wheat are able to remain fluid when it is extremely cold by ________. -increasing the proportion of unsaturated phospholipids in the membrane -decreasing the percentage of cholesterol molecules in the membrane -decreasing the number of hydrophobic proteins in the membrane -increasing the proportion of glycolipids in the membrane
increasing the proportion of unsaturated phospholipids in the membrane
When molecules move down their concentration gradient, they move from where they are ___________ to where they are_____________
more concentrated; less concentrated
Which of the following membrane activities requires energy from ATP hydrolysis? -movement of carbon dioxide out of a paramecium -movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell -facilitated diffusion of chloride ions across the membrane through a chloride channel -movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid
movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid
In what way do the membranes of a eukaryotic cell vary? -Certain proteins are unique to each membrane. -Only certain membranes of the cell are selectively permeable. -Phospholipids are found only in certain membranes. -Some membranes have hydrophobic surfaces exposed to the cytoplasm, while others have hydrophilic surfaces facing the cytoplasm.
-Certain proteins are unique to each membrane.
Identify Structure A a. Cholesterol b. extracellular matrix c. glycoprotein d. phospholipid e. protein
glycoprotein
Ions ( Na+, K+, Ca2+, Cl-): able to cross lipid bilayer
have difficulty crossing the hydrophobic part
Polar molecules (water, sugars): able to cross lipid bilayer?
have difficulty crossing the hydrophobic part
Ions ( Na+, K+, Ca2+, Cl-): hydrophobic or hydrophilic
hydrophilic
Polar molecules (water, sugars): hydrophobic or hydrophilic
hydrophilic
Nonpolar molecules (hydrocarbons, O2, CO2) Hydrophobic or Hydrophilic?
hydrophobic
Phospholipids vary in the small molecules attached to the phosphate group. The phospholipid shown in the figure has a _______ attached to phosphate.
Choline group
Which of these cannot rapidly pass directly through the phospholipids of the plasma membrane? C only B, C, and D A only B only D only
B, C, and D
Which of the following statements is TRUE with regard to this animation? -Both sodium and potassium ions are transported against their concentration gradients. -Sodium ions are transported down their concentration gradient. -Potassium ions are transported down their concentration gradient. -The cell does not expend ATP. -The cell is not expending energy.
Both sodium and potassium ions are transported against their concentration gradients
A phospholipid has 2 "tails" made up of 2 _______molecules, which consists of a carboxly group with a long hydrocarbon chain attached.
Fatty Acid
because the phosphate group and its attachments are either charged or polar, the phospholipid head is ________which means it has an affinity for water.
Hydrophilic
Because the C-H bonds in the fatty acid tails are relatively non polar, the phospholipid tails are ______, which means they are excluded from water.
Hydrophobic
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? a.Hypotonic b. Hypertonic c. Osmotic d. Isotonic
Hypotonic
Which of the following statements describes a characteristic feature of a carrier protein in a plasma membrane? -It exhibits specificity for a particular type of molecule. -It has no hydrophobic regions. -It requires the expenditure of cellular energy to function. -It works against diffusion.
It exhibits specificity for a particular type of molecule.
How can a lipid be distinguished from a sugar? a. A lipid dissolves in water b. A lipid is made up of only hydrocarbons. c. Lipids are mostly nonpolar d. Lipids are mostly unsaturated
Lipids are mostly nonpolar.
Which of the following is a major difference between prokaryotic and eukaryotic cells? -Prokaryotic cells have no phospholipids; eukaryotic cells do. -Prokaryotic cells have no DNA; eukaryotic cells have DNA. -Most prokaryotic cells have no internal membranes; eukaryotic cells do. -Eukaryotic cells have a plasma membrane, whereas prokaryotic cells do not.
Most prokaryotic cells have no internal membranes; eukaryotic cells do.
Diffusion across a biological membrane is called
Passive Transport
A phospholipid bilayer with equal amounts of saturated and unsaturated fatty acids displays a specific permeability to glucose. What effect will increasing the proportion of unsaturated fatty acids in the bilayer have on the membrane's permeability to glucose? - Permeability to glucose will decrease. -Permeability will decrease initially then increase as the bilayer fills with glucose. -Permeability to glucose will increase -Permeability to glucose will stay the same.
Permeability to glucose will increase
A phospholipid has a "head" made up of a glycerol molecule attached to a single _________, which is attached to another small molecule.
Phosphate Group
Which of the following statements is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures? -The double bonds block interaction among the hydrophilic head groups of the lipids. -The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. -Unsaturated fatty acids have a higher cholesterol content, which prevents adjacent lipids from packing tightly. -Unsaturated fatty acids are more nonpolar than saturated fatty acids.
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
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? -More water could pass to the right side of the tube so the water level would rise even higher. -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. -The final water levels would be the same as shown in the figure, but the solutions would reach near equal concentrations faster. -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.
The final water levels would be the same as shown in the figure, but the solutions would reach near equal concentrations faster.
How do membrane phospholipids interact with water? -The polar heads interact with water; the nonpolar tails do not. -They have hydrophilic tails that face outward and are exposed to water and hydrophobic heads that face the center of the membrane and are shielded from water. -The polar heads repel water and the nonpolar tails attract water. -Phospholipids do not interact with water because they are lipids, and thus are hydrophobic
The polar heads interact with water; the nonpolar tails do not.
Which of the following factors does not affect membrane permeability? a. The saturation of hydrocarbon tails in membrane phospholipids b. The amount of cholesterol in the membrane c. The polarity of membrane phospholipids d. Temperature
The polarity of membrane phospholipids
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. -The water level would rise. -The water level would stay the same.
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. -Transport proteins organize the phospholipids to allow the solute to cross the membrane. -Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane. -Transport proteins provide the energy for diffusion of the solute. -Transport proteins provide a low-resistance channel for water molecules to cross the membrane.
Transport proteins provide a hydrophilic route for the solute to cross the membrane.
In facilitated diffusion, what is the role of the transport protein? See Concept 7.3 (Page 135) -Transport proteins organize the phospholipids to allow the solute to cross the membrane. -Transport proteins provide a hydrophilic route for the solute to cross the membrane. -Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane. -Transport proteins provide a low-resistance channel for water molecules to cross the membrane. -Transport proteins provide the energy for diffusion of the solute.
Transport proteins provide a hydrophilic route for the solute to cross the membrane.
True or false? Osmosis is a type of diffusion.
True
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.
True
Which of the following factors would tend to increase membrane fluidity? a. a relatively high protein content in the membrane b. a greater proportion of saturated phospholipids c. a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses d. a lower temperature e. a greater proportion of unsaturated phospholipids
a greater proportion of unsaturated phospholipids
What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium? a. Water molecules move between the two solutions, but there is no net movement of water across the membrane. b. Water molecules continue to move from the hypotonic solution to the hypertonic solution. c. Water molecules no longer move between the solutions.
a. Water molecules move between the two solutions, but there is no net movement of water across the membrane.
Facilitated diffusion is a type of _______. a. passive transport b. phagocytosis c. pinocytosis d. active transport
a. passive transport
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? a. passive transport b. diffusion c. active transport d. osmosis e. facilitated diffusion
active transport
Which of the following molecules dramatically increases the rate of diffusion of water across cell membranes? -ATP -gated ion channels -aquaporins -the sodium-potassium pump
aquaporins
According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly a. spread in a continuous layer over the inner and outer surfaces of the membrane. b. embedded in a lipid bilayer. c. confined to the hydrophobic interior of the membrane. d.free to depart from the fluid membrane and dissolve in the surrounding solution. e. randomly oriented in the membrane, with no fixed inside-outside polarity.
b. embedded in a lipid bilayer.
What property of dishwashing liquid (detergent) makes it useful to wash grease from pans? a. Hydrophobic nature b. Solubility in water c. Amphipathic nature d. Permeability
c. Amphipathic nature
Nonpolar molecules (hydrocarbons, O2, CO2) able to cross lipid bilayer
can cross easily
The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following? a. cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis b. passive diffusion of the glucose through the lipid bilayer c. facilitated diffusion of the glucose using a carrier protein d. movement of glucose into the cell through a glucose channel e. receptor-mediated endocytosis
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? a. hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane b. hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane c. polar interactions among the phospholipid head groups on the same surface of the membrane d. covalent interactions between the phospholipid and protein components of the membrane e. hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane
covalent interactions between the phospholipid and protein components of the membrane
Which of the following particles could diffuse easily through a cell membrane? a. Hydrogen ion (H+) b. Sodium ion (Na+) c. Glucose d. Oxygen (O2)
d. Oxygen (O2)
A sodium-potassium pump ________. -move three sodium ions out of a cell and two potassium ions into a cell and generates an ATP in each cycle -moves three sodium ions out of a cell and two potassium ions into a cell using energy from ATP hydrolysis -moves three potassium ions out of a cell and two sodium ions into a cell using energy from ATP hydrolysis -moves three potassium ions out of a cell and two sodium ions into a cell while producing ATP for each cycle
moves three sodium ions out of a cell and two potassium ions into a cell using energy from ATP hydrolysis
Nonpolar molecules (hydrocarbons, O2, CO2) transport protein required?
no transport protein required
Hydrophobic substances like salad oil are -nonpolar molecules that repel water molecules. -nonpolar molecules that have an affinity for water because they contain many hydrogens that can form hydrogen bonds with water. -polar molecules that repel water molecules. -polar molecules that have an affinity for water because they contain many hydrogens that can form hydrogen bonds with water.
nonpolar molecules that repel water molecules.
Which of the following processes includes all of the others? -transport of an ion down its electrochemical gradient -facilitated diffusion -passive transport -osmosis
passive transport
Identify Structure D a. extracellular matrix b. glycoprotein c. cholesterol d. protein e. phospholipid bilayer of membrane
phospholipid bilayer of membrane
What kinds of molecules pass through a cell membrane most easily? large polar small and ionic small and hydrophobic large and hydrophobic
small and hydrophobic
Which of the following are least likely to diffuse through the phospholipid bilayer of a cell membrane? small ions carbon dioxide small hydrophobic molecules large hydrophobic molecules
small ions
What are the triangles in the facilitated diffusion? a. solute b. water molecule c. phospholipid d. solvent e. transport protein
solute
What is the function of Structure E? a. stabilization of the phospholipids b. cell-cell communication c. structural support of the cell d. detection of environmental change e. transport across the plasma membrane
stabilization of the phospholipids
Which of the following best describes the structure of a biological membrane? -a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot -two layers of phospholipids with proteins either crossing the layers or on the surface of the layers -two layers of phospholipids with proteins embedded between the two layers -two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins -a fluid structure in which phospholipids and proteins move freely between sides of the membrane
two layers of phospholipids with proteins either crossing the layers or on the surface of the layers
