Chapter 7 Membrane Structure And Function Flashcards
Red blood cells contain a 2% concentration of solutes. A red blood cell is placed into a solution that contained 4% concentration of solutes to which the cell is not permeable. What will happen to the red blood cell?
The cell will decrease in size as water flows out of it.
Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?
Phospholipids form a selectively permeable structure.
Which of the following is a correct difference between active transport and facilitated diffusion?
Active transport requires energy from ATP, and facilitated diffusion does not.
Which of the following statements about passive transport is correct?
Passive transport permits the solute to move in either direction, but the net movement of the population of solute molecules occurs down the concentration gradient of the molecule.
Which of the following is correct regarding peripheral proteins?
These proteins are found only on the surface of the plasma membrane.
If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?
Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall.
The plasma membrane exhibits selective permeability. This means that __________________.
The plasma membrane allows some substances to flow through it more easily than others.
Which of the following molecules is most likely to passively diffuse across the plasma membrane?
Carbon dioxide
Which of these statements describes some aspects of facilitated diffusion?
Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane.
The sodium-potassium pump _______________.
Transports sodium ions out of the cell and transports potassium ions into the cell.
Which of the following is correct regarding integral proteins?
These proteins exhibit both hydrophilic and hydrophobic properties.
A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution?
The solution is hypertonic.
Which of the following substances would be most likely to pass through the plasma membrane without the help of a transport protein?
A non-polar molecule, such as a hydrocarbon.
How does cholesterol affect membrane fluidity?
At body temperature, it makes the membrane less fluid.
Which of the following a structural arrangements of the components in biological membranes facilitates the cell membrane’s property of selective permeability?
Proteins embedded in two layers of phospholipids.
In facilitated diffusion, _______________ proteins provide openings in the plasma membrane for substances to flow through without changing structure, and ________________ proteins allow passage of substances through the plasma membrane after undergoing a subtle change in shape.
Channel; carrier
Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active than cell B; cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more rapidly into cell __________________ because ___________________.
B; The diffusion gradient in cell B is steeper.
Which of the following would be least likely to diffuse through a plasma membrane without the help of a transport protein?
A large non-polar molecule.
Which of the following statements concerning carbohydrates associated with the plasma membrane is correct?
Membrane carbohydrates function primarily in cell-cell recognition.
Why is energy required for active transport?
Because it moves solutes against their concentration gradient.
How does the “fluid mosaic model” describe the structure of the plasma membrane?
Proteins in the membrane contribute to the mosaic quality of the membrane while the lateral and rotational movements of phospholipids contribute to its fluidity.
Which of the following molecules are most abundant in the plasma membrane?
Phospholipids
Which of the following plant cells would exhibit the most turn or pressure?
A plant placed in a hypotonic solution.
Which of the following processes and organelle(s) accounts for the replacement of lipids lost from the plasma membrane?
Exocytosis and smooth and rough ER
Which of the following statements about diffusion is true?
It is a passive process
What function do carbohydrates fulfill in the plasma membrane?
Cell-Cell recognition
All cells have voltage across their membranes. This voltage is called a(n) _________________ and is often maintained by ________________.
Membrane potential; Electrogenic pumps
Which of the following cell structures exhibits selective permeability between a cell and its external environment?
Plasma membrane
A nursing infant is able to obtain disease fighting antibodies, which are large protein molecules, from it’s mothers milk. These molecules probably enter the cells lining the baby’s digestive tract via which processes?
Endocytosis
The internal solute concentration of a plant cell is about 0.8M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution
1.0M
What best describes a characteristic feature of integral membrane proteins?
They are amphipathic, with at least one hydrophobic region
Which of the following factors would tend to increase membrane fluidity?
A greater portion of unsaturated phospholipids
Which of the following statements best describes a characteristic of biological membranes?
Phospholipids move laterally within the plane of the membrane.
Which of the following types of molecules are most likely to be excluded from the hydrophobic portion of the phospholipid belayer?
Peripheral membrane proteins
In what way do the membranes of eukaryotic cell vary?
Certain proteins are unique to each membrane.
Which of the following statements best describes how unsaturated fatty acids increase membrane fluidity at lower temperatures?
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
The permeability of a biological membrane to a specific polar solute may depend on which of the following?
The type of transport proteins in the membrane
What type of molecule will diffuse through a cell membrane most readily?
Small hydrophobic molecules
Which of the following types of molecules are least likely to diffuse through the phospholipid belayer of a cell membrane?
Small ions
Which of the following statements best describes a characteristic feature of a carrier protein in a plasma membrane?
It exhibits specificity for a particular type of molecule.
Which of the following molecules would likely diffuse through the lipid belayer of a plasma membrane most rapidly?
O2
A defect in which of the following molecules would dramatically reduce the rate of diffusion of water across cell membranes?
Aquaporins
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.
When the interior of a cell is U.N. equilibrium with its environment, which of the following statements best describes the relative movement of molecules that can diffuse through the plasma membrane?
All movement of molecules across the plasma membrane occurs by active transport.
Which of the following statements best describes a characteristic feature of osmosis?
In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.
Celery stalks that are immersed in forest water for several hours become stiff. What best explains the observation that similar stalks left in a 0.15 M salt solution become limp?
The freshwater is hypotonic and the salt solution is hypertonic to the cells of the celery stalks.
What will happen to a red blood cell which as an internal ion content of about 0.9%, if placed into a beaker of pure water?
The cell will swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC.
Which of the following statements best describes the normal toxicity conditions for typical plant and animal cells in their native environments?
The animal cell is in an isotonic solution, and the plant cell is in a hypertonic solution.
Which of the following results is most likely when a plant cell is submerged in a hypertonic solution?
Plasmolysis will shrink the interior of the cell.
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 statements best describes characteristic activities of a sodium-potassium pump?
The pump moves three sodium ions out of a cell and two potassium ions into a cell using energy from ATP hydrolysis.
Which of the following statements best explained why the sodium-potassium pump is an electro genie pump?
It generates voltage across the membrane.
Which of the following membrane activities requires energy from ATP hydrolysis?
Movement of Na+ ions from a low3er concentration in a mammalian cell to a high concentration in the extracellular fluid.
The voltage across a membrane is called the ___________________________.
Membrane potential
Diffusion of ions actors membranes through specific ion channels is driven by ________________________.
Ion electrochemical gradients
The phosphate transport system in bacteria import phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Because phosphate import depends on a pH gradient across the membrane, phosphate transport is most likely an example of which of the following transport processes?
Cotransport
The force driving simple diffusion is _____________, while the energy source for active transport is ___________________.
A concentration gradient; ATP hydrolysis
Which of the following processes is used by white blood cells when engulfing bacteria?
Phagocytosis
Which of the following statements best describes the difference between pinocytosis and receptor-mediated endocytosis?
Pinocytosis is non-selective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.
In receptor-mediated endocytosis, membrane receptors bind to molecules upside of the cell. Immediately following endocytosis where will the membrane receptors be located?
On the inside surface of the vesicle
Which of the following organelles plays a primary role in the digestion of bacteria engulfed by WBCs?
Lysosomes
Which of the following statements best describes metabolism in its entirety in all organisms?
Metabolism consists of all the energy transformation reactions in an organism.
Which of the following examples describes a type. Of potential rather than kinetic energy?
A sucrose molecule
Which of the following terms most percisely identifies the cellular process of breaking down large molecules into smaller ones?
Catabolism (catabolic pathways)
What is the first law of thermodynamics?
Energy cannot be created or destroyed
A decrease in entropy is associated with which of the following types of reactions?
Dehydration
