
Koeppen: Berne and Levy Physiology, 7th Edition
Chapter 01: Principles of Cell Function
Multiple Choice Questions and Answers
1. The subcellular structure that degrades proteins is called the:
A. Tight junction
B. Mitochondria
C. Lysosome
D. Plasma membrane
E. Ribosome
ANS: C
2. An experiment is done to measure the uptake of an amino acid into a cell. The following data are obtained:
If Na+ is removed from the extracellular bathing solution, or if a drug is added that prevents the cell from making adenosine triphosphate (ATP), the uptake of amino acid into the cell is markedly reduced. According to this information, which of the following mechanisms is probably responsible for the transport of the amino acid into the cell?
A. Passive diffusion through the lipid bilayer
B. Uniporter
C. Transport ATPase
D. Na+ symporter
E. Na+ antiporter
ANS: D
3. A membrane permeable by only Na+ separates two compartments containing Na2SO4, shown as follows:
Electrodes are placed in both compartments, and a voltage is applied (that of compartment A is held at 0 mV). What voltage applied to compartment B would result in no net movement of Na+ across the membrane separating the compartments?
A. –60 mV
B. –30 mV
C. 0 mV
D. +30 mV
E. +60 mV
ANS: E
4. The resting membrane potential of a cell is –85 mV. The intracellular and extracellular concentrations of several ions are indicated in the following table, as is the calculated Nernst equilibrium potential (Ei) for each of these ions:
Ion |
Concentration Inside Cell |
Concentration Outside Cell |
Ei |
Na+ |
12 mEq/L |
145 mEq/L |
66 mV |
K+ |
150 mEq/L |
4 mEq/L |
–96 mV |
Cl– |
30 mEq/L |
105 mEq/L |
–33 mV |
Ca++ |
0.0001 mmol/dL |
1 mmol/dL |
122 mV |
The membrane has channels for Na+, K+, Cl–, and Ca++. The conductance of the membrane is the greatest for which ion?
A. Na+
B. K+
C. Cl–
D. Ca++
ANS: B
5. A cell contains the following membrane transporters:
Na+ channel
K+ channel
Na+,K+-ATPase
The resting membrane voltage of the cell is –80 mV, and the intracellular and extracellular ion concentrations are as follows:
Ion |
Intracellular Concentration |
Extracellular Concentration |
Na+ |
10 mEq/L |
145 mEq/L |
K+ |
120 mEq/L |
4 mEq/L |
The cell is treated with a drug to inhibit the Na+,K+-ATPase. What would be the effect of this drug on the following parameters?
|
Intracellular [Na+] |
Intracellular [K+] |
Cell Volume |
Membrane Voltage |
A. |
Decrease |
Decrease |
Decrease |
Depolarize |
B. |
Increase |
Decrease |
Increase |
Depolarize |
C. |
Increase |
Increase |
Increase |
No change |
D. |
Decrease |
Increase |
Decrease |
Hyperpolarize |
E. |
Increase |
Increase |
Decrease |
Hyperpolarize |
ANS: B
6. Which of the labeled proteins (shaded) is attached to the membrane by a glycosylphosphatidylinositol (GPI) anchor?
ANS: E
7. A cell has channels for Na+, K+, and Cl– in its plasma membrane. The resting membrane potential is –60 mV (cell interior negative). The intracellular and extracellular concentrations for these ions, as well as the calculated Nernst potentials, are listed as follows:
Ion |
Intracellular Concentration |
Extracellular Concentration |
Ei |
Na+ |
14 mEq/L |
140 mEq/L |
60 mV |
K+ |
150 mEq/L |
5 mEq/L |
–89 mV |
Cl– |
10 mEq/L |
100 mEq/L |
–60 mV |
A drug is applied to the cell that increases the permeability of the cell by Cl– (i.e., it opens Cl– channels). What effect will this drug have on the net movement of Cl– across the plasma membrane?
A. Net Cl– movement out of the cell will be increased.
B. Net Cl– movement into the cell will be increased.
C. There will be no change in the net movement of Cl–.
ANS: C
8. Reducing the extracellular [K+] would be expected to have which of the following effects on the resting membrane potential and on the excitability of ventricular myocytes?
|
Membrane Potential |
Excitability |
A. |
Unchanged |
Unchanged |
B. |
Hyperpolarized |
Decreased |
C. |
Hyperpolarized |
Increased |
D. |
Depolarized |
Decreased |
E. |
Depolarized |
Increased |
ANS: B
9. A cell is bathed in an isotonic NaCl solution that contains 5 mmol/L of glucose. The intracellular concentration of glucose is 10 mmol/L. What is the most likely mechanism for the transport of glucose across the plasma membrane into this cell?
A. Glucose uniporter
B. Na+-glucose symporter
C. Na+-glucose antiporter
D. Diffusion of glucose through the lipid bilayer of the membrane
ANS: B
10. A blood sample is taken from an individual whose blood osmolality is 295 mOsm per kilogram of water. Red blood cells from this sample are then placed in the following solutions:
Solution |
Osmolality (mOsm/kg H2O) |
Reflection Coefficient (s) of Solute |
1. NaCl |
300 |
1 |
2. Fructose |
300 |
0.5 |
3. Urea |
300 |
0 |
4. CaCl2 |
100 |
1 |
5. KCl |
150 |
1 |
The red blood cells in which of these solutions will swell to the greatest degree?
A. 1
B. 2
C. 3
D. 4
E. 5
ANS: C
11. A solution that causes a cell to shrink is:
A. Isotonic
B. Hypotonic
C. Hypertonic
ANS: C
12. Osmosis is:
A. The active transport of water
B. The number of solute particles in 1 kg of water
C. The diffusion of water across cell membranes
D. The defined as the weight of a volume of a solution divided by the weight of an equivalent volume of distilled water
E. The amount of a substance relative to its molecular weight
ANS: C
More Questions and Answers from Berne & Levy Physiology
What separates the intracellular contents from the extracellular environment?
Plasma membrane
How are eukaryotic cells distinguished from prokaryotic cells?
Presence of membrane-delimited nucleus in eukaryotic cells
Name Important cellular functions of plasma membrane (6)
- Selective transport (carried out by membrane transport proteins)
- Cell recognition (through cell surface antigens)
- Cell communication (through neurotransmitter and hormone receptors and through signal transduction pathways)
- Tissue organization
- Membrane-dependent enzymatic activity
- Determination of cell shape by linkage of cytoskeleton to the plasma membrane
What are the Examples of cells within the human body without nucleus?
Mature human red blood cells and cells within the lens of the eye
An aqueous solution containing numerous organic molecules, ions, cytoskeletal elements, and a number of organelles
Cytoplasm
The plasma membrane of eukaryotic cells consists of a...
5-nm-thick lipid bilayer with associated proteins
7. Primary function of cytosol: Metabolism, protein synthesis (free ribosomes)
8. Primary function of cytoskeleton: Cell shape and movement, intracellular transport
9. Primary function of nucleus: Genome (22 autosomes and 2 sex chromo- somes), DNA and RNA synthesis
10. Primary function of mitochondria: ATP synthesis by oxidative phosphoryla- tion, calcium storage
11. Primary function of smooth endoplasmic reticulum: Synthesis of lipids, cal- cium storage
12. Primary function of free ribosomes: Translation of mRNA into cytosolic pro- teins
13. Primary function of Rough endoplasmic reticulum: Translation of mRNA into membrane associated proteins or for secretion out of the cell
14. Primary function of lysosome: Intracellular degradation
15. Primary function of endosome: Cellular uptake of cholesterol, removal of receptors from the plasma membrane, uptake of small molecules and water into the cell, internalization of large particles (e.g., bacteria, cell debris)
16. Primary function of golgi apparatus: Modification, sorting, and packaging of proteins and lipids for delivery to other organelles within the cell or for secretion out of the cell
17. Primary function of proteosome: Degradation of intracellular proteins
18. Primary function of peroxisome: Detoxification of substance
19. Major lipids of the plasma membrane: Phospholipids and phosphoglycerides
20. Amphipathic molecules that contain a charged (or polar) hydrophilic head and two (nonpolar) hydrophobic fatty acyl chains: Phospholipids
21. The amphipathic nature of phospholipid molecule is critical for...: The formation of bilayer
22. The form the core of the bilayer, and the are exposed on the surface: hydrophobic fatty acyl chains, polar head groups
23. The presence of a produces a "kink" in the fatty acyl chain, which prevents tight packing of membrane lipids and increases membrane fluidity.: Double bond
24. The majority of membrane phospholipids have a "backbone" to which are attached the , and an is linked to via a .: Glycerol, fatty acyl chains, alcohol, glycerol, phosphate group
25. Common alcohols: Choline, ethanolamine, serine, inositol, and glycerol
26. Another important phospholipid which has the amino alcohol sphingosine as its "backbone" instead of glycerol: Sphingomyelin
27. Usual length of fatty acyl chains: 14 to 20 carbons, may be saturated or unsaturated (i.e., contain one or more double bonds)
28. 5 common phospholipids: OUTER LEAFLET:
- Phosphatidylcholine
- Shingomyelin
INNER LEAFLET:
- Phosphatidylethanolamine
- Phosphatidylserine
- Phosphatidylinositol (involved in signal transduction)
29. Found in both leaflets and serves to stabilize the membrane at normal body temperature (37 degrees C): Cholesterol
30. Minor lipid component of the plasma membrane: Glycolipids
31. Consist of two fatty acyl chains linked to polar head groups that consist of carbohydrates: Glycolipids
32. A glycolipid that plays an important role in anchoring proteins to the outer leaflet of the membrane: Glycosylphosphatylinositol (GPI)
33. True or False: Both cholesterol and glycolipids, like the phospholipids, are amphipathic.: True
34. As temperature increases, the fluidity of the membrane .: In- creases
35. The presence of unsaturated fatty acyl chains in the phospholipids and glycolipids (increases/decreases) membrane fluidity.: Increases
36. True or False: Although the lipid bilayer is "fluid," movement of proteins in the membrane can be constrained or limited.: True. For example, membrane proteins can be anchored to components of the intracellular cytoskeleton, which limits their movement.
37. Describe the plasma membrane of epithelial cells.: Junctional complexes (e.g., tight junctions) separate the plasma membrane of epithelial cells into two domains: apical and basolateral
38. Crucial for functioning of several organ systems (e.g., the gastrointestinal tract and kidneys): Vectorial transport
39. One important function is to segregate signaling molecules.: Lipid rafts
40. Classifications of membrane proteins: Integral, lipid-anchored, peripheral
41. Embedded in the lipid bilayer, where hydrophobic amino acid residues are associated with the hydrophobic fatty acyl chains of the membrane lipids.: - Integral membrane proteins
42. Integral membrane proteins that span the bilayer: Transmembrane proteins
43. Transmembrane proteins have both hydrophobic and hydrophilic regions. The hydrophobic region, often in the form of , spans the mem- brane. Hydrophilic amino acid residues are then exposed to the aqueous environment on either side of the membrane.: Alpha helix
44. A superfamily of membrane proteins that serve as receptors for many hor- mones, neurotransmitters, and numerous drugs.: G protein-coupled receptors
45. G protein-coupled receptors are coupled to .: Heterotrimeric G
proteins
46. G protein-coupled receptors span the membrane with how many alpha-he- lical domains?: Seven
47. The binding site of each ligand of the superfamily of membrane proteins is either on the extracellular portion of the protein ( ) or in the mem- brane-spanning portion ( ), whereas the cytoplasmic portion binds to the
.: Large ligands, small ligands, G protein
48. Makes up the third largest family of genes in humans: Superfamily of mem- brane proteins
49. Nearly half of all nonantibiotic prescription drugs are targeted toward...: G
protein-coupled receptors
50. A protein can also be attached to the membrane via . The protein is covalently attached to a lipid molecule, which is then embedded in one leaflet of the bilayer.: Lipid anchors
51. anchors protein to the outer leaflet of the membrane.: Glycosylphos- phatidylinositol (GPI)
52. Proteins can be attached to the inner leaflet via their or via their
.: Amino terminus by fatty acids (e.g., myristate or palmitate), carboxyl-terminus by prenyl anchors (e.g., farnesyl or geranylgeranyl)
53. May be associated with the polar head groups of the membrane lipids, bu they more commonly bind to integral or lipid anchored proteins: Peripheral proteins
54. In many cells, some of the outer leaflet lipids, as well as many of the proteins exposed on the outer surface of the membrane are .: Glycosylated
55. Have short chains of sugars, oligosaccharides, attached to them: Glycosy- lated
56. Collectively, glycolipids and glycoproteins form what is called the .: -
Glycocalyx
57. The membrane transport proteins or transporters: Plasma membrane pro- teins
58. Approximately 10% of human genes (~2000) code for...: Transporters
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