1
Q
- Which of the following is not part of a cell membrane?
a. Cholesterol
b. Phospholipid
c. Ubiquitin
d. Integral proteins
e. Glycolipids
A
c
2
Q
- A molecule that consists of a polar portion and a nonpolar portion is said to be
a. hydrophilic.
b. an emergent property.
c. hydrophobic.
d. an integral protein.
e. amphipathic.
A
e
3
Q
- A saturated hydrocarbon tends to
a. contain no double bonds.
b. be more solid at colder temperatures compared to an unsaturated hydrocarbon.
c. contain many double bonds.
d. Both a and b
e. Both b and c
A
d
4
Q
- Compared to fish found in lower temperature habitats, fish that inhabit higher temperatures tend to have
a. more saturated phospholipids in their brain synaptic membranes.
b. more saturated phospholipids in their brain proteins.
c. more unsaturated phospholipids in their brain synaptic membranes.
d. more unsaturated phospholipids in their brain proteins.
e. equal amounts of saturated and unsaturated brain proteins.
A
a
5
Q
- Which of the following membrane proteins is responsible for the passive movement of K+ across the typical animal cell membrane?
a. Channel
b. Enzyme
c. Transporter
d. Receptor
e. Structural protein
A
a
6
Q
- When a protein is denatured, which of the following structures is disrupted first?
a. Primary
b. Secondary
c. Tertiary
d. Quarternary
e. Amino acid
A
c
7
Q
- Which of the following is not a type of functional membrane protein?
a. An aqueous pore
b. Cholesterol
c. The Na+‒K+ pump
d. A receptor protein
e. Cytoskeletal filaments
A
b
8
Q
- A ring of _______ demarcates the apical surface of the cell from its lateral and basal surfaces.
a. tight junctions
b. septate junctions
c. gap junctions
d. epithelia
e. microvilli
A
a
9
Q
- Which of the following is not an occluding junction?
a. Gap junction
b. Tight junction
c. Septate junction
d. Both a and b
e. Both b and c
A
a
10
Q
- _______ is (are) the specific set of processes by which complex chemical compounds are broken down to release energy, create smaller chemical building blocks, or prepare chemical constituents for elimination.
a. Metabolism
b. Catabolism
c. Anabolism
d. Nitrogen metabolism
e. Biochemical reactions
A
b
11
Q
- Per gram, the leopard frog can jump farther per jump compared to the western toad because the leopard frog
a. is insensitive to lactic acid.
b. tends to live in warmer climates.
c. has a higher aerobic capacity.
d. creates more lactic acid per unit time.
e. is much larger.
A
d
12
Q
- Which of the following statements regarding enzymes is false?
a. All enzymes are catalysts.
b. Enzymes have substrates and products.
c. Enzymes speed chemical reactions.
d. All catalysts are enzymes.
e. Enzymes often regulate reactions.
A
d
13
Q
- Which of the following reactions is catalyzed by LDH?
a. Pyruvic acid + NADH2 → lactic acid + NAD
b. Lactic acid + NAD → pyruvic acid + NADH2
c. Pyruvic acid + NAD → lactic acid + NADH2
d. Lactic acid + NADH2 → pyruvic acid + NAD
e. Both a and b
A
e
14
Q
- The amount of substrate converted to product per unit of time is called the
a. turnover number.
b. saturated speed.
c. Vmax.
d. enzyme affinity.
e. reaction velocity.
A
e
15
Q
- Turnover number (kcat) describes what property of an enzymatic reaction?
a. Activation energy
b. Half the maximum reaction velocity
c. Catalytic effectiveness
d. Enzyme‒substrate affinity
e. The transition state
A
c
16
Q
- The likelihood that an enzyme will form a complex with the substrate during a collision is called the
a. catalytic effectiveness.
b. maximum reaction velocity.
c. activation energy.
d. enzyme‒substrate affinity.
e. transition state.
A
d
17
Q
- An enzymatic reaction is proceeding at subsaturation. Which of the following is not a means by which the enzymatic reaction can be increased?
a. Adding more substrate
b. Adding more enzyme
c. Increasing the catalytic effectiveness
d. Increasing the enzyme‒substrate affinity
e. Increasing the temperature
A
b
18
Q
- An interaction in which the binding of nonsubstrate ligands to the enzyme decreases its affinity for the substrate is called
a. allosteric inhibition.
b. negative cooperativity.
c. heterotropic cooperativity.
d. allosteric activation.
e. competitive inhibition.
A
a
19
Q
- Human LDH-B4 and rat LDH-B4 are examples of
a. isozymes.
b. analogous enzymes.
c. isoenzymes.
d. intraspecific enzyme homologs.
e. interspecific enzyme homologs.
A
e
20
Q
- An enzyme-encoding gene is considered to be_______ within a cell if the gene results in the synthesis of the encoded enzyme within that same cell.
a. promoted
b. expressed
c. induced
d. enhanced
e. constituted
A
b
21
Q
- _______ enzymes are present in a tissue in relatively high and steady amounts regardless of conditions, whereas _______ enzymes are present at low levels (or not at all) in a tissue unless their synthesis is activated.
a. Inducible; constitutive
b. Promotable; inducible
c. Constitutive; expressed
d. Constitutive; inducible
e. Expressed; promotable
A
d
22
Q
- Which of the following statements regarding allosteric modulation is false?
a. The binding of an allosteric modulator follows the law of mass action.
b. The binding of an allosteric modulator is reversible.
c. An allosteric modulator, when present, will always bind to the enzyme it modulates.
d. The binding of an allosteric modulator can increase the catalytic activity of the enzyme.
e. The binding of an allosteric modulator can decrease the catalytic activity of the enzyme.
A
c
23
Q
- Citrate combines with phosphofructokinase at the _______ site, ultimately _______ catalytic activity and thus regulating glycolysis.
a. allosteric; increasing
b. allosteric; decreasing
c. active; increasing
d. active; decreasing
e. covalent; increasing
A
b
24
Q
- Which of the following is not involved in covalent modulation?
a. Phosphorylation
b. Protein kinases
c. van der Waals interactions
d. Enzymes
e. Protein phosphatases
A
c
25
32. A protein kinase catalyzes the phosphorylation of another protein kinase, which in turn catalyzes the phosphorylation of a third protein kinase. This series of multiple enzyme sequences is an excellent example of
a. amplification.
b. a rate-limiting reaction.
c. a series expression.
d. inducing enzymes.
e. allosteric regulation.
a
26
33. The _______ is/are directly responsible for the amplifying effects during a second messenger cascade.
a. receptors
b. substrates
c. enzymes
d. cell membrane
e. orthophosphate groups
c
27
38. In rats, phosphoenolpyruvate carboxykinase activity per gram of liver significantly increases at birth and remains at the higher level for the life of the animal. This is an example of enzymatic change that takes place over a(n) _______ time frame.
a. acute
b. chronic
c. evolutionary
d. developmental
d
28
39. If a protein in situ becomes partially denatured because of high temperature, the denaturation can be reversed by a
a. molecular chaperone.
b. heat-shock protein.
c. stress protein.
d. Both a and b
e. All of the above
e
29
40. Which of the following tags proteins for destruction?
a. Proteasome
b. Ubiquitin
c. Photocyte
d. Molecular chaperone
e. Heat-shock protein
b
30
41. The process of absorbing preexisting light and re-emitting it at longer wavelengths is called
a. bioluminescence.
b. pigment aggregation.
c. reflection.
d. chromatophoration.
e. fluorescence.
e
31
42. The ability of animals to change color in seconds or minutes depends on the function of
a. photocytes.
b. chromatophores.
c. photoproteins.
d. luciferin.
e. luciferase.
b
32
43. Intracellular modification of activity in response to an external signal is an example of
a. transduction.
b. transformation.
c. conversion.
d. the electrochemical gradient.
e. covalent modulation.
a
33
44. Extracellular signaling molecules initiate their actions on a cell by binding with certain protein molecules of the cell called
a. ligands.
b. peripheral proteins.
c. integral proteins.
d. receptors.
e. structural proteins.
d
34
45. Which of the following statements regarding the ligand-gated receptor is false?
a. The naturally occurring ligand can cause the associated protein channel to open.
b. The naturally occurring ligand should bind irreversibly to the receptor until it breaks down.
c. A similarly shaped foreign ligand can attach to the receptor and block the naturally occurring ligand from binding.
d. The receptor surface is usually extracellular.
e. A ligand can attach to the receptor and activate an intracellular catalytic site on the same molecule.
b
35
46. Receptor proteins can bring about all of the following cellular actions except
a. reinforcing the structure of the membrane.
b. opening a protein channel on the membrane.
c. activating an enzyme on the intracellular surface.
d. combining with a ligand to initiate transcription.
e. activating a G protein.
a
36
47. The α-conotoxin injected into fish by the cone snail binds to and therefore blocks receptor sites on the muscle membrane. This prevents
a. an enzyme from being activated.
b. a G protein from being activated.
c. transcription from occurring.
d. a channel from opening into the nucleus.
e. a channel from opening.
e
37
48. Which of the following reactions does not produce an amplification?
a. Activation of a G protein by an activated receptor
b. Formation of cyclic AMP by catalyzing action of adenylyl cyclase
c. Activation of glycogen phosphorylase kinase by active cAMP-dependent protein kinase
d. Conversion of glycogen to glucose by active glycogen phosphorylase
e. All of the above are amplifying reactions.
e
38
49. Which of the following is not considered a second messenger?
a. Cyclic GMP
b. Cyclic AMP
c. Calcium ions
d. Epinephrine
e. 1,2-diacylglycerol (DAG)
D
39
50. As a second messenger, calcium typically binds to
a. calmodulin, and the complex activates protein kinases.
b. a G protein to activate general second messengers.
c. cyclic AMP to activate cAMP-dependent protein kinases.
d. nitric oxide to activate cytoplasmic guanylyl cyclase.
e. inositol triphosphate to activate the endoplasmic reticulum.
A
40
1. Which of the following statements regarding brain phospholipids in fish is most accurate?
a. Tropical fish tend to have very unsaturated phospholipids in their brain synaptic membranes.
b. Fish in very cold habitats tend to have very saturated phospholipids in their brain synaptic membranes.
c. The colder the habitat, the greater the degree of phospholipid unsaturation in the brain synaptic membranes.
d. The degree of phospholipid saturation in brain synaptic membranes is independent of habitat temperature.
e. All of the above statements are equally accurate.
C
41
2. Which of the following is not a functional type of membrane protein?
a. Transporter
b. Enzyme
c. Receptor
d. Structural
e. Resistance
E
42
. Which of the following cell‒cell junctions allows cytoplasmic flow between the connected cells?
a. Tight junction
b. Septate junction
c. Gap junction
d. Desmosome
e. Occluding junction
C
43
4. When there are more substrate molecules than the enzyme molecules can accommodate, the reaction is
a. saturated.
b. subsaturated.
c. showing sigmoid reaction kinetics.
d. showing the highest enzyme–substrate affinity.
e. at its Km.
A
44
5. The catalytic effectiveness of an enzyme molecule is expressed as the
a. half-saturation constant, Km.
b. enzyme–substrate affinity.
c. activation energy during a saturated reaction.
d. number of substrate molecules converted to product per second by each enzyme molecule when saturated.
e. maximum velocity, Vmax.
D
45
6. The allosteric site is located
a. on the enzyme.
b. on the substrate.
c. on the cell surface.
d. on the modulator.
e. in the cytoplasm.
A
46
7. Human LDH-A4 and rat LDH-A4 together are a good example of
a. isozymes.
b. interspecific enzyme homologs.
c. allosteric modulators.
d. positive cooperativity.
e. ligands.
B
47
8. An animal is exposed to halogenated aromatic hydrocarbons, and as a result, its levels of P450 enzymes rise. This is an excellent example of the action of
a. a promotor.
b. transcription factors.
c. enhancers.
d. constitutive enzymes.
e. inducible enzymes.
E
48
9. When an allosterically modulated enzyme is the rate-limiting enzyme in a metabolic pathway, the entire pathway may be upregulated or downregulated by allosteric modulation. The result of downregulation of the entire pathway is called
a. a branch-point reaction.
b. feedback inhibition.
c. positive feedback.
d. covalent modulation.
e. phosphorylation.
B
49
10. Multiple-enzyme sequences in which each enzyme in the sequence activates another enzyme is an example of
a. the action of protein kinases.
b. covalent modulation.
c. allosteric modulation.
d. amplification.
e. feedback inhibition.
D
50
11. The example of killifish allele frequency distribution along the Atlantic coast describes enzyme changes over a(n) _______ time frame.
a. acute
b. chronic
c. evolutionary
d. developmental
e. reproductive
C
51
12. Molecular chaperones can be expressed during
a. heat stress.
b. cold stress.
c. hypoxic stress
d. Both a and b
e. All of the above
E
52
13. In a bioluminescent animal such as the hydromedusa jellyfish Aequorea victoria, the photoprotein consists of
a. luciferin.
b. O2.
c. a protein.
d. Both b and c
e. All of the above
E
53
14. Color change in fish depends on flattened pigment-containing cells called
a. pigment granules.
b. photoproteins.
c. chromatophores.
d. photocytes.
e. chromocytes.
C
54
15. Which of the following receptor proteins bring(s) about cascades of membrane proteins involving significant amplification?
a. Ligand-gated channel and G protein–coupled receptor
b. G protein–coupled receptor
c. Enzyme/enzyme-linked receptor and intracellular receptors
d. G protein–coupled receptor and enzyme/enzyme-linked receptor
e. Enzyme/enzyme-linked receptor
B
55
16. Which of the following receptor proteins change(s) membrane voltage immediately when activated?
a. Ligand-gated channel
b. G protein–coupled receptor
c. Enzyme/enzyme-linked receptor
d. Intracellular receptors
e. G protein–coupled receptor and enzyme/enzyme-linked receptor
A
56
17. Which of the following receptor proteins activate(s) enzymes on the cell membrane?
a. Ligand-gated channel and G protein–coupled receptor
b. G protein–coupled receptor and enzyme/enzyme-linked receptor
c. Enzyme/enzyme-linked receptor and intracellular receptors
d. Ligand-gated channel, G protein–coupled receptor, and enzyme/enzyme-linked receptor
e. Ligand-gated channel and intracellular receptors
B
57
18. Which of the following receptor proteins interact(s) with DNA?
a. Ligand-gated channel
b. G protein–coupled receptor
c. Enzyme/enzyme-linked receptor
d. Intracellular receptors
e. G protein–coupled receptor and enzyme/enzyme-linked receptor
D
58
19. When epinephrine attaches to a(n) _______, the process of _______ results in the formation of a large amount of intracellular _______.
a. G protein‒coupled receptor; amplification; glucose
b. ligand-gated receptor; amplification; glucose
c. G protein‒coupled receptor; metabolic pathways; glycogen
d. enzyme-enzyme‒linked receptor; amplification; glycogen
e. intracellular receptor; protein expression; glucose
A
59
20. Which of the following is not involved at the cell membrane in a second messenger cascade?
a. Adenylyl cyclase
b. Guanylyl cyclase
c. G protein‒coupled receptor
d. Protein kinase
e. Phospholipase C
D
animal physiology
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