FL Exam #2

Question 1

The general experimental procedure was as follows: (1) purified rabbit proteasome (2 nM) was incubated in the presence of porphyrin at 37°C for 30 minutes; (2) the reaction was initiated by addition of the peptide (100 μM); and (3) intensity of fluorescence emission at 440 nm (excitation at 360 nm) was monitored for 20 minutes.

What expression gives the amount of light energy (in J per photon) that is converted to other forms between the fluorescence excitation and emission events?

A. (6.62 × 10^–34) × (3.0 × 10⁸)

B. (6.62 × 10^–34) × (3.0 × 10⁸) × (360 × 10^–9)

C. (6.62 × 10^–34) × (3.0 × 10⁸) × [1 / (360 × 10^–9) – 1 / (440 × 10^–9)]

D. (6.62 × 10^–34) × (3.0 × 10⁸) / (440 × 10^–9)

Answer 1

The answer to this question is C.

The equation of interest is E = hf = hc/λ, where h = 6.62 × 10 ⁻³⁴ J ∙ s and c = 3 × 10 ⁸ m/s.

Excitation occurs at λ_e = 360 nm, but fluorescence is observed at λ_f = 440 nm. This implies that an energy of E = (6.62 × 10 ⁻³⁴) × (3 × 10 ⁸) × [1 / (360 × 10 ⁻⁹) − 1 / (440 × 10 ⁻⁹)] J per photon is converted to other forms between the excitation and fluorescence events.

Question 2

Which amino acid is found in greatest abundance in the active site of a laccase?

A. Phe

B. Tyr

C. His

D. Cys

Answer 2

The answer to this question is C.

The five-membered imidazole rings depicted in Figure 1 are associated with histidine, an amino acid whose side chain is frequently encountered at the active site of metalloenzymes.

Question 3

A person is sitting on a chair as shown.

Why must the person either lean forward or slide their feet under the chair in order to stand up?

A. To increase the force required to stand up

B. To use the friction with the ground

C. To reduce the energy required to stand up

D. To keep the body in equilibrium while rising

Answer 3

The answer to this question is D.

As the person is attempting to stand, the only support comes from the feet on the ground. The person is in equilibrium only when the center of mass is directly above their feet.

Otherwise, if the person did not lean forward or slide the feet under the chair, the person would fall backward due to the large torque created by the combination of the weight of the body (applied at the person’s center of mass) and the distance along the horizontal between the center of mass and the support point.

Question 4

Asymmetry resulting from tertiary structural features causes the largest increase in CD signal intensity in the near UV region (250–290 nm) of peptides. The side chains of aromatic amino acid residues absorb in this region. The asymmetry of the α-carbon atom does not impact the CD signal of the aromatic side chain nor do elements of secondary structure.

The side chain of tryptophan will give rise to the largest CD signal in the near UV region when:

A. present as a free amino acid.

B. part of an α-helix.

C. part of a β-sheet.

D. part of a fully folded protein.

Answer 4

The answer to this question is D.

Tryptophan has an aromatic side chain that will give rise to a significant CD signal in the near UV region if it is found in a fully folded protein.

Question 5

The peptide bond absorbs in the far UV region (190–250 nm). The CD signals of these bonds are dramatically impacted by their proximity to secondary structural elements.

Asymmetry resulting from tertiary structural features causes the largest increase in CD signal intensity in the near UV region (250–290 nm) of peptides. The side chains of aromatic amino acid residues absorb in this region. The asymmetry of the α-carbon atom does not impact the CD signal of the aromatic side chain nor do elements of secondary structure.

Which amino acid will contribute to the CD signal in the far UV region, but NOT the near UV region when part of a fully folded protein?

A. Trp

B. Phe

C. Ala

D. Tyr

Answer 5

The answer to this question is C.

All chiral nonaromatic amino acids will contribute solely to the CD signal in the far UV region.

Question 6

Based on the relative energy of the absorbed electromagnetic radiation, which absorber, a peptide bond or an aromatic side chain, exhibits an electronic excited state that is closer in energy to the ground state?

Asymmetry resulting from tertiary structural features causes the largest increase in CD signal intensity in the near UV region (250–290 nm) of peptides. The side chains of aromatic amino acid residues absorb in this region. The peptide bond absorbs in the far UV region (190–250 nm).

A. An aromatic side chain; the absorbed photon energy is higher.

B. An aromatic side chain; the absorbed photon energy is lower.

C. A peptide bond; the absorbed photon energy is higher.

D. A peptide bond; the absorbed photon energy is lower.

Answer 6

The answer to this question is B.

Aromatic side chains absorb in the near UV region of the electromagnetic spectrum, which has longer wavelengths, and hence lower energy, than peptide bonds.

Because the energy of the photon matches the energy gap between the ground and the excited state, this implies that the aromatic side chain has more closely spaced energy levels.

Question 7

A synthetic peptide with the amino acid sequence KTFCGPEYLA was generated as a mimic of the T-loop.

What is the net charge of sT-loop at pH 7.2?

A. –2

B. –1

C. 0

D. +1

Answer 7

The answer to this question is C.

At pH 7.2, the N-terminus will be positively charged and the C-terminus will be negatively charged.

In addition, the lysine side chain will carry one positive charge and the glutamic acid side chain will carry one negative charge.

Question 8

This synthetic T-loop (sT-loop) was incubated with ³²P-labeled ATP in the presence of PDK1 for different time periods at 37 ° C and pH 7.2, and the amount of radioactivity incorporated into sT-loop was measured by detection of β– decay.

In designing the experiment, the researchers used which type of ³²P labeled ATP?

A. α³²P-ATP

B. β³²P-ATP

C. γ³²P-ATP

D. δ³²P-ATP

Answer 8

The answer to this question is C.

The phosphoryl transfer from kinases comes from the γ-phosphate of ATP.

Therefore, the experiment should require γ³²P-ATP.

Question 9

This experiment was repeated in the presence of a synthetic peptide that mimics the HM domain (sHM) of Ser/Thr kinases with the amino acid sequence FLGFTY. Phosphorylated sHM (spHM) was also used in place of sHM.

When used in place of spHM, which peptide would be most likely to achieve the same experimental results?

A. FLGFAY

B. FLGFQY

C. FLGFGY

D. FLGFEY

Answer 9

The answer to this question is D.

The phosphorylated threonine would most likely be mimicked by glutamic acid.

Question 10

The curve of a cooperative process has which shape?

Answer 10

sigmoidal

Question 11

Which of the following best describes the bonds between Cu²⁺ and the nitrogen atoms of the ammonia molecules in [Cu(NH₃)₄]²⁺?

A. Ionic

B. Covalent

C. Coordinate ionic

D. Coordinate covalent

Answer 11

The answer to this question is D.

The Lewis acid–base interaction between a metal cation and an electron pair donor is known as a coordinate covalent bond.

Question 12

In [Cu(NH₃)₄]²⁺, the subscript 4 indicates which of the following?

A. The oxidation number of Cu only

B. The coordination number of Cu²⁺ only

C. Both the oxidation number of Cu and the coordination number of Cu²⁺

D. Neither the oxidation number of Cu nor the coordination number of Cu²⁺

Answer 12

The answer to this question is B.

Because ammonia is neutral, the number 4 reflects only the number of ammonia molecules that bind to the central Cu²⁺ cation and does not indicate anything about its oxidation number.

Question 13

4C₃H₅N₃O₉(l) → 12CO₂(g) + 10H₂O(g) + 6N₂(g) + O₂(g)

Reaction 1

At STP, the volume of N₂(g) produced by the complete decomposition of 1 mole of nitroglycerin would be closest to which of the following?

A. 5 L

B. 10 L

C. 20 L

D. 30 L

Answer 13

The answer to this question is D.

Based on the balanced equation provided, 4 moles of nitroglycerin produces 6 moles of N2(g).

Therefore, 1 mole of nitroglycerin will produce 1.5 moles of N2(g). At STP 1.5 moles of N2(g) will occupy 33.6 L since the molar volume of an ideal gas at STP is 22.4 L/mol.

Question 14

Which of the following energy conversions best describes what takes place in a battery-powered resistive circuit when the current is flowing?

A. Electric to thermal to chemical

B. Chemical to thermal to electric

C. Electric to chemical to thermal

D. Chemical to electric to thermal

Answer 14

The answer to this question is D.

The chemical energy of the battery elements is used as electrical energy to set the charge carriers in motion through the resistor, where they experience drag from the crystal lattice of the resistive conductor and dissipate their energy as heat from the resistor.

Question 15

Protein secondary structure is characterized by the pattern of hydrogen bonds between:

A. backbone amide protons and carbonyl oxygens.

B. backbone amide protons and side chain carbonyl oxygens.

C. side chain hydroxyl groups and backbone carbonyl oxygens.

D. side chain amide protons and backbone carbonyl oxygens.

Answer 15

The answer to this question is A.

Secondary structure is represented by repeated patterns of hydrogen bonds between the backbone amide protons and carbonyl oxygen atoms.

Question 16

What is the major pathway for ATP production once the electron transport chain is shut down?

Answer 16

glycolysis

Question 17

Why was it necessary for the researchers to determine the activity of the complex I, II, and III of the ETC independent of one another?

A. Complex stability is lost if the complexes are able to interact structurally.

B. The complexes have different cellular locations, and it is not feasible to isolate them together.

C. The complexes all use the same substrates, so their use must be monitored separately.

D. The reactions catalyzed by the complexes are coupled to one another.

Answer 17

The answer to this question is D.

Studying the complexes all together would lead to erroneous results because inhibition of complexes I and II affects the activity of Complex III, which affects the activity of Complex IV.

Question 18

In the absence of Frizzled activation, CK1 and GSK3 sequentially phosphorylate β-catenin, which targets it for ubiquitination.

In the absence of Frizzled activation, β-catenin is covalently modified and:

A. bound by a proteasome to initiate degradation into short peptides.

B. translocated into the Golgi body for secretion through exocytosis.

C. engulfed by a lysosome where it is hydrolyzed by proteases.

D. stored in vesicles until the signaling pathway is activated.

Answer 18

The answer to this question is A.

According to the passage, in the absence of Frizzled activation, β-catenin is phosphorylated and ubiquitinated. Ubiquitination targets a protein for degradation by a proteasome.

Question 19

What is the best experimental method to analyze the effect of tdh2 gene deletion on the rate of histone acetylation? Comparing histone acetylation in wild-type and Δtdh2 cells by:

A. Western blot

B. Southern blot

C. Northern blot

D. RT-PCR

Answer 19

The answer to this question is A.

Posttranslational modification of proteins such as histone acetylation is analyzed by Western blotting.

Question 20

Which experimental approach(es) can be used to analyze the effect of ROS on the lifespan of yeast? Comparing the lifespans of:

I. wild-type yeast versus yeast lacking antioxidant enzymes

II. wild-type yeast versus yeast overexpressing antioxidant enzymes

III. yeasts growing in the presence or absence of hydrogen peroxide

A. I only

B. II only

C. II and III only

D. I, II, and III

Answer 20

The answer to this question is D.

All listed options influence ROS levels in yeast and can be used to analyze the role of ROS in regulating the lifespan of yeast.

Question 21

Vasopressin regulates the insertion of aquaporins into the apical membranes of the epithelial cells of which renal structure?

A. Collecting duct

B. Proximal tubule

C. Bowman’s capsule

D. Ascending loop of Henle

Answer 21

The answer to this question is A.

Vasopressin regulates the fusion of aquaporins with the apical membranes of the collecting duct epithelial cells.

Question 22

G542X is another CFTR allele. If a female heterozygous for G542X bears a child fathered by a male heterozygous for the ΔF508 allele, what is the probability that the child would be homozygous for the G542X allele, given that neither parent has CF?

A. 0.00

B. 0.25

C. 0.75

D. 1.00

Answer 22

The answer to this question is A.

Both parents would need to carry the G542X allele in order for a child to be homozygous for the G542X allele.

Because only the mother carries the G542X allele, the probability that the child will be homozygous for the G542X allele is 0.

Question 23

The infectivity of VSV-EGP, vesicular stomatitis virus (VSV) particles engineered to contain EGP instead of VSV glycoprotein in the viral envelope, was reduced more than 99-fold by inhibitors of the mammalian proteases CatB and CatL.

Based on the passage, CatB or CatL or both would be expected to have which of the following effects, if any, on EGP?

A. No effect

B. Reduction of enzyme activity

C. Formation of protein dimers

D. Digestion into smaller protein fragments

Answer 23

The answer to this question is D.

The passage states that CatB and CatL are proteases. Proteases function to digest proteins into smaller fragments.

Question 24

The precursor of EGP is translated from a transcript that has had one nontemplated nucleotide added to the open reading frame. This change does not create or eliminate a stop codon. Compared with the protein sGP, which is produced from the unedited transcript, EGP most likely has the same primary:

A. amino-terminal sequence as sGP, but a different primary carboxy-terminal sequence.

B. carboxy-terminal sequence as sGP, but a different primary amino-terminal sequence.

C. sequence as sGP except that EGP has one additional amino acid.

D. sequence as sGP except that EGP has one less amino acid.

Answer 24

The answer to this question is A.

The addition of one nucleotide to the open reading frame of EGP results in a frameshift mutation and an aberrant carboxy-terminal domain.

Question 25

Melanosomes most likely move along microtubules that originate in and radiate from the: A. centrosome. B. kinetochores. C. Golgi apparatus. D. microfilaments under the plasma membrane.

Answer 25

The answer to this question is **A** Microtubules are cellular structures that originate from centrosomes.

Question 26

Where in the human male reproductive system do the gametes become motile and capable of fertilization? A. Testis B. Urethra C. Epididymis D. Prostate gland

Answer 26

The answer to this question is **C** Sperm, produced in the seminiferous tubules of the testes, completes maturation and becomes motile in the epididymis.

Question 27

According to the cross-bridge model of muscle contraction, the muscles stiffen after death because ATP is unavailable to bind and directly release: A. ADP from the actin head. B. ADP from the myosin head. C. the actin head from the myosin filament. D. the myosin head from the actin filament.

Answer 27

The answer to this question is **D** During normal muscle contraction, ATP is required to break the bonds between the actin filament and the myosin head. After death, no new ATP is generated so the myosin head cannot be released from the actin filament, resulting in stiffening of muscles.

Question 28

Which information from the passage contradicts the socioeconomic gradient in health? A. The U.S. has a comparatively high median household income. B. The U.S. health disadvantage exists for all social classes. C. The U.S. lags behind peer countries in health indicators. D. The U.S. health disadvantage is explained by social capital.

Answer 28

The answer to this question is **B.** The socioeconomic gradient in health refers to the graded relationship between social class and health, in which each “step” up on the hierarchy of social stratification tends to be associated with better health. In stating that the U.S. health disadvantage exists across social classes, this assertion from the passage challenges the protective aspect of advantaged social class that is implied by the socioeconomic gradient in health.

Question 29

Which hypothetical result from the online questionnaire would provide evidence of the fundamental attribution error? A. Some participants rank personality factors above environmental factors. B. Some participants rank genetic factors above personality factors. C. Some participants rank environmental factors over both personality and genetic factors. D. Some participants rank genetic factors over both personality and environmental factors.

Answer 29

The answer to this question is **A.** The fundamental attribution error refers to stressing the importance of dispositional (i.e., personality) factors in one’s explanations of other people’s behavior and underemphasizing situational factors.

Question 30

A study finds that individuals who follow a weekly exercise routine exhibit less immunity decline compared to those who do not. The exercise group only included participants who exercised regularly, whereas the comparison group only included those who did not exercise regularly. Which statement does NOT identify a limitation of this research design? A. The study lacks random assignment. B. The study has a possible sampling bias. C. The study lacks replicable results. D. The study has a possible confound.

Answer 30

The answer to this question is **C.** The study lacks random assignment because the two groups were composed of individuals with established exercise habits. Because the participants were not equally likely to be in the two groups, there is a potential bias in the sample. In addition, exercise habits pose a potential confound because the group that already exercises regularly could differ from the comparison group in a number of ways. However, there is nothing about the hypothetical study that excludes the possibility of replicable results. Keeping in mind that the question asks for what is NOT a limitation, the incorrect options identify important methodological limitations of the study whereas the correct answer does not.

Question 31

During the discussions, participants in the social identity condition groups were more likely to exhibit groupthink symptoms such as making more rationalizations, introducing fewer facts, and discussing risks less frequently. Based on the findings in Study 2, which strategy for decision-making groups would be most likely to prevent groupthink? A. Make certain that all decision-making groups are made up of groups of friends. B. Whenever possible, avoid the selection of a group leader through popular vote. C. Encourage a group norm of critical evaluation and dissent in decision-making. D. Require decision-making groups to verify that groupthink did not influence their decision.

Answer 31

The answer to this question is **C.** Those in the social identity condition exhibited more groupthink symptoms than those in the interpersonal condition. They make more rationalizations, introduce fewer facts, and discuss risks less frequently. Pressures to reach consensus and stifle dissent are key to groupthink, and thus a group norm that encouraged dissent and critical evaluation would address the central problem of groupthink.

Question 32

A researcher is interested in how anxiety disorders affect escape learning. Which procedure is most appropriate for assessing the dependent variable in this study? A. Having the participants fill out a validated questionnaire that screens for anxiety disorders B. Having a trained practitioner assess the participants for anxiety disorders C. Monitoring how many trials it takes for participants to avoid a response that results in an electric shock when the electric shock is signaled with a tone D. Monitoring how many trials it takes for participants to be conditioned to perform a response that results in the termination of an electric shock

Answer 32

The answer to this question is D. The purpose of the study was to determine how anxiety disorders affect escape learning, and this option is the only one that refers to the empirical observation of escape behavior.

Question 33

A fear conditioning paradigm was used whereby in the first phase, foot shock, which induces fear in mice, was paired with a bright light for many trials. The first phase of the fear conditioning paradigm, as described in the study, is known as: A. discrimination. B. acquisition. C. shaping. D. generalization.

Answer 33

The answer to this question is **B.** In the acquisition phase of the fear conditioning paradigm, a stimulus (light) that is neutral with respect to the freezing response is associated with an unconditioned stimulus (in this case, foot shock) over a series of trials, until the neutral stimulus elicits a conditioned response (freezing behavior in response to the light).

Question 34

How would a structural functionalist interpret the efficacy of yoga as part of smoking cessation therapy? A. Yoga provides an alternate understanding of healthful practices that enables the individual to better understand his or her personal needs and motives. B. Yoga provides an inexpensive therapy option for those lacking the financial resources necessary for more expensive medical interventions. C. The utility of yoga as an effective smoking cessation therapy stems from the transformation of the individual’s self-concept as a nonsmoker. D. The utility of yoga as an effective smoking cessation therapy is an unintended, though beneficial, the outcome of a yoga practice.

Answer 34

The answer to this question is **D.** Because the expected function of yoga is not specifically smoking cessation, its utility as a cessation therapy is a latent function of the social activity. The sociological paradigm of functionalism makes a distinction between manifest or intended, and latent or unintended functions of social activities. From the functionalist perspective, almost all social actions have both manifest functions and latent functions, both of which are connected to overall social stability. The other response options with the question are better linked to the conflict or symbolic interactionist perspectives in sociology.