Week Four Quiz

The quiz is divided into two sections. The first section contains questions that assess your recall of essential biological facts. The second set of questions asks you to apply your knowledge of material presented to solve clinical or research problems. The questions in the second set are similar to what you will encounter on the self-assessment and qualifier.

Instructions: To check your answer, click on the option you think is correct.

  1. Which of the following is the primary function of the urea cycle?

    1. Synthesis of glucose
    2. Conversion of ammonia to urea
    3. Production of ATP
    4. Metabolism of fatty acids
  2. In which organ does the urea cycle predominantly occur?

    1. Kidney
    2. Liver
    3. Heart
    4. Muscle
  3. Which enzyme is responsible for the formation of carbamoyl phosphate in the urea cycle?

    1. Ornithine transcarbamylase
    2. Carbamoyl phosphate synthetase I
    3. Arginase
    4. Arginosuccinate synthetase
  4. Which compound enters the urea cycle to combine with carbamoyl phosphate?

    1. Citrulline
    2. Ornithine
    3. Arginine
    4. Aspartate
  5. Allopurinol, a medication used to manage gout, works by inhibiting which enzyme?

    1. Xanthine oxidase
    2. Ribonucleotide reductase
    3. Adenosine deaminase
    4. Glutamine-PRPP amidotransferase
  6. Which metabolic pathway is most directly involved in the formation of uric acid?

    1. Purine breakdown
    2. Pyrimidine metabolism
    3. Nucleotide salvage pathway
    4. De novo pyrimidine synthesis
  7. What is the role of ribose-5-phosphate in purine metabolism?

    1. It inhibits xanthine oxidase.
    2. It is the substrate in the first step of purine synthesis.
    3. It is a product of purine catabolism.
    4. It is used in the synthesis of pyrimidines.
  8. In purine metabolism, which of the following substances is converted to uric acid by xanthine oxidase?

    1. Hypoxanthine
    2. Adenosine.
    3. Thymidine
    4. UMP
  9. Which vitamin is essential for the synthesis of purine nucleotides?

    1. Vitamin B12
    2. Vitamin C
    3. Folic acid
    4. Vitamin D
  10. Where does the majority of fatty acid β-oxidation occur in the cell?

    1. Nucleus
    2. Cytosol
    3. Mitochondria
    4. Endoplasmic Reticulum
  11. Which enzyme is responsible for the activation of fatty acids before β-oxidation?

    1. Carnitine acyltransferase I
    2. Acyl-CoA synthetase
    3. Acetyl-CoA carboxylase
    4. HMG-CoA reductase Reticulum
  12. What is the primary product of each round of β-oxidation?

    1. NADH
    2. FADH2
    3. Acetyl-CoA
    4. ATP
  13. In the well-fed state, which of the following hormones stimulates fatty acid synthesis?

    1. Glucagon
    2. Epinephrine
    3. Insulin
    4. Cortisol
  14. What is the major site of ketone body utilization?

    1. Liver
    2. Brain
    3. Adipose tissue
    4. Kidney
  15. Which cofactor is essential for fatty acid synthesis?

    1. NADH
    2. FAD
    3. NADPH
    4. Coenzyme Q
  16. The process of gluconeogenesis primarily occurs in which organ?

    1. Kidney
    2. Liver
    3. Muscle
    4. Adipose tissue
  17. In the fed state, which organ is primarily responsible for regulating blood glucose levels?

    1. Muscle
    2. Adipose tissue
    3. Liver
    4. Brain
  18. What is the main regulatory enzyme in glycolysis?

    1. Hexokinase
    2. Pyruvate kinase
    3. Phosphofructokinase-1 (PFK-1)
    4. Glucose-6-phosphate dehydrogenase
  19. Which enzyme is primarily responsible for unwinding the DNA double helix during replication?

    1. DNA polymerase
    2. Topoisomerase
    3. Helicase
    4. Primase
  20. What is the function of DNA primase during DNA replication?

    1. Unwinding the DNA
    2. Synthesizing the leading strand
    3. Laying down RNA primers
    4. Repairing damaged DNA
  21. What is the function of DNA primase during DNA replication?

    1. Unwinding the DNA
    2. Synthesizing the leading strand
    3. Laying down RNA primers
    4. Repairing damaged DNA
  22. Okazaki fragments are synthesized on which strand during DNA replication?

    1. Leading strand
    2. Lagging strand
    3. Template strand
    4. Coding strand
  23. Which enzyme seals the gaps between Okazaki fragments to form a continuous DNA strand?

    1. Helicase
    2. Primase
    3. Topoisomerase
    4. DNA ligase
  24. DNA polymerase has which type of proofreading activity to correct errors during replication?

    1. 5' to 3' exonuclease
    2. 3' to 5' exonuclease
    3. 5' to 3' polymerase
    4. 3' to 5' polymerase
  25. Which enzyme relieves supercoiling tension in the DNA ahead of the replication fork?

    1. Topoisomerase
    2. Helicase
    3. Ligase
    4. DNA polymerase

Application Questions

  1. You are designing a drug to inhibit an enzyme in the lysosome. You plan to deliver the drug inside a small liposome that will fuse with the cell membrane and release the drug into the cytosol. Which type of drug would achieve the highest concentration within lysosomes. Assume cytosol has a pH of 7.4 and lysosomes have a pH of 4.4.

    1. Drug A - weak acid pKa = 5.4
    2. Drug B - weak acid pKa = 6.5
    3. Drug C - weak base pKa = 8.4
    4. Drug D - weak base pKa = 9.4

    Show Explanation

  2. Which of the following is/are characteristic of a competitive antagonist?

    1. Inhibition by the antagonist is surmountable
    2. Potency depends on the concentration of competing agonists
    3. Inhibition typically displays use-dependence
    4. A and B

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  3. A 60 kg woman has a bacterial infection. You decide to administer an antibiotic that has a volume of distribution of 0.2 L/kg. The drug has a clearance of 200 ml/min. If you administer the drug by constant intravenous infusion, approximately how long will it take for the plasma concentration of the antibiotic to reach steady-state levels?

    1. 30 min
    2. 1 hr
    3. 3 hr
    4. 24 hr

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  4. A person who is houseless comes to your clinical and reports not having eaten in two day. The patient's serum glucose concentration is at the lower end of normal. Which source is currently allowing the patient to maintain serum glucose concentrations

    1. Amino acids
    2. Fatty acids
    3. Glycogen
    4. Ketone bodies

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  5. A 23-year old patient comes to your clinic with an irregular-shaped mole on their back that contains regions which differ in color. A biopsy and histological analysis indicate melanoma. The patient reports a history of tanning and extensive sun-exposure as a teenager. What type of mutation most likely led to development of the melanoma?

    1. Nucleotide deletion
    2. Nucleotide insertion
    3. Thymine dimer
    4. Nucleotide deamination

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  6. In the patient's cells, which process is actively involved in repairing the damage from UV light?

    1. Base excision repair
    2. Nucleotide excision repair
    3. Mismatch repair
    4. Homologous recombination

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  7. Insulin resistance increases the demands on insulin production by β-cells in the pancreas. What change would allow $beta;-cells to meet the increase in insulin production?

    1. Metaplasia
    2. Hyperplasia
    3. Atrophy
    4. Dysplasia

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  8. B-cell lymphoma is a cancer caused by the overproliferation of B-cells that secrete antibodies. A drug that inactivate which of the following proteins might be an effective treatment for B-cell lymphoma?

    1. Pex1
    2. Ire1
    3. Atg5
    4. SRP

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