Practice Exam PDF

 SECTION A Recommended maximum total time for this section: 80 minutes Answers must be completed on the multiple-choice answer sheet For each question, use pencil to fill the circle corresponding to the...

 SECTION A Recommended maximum total time for this section: 80 minutes Answers must be completed on the multiple-choice answer sheet For each question, use pencil to fill the circle corresponding to the answer option that is most correct. Each question in this section is worth 2 marks and should take 2 minutes or less to complete. Question 1 This genetic code specifies the amino acid sequences of proteins encoded by human nuclear genes. The coding portion of an mRNA starts with the sequence: 5’-AUGUAUAGAUGACCG-3’. If a G was inserted between the first and second codons, what would the last amino acid be within the mutant peptide? A. Valine (abbreviated Val) B. Proline (abbreviated Pro) C. Tyrosine (abbreviated Tyr) D. Arginine (abbreviated Arg) E. Methionine (abbreviated Met) 2 Question 2 The coding portion of an mRNA starts with the sequence 5’-AUGUAUAGAGACCGA-3’. What is the sequence of the corresponding section of the template strand of the DNA? (5’ to 3’) A. 5’-TACATATCTCTGGCT-3’ B. 5’-TCGGTCTCTATACAT-3’ C. 5’-ATGTATAGAGACCGA-3’ D. 5’-UCGGUCUCUAUACAU-3’ E. 5’-UACAUAUCUCUGGCU-3’ Question 3 Which statement best describes the molecular basis of most Li Fraumeni cases? A. Most mutations enhance the activity of the translated protein B. Mutant cells have enhanced ability to detect and respond to DNA damage C. Most mutations abolish expression of the encoded protein in patients’ cells D. Inclusion of mutant monomers within a transcription factor abolishes its function E. Patients have homozygous or compound heterozygous mutations in the disease-associated gene Question 4 What is a key symptom of patients with a syndrome caused by SNORD116 mutations? A. Obesity B. Frequent cancers C. Happy personality D. Poor lung function E. Aortic dilation and rupture Question 5 Which technique involves labelling each chromosome with a different colour? A. Southern blotting B. Sanger sequencing C. Spectral karyotyping D. Tissue in-situ hybridisation E. Restriction fragment length polymorphism 3 Question 6 Which of these genes, when mutated, causes speech defects? A. p53 B. LCT C. ALAS2 D. FOXP2 E. EPAS-1 Question 7 Which statement best describes the molecular basis of most cystic fibrosis cases? A. Patients’ cells cannot export fibrillin B. Patients’ cells cannot export chloride C. No protein is produced from mutant alleles D. Patients’ cells cannot metabolise phenylalanine E. One wild type allele does not produce enough protein to preserve lung function Question 8 Which is composed of linear DNA? A. A plasmid B. An E. coli chromosome C. A human X chromosome D. A prokaryotic chromosome E. A human mitochondrial chromosome Question 9 During genetic screening, a patient is found to have the HER-2 gene amplified. How might this impact treatment of this patient? A. Increased dosage with Herceptin B. Decreased dosage with Herceptin C. Increased dosage with anti-depressant medication D. Decreased dosage with anti-depressant medication E. None of the above 4 Question 10 Which mutation would be most likely to cause a dominant phenotype? (2 min) A. A null mutation B. A loss-of-function mutation C. A mutation that increases the number of repeats at an STR locus D. A mutation to a protease that results in it cleaving different proteins E. A mutation that leads to the encoded protein being rapidly degraded Question 11 Which of the following viral vectors used in gene therapy insert the therapeutic gene into the host genome? A. Adeno-associated virus B. Herpes simplex virus C. Lentivirus D. Adenovirus E. Vaccinia virus Question 12 When might a patient with a genetic disease be effectively treated by a drug that promotes exon-skipping? A. When the patient has cystic fibrosis B. When the patient has Fragile-X syndrome C. When the patient has Becker Muscular Dystrophy D. When the disease is caused by a frameshift mutation E. When the disease is caused by a whole-gene deletion Question 13 When is a mutation most likely to be inherited by future generations? A. DNA polymerase incorporates the wrong nucleotide during replication B. A mis-incorporated base is replaced by base excision repair in a somatic cell C. A single-strand break in a germ-line cell is repaired by homologous recombination D. A double-strand break in a somatic cell is repaired by non-homologous end-joining E. A double-strand break in a germ-line cell is repaired by non-homologous end-joining 5 Questions 14-16 Read the text and consider the diagram, then use this information to answer questions 14-16. The pedigree below is from a family in which multiple members have Down syndrome. Question 14 What symptom(s) would the affected family members experience? A. Intellectual disability B. Very pale skin and hair C. Tall with unusually flexible joints D. Rashes and impaired liver function E. Equivalent lifespan to unaffected relatives Question 15 What is the most likely genetic cause of the symptoms experienced by the affected individuals? A. A translocation B. A single copy a chromosome C. A deletion within a chromosome D. An inversion within a chromosome E. Three separate copies of a chromosome Question 16 Which is the most common cause of Down syndrome? A. Inheriting fused chromosomes B. Non-disjunction of an autosome C. Non-disjunction of the X chromosome D. Inheriting chromosomes bearing deletions E. Inheriting chromosomes bearing insertions 6 Question 17 Which of the following is NOT a genetic approach to treating disease? A. Genetic modification of patient cells and/or DNA B. Screening of patient genes to select appropriate drugs and dosages C. Production of antibodies and vaccines using recombinant DNA technology D. Engineering an artificial aid to restore bodily function impaired by genetic mutation E. Screening efficacy of a recombinantly produced protein therapy in genetically modified animals Question 18 How should you interpret a LOD score of one? A. The marker is within the gene B. The marker is close to the gene C. The marker is distant from the gene D. All participants in the study were recombinant E. No participants in the study were recombinant Question 19 Which gene has an allele carried by many Tibetans that their ancestors inherited from Denisovans? A. p53 B. LCT C. PAH D. FOXP2 E. EPAS-1 Question 20 Which is true of lactose tolerance? A. Lactose tolerance is dominant B. Most adult humans are lactose tolerant C. Lactose tolerance occurs due to haploinsufficiency D. Most non-human mammals can comfortably drink milk as adults E. Lactose tolerance is caused by a change in the amino acid sequence of lactase 7 Question 21 What is the molecular basis of oculocutanous albinism type 2? A. An inability to convert tyrosine into melanin B. An inability to convert melanin into tyrosine C. An inability to import tyrosine into mitochondria D. An inability to import melanin into melanosomes E. An inability to import tyrosine into melanosomes Question 22 Which of the following methods is NOT used in the process of generating forensic DNA profiles? A. Spectral karyotyping B. Polymerase Chain Reaction (PCR) C. Short Tandem Repeat (STR) Analysis D. Variable Number Tandem Repeat (VNTR) Analysis E. Restriction Fragment Length Polymorphism (RFLP) Question 23 A boy with Fragile-X syndrome inherited the disease from his unaffected mother. What would her genotype most likely be? A. Both FMR1 alleles have 40 repeats B. Both FMR1 alleles have 300 repeats C. Homozygous for null mutations in FMR1 D. One FMR1 allele has 70 repeats, the other has 40 repeats E. One FMR1 allele has 300 repeats, the other has 40 repeats Question 24 Which feature do plasmids and eukaryotic chromosomes share? A. They both contain telomeres B. Their DNA is single-stranded C. Their DNA is wound around histones D. Their replication starts at multiple sites E. During replication, one strand is copied in short stretches 8 Question 25 Which technique can change the nucleotide sequence of a gene? A. PCR B. RT-PCR C. CRISPR-Cas9 D. Sanger sequencing E. Spectral karyotyping Question 26 Mutations in the mitochondrial genome tend to affect the ability of cells to generate energy due to: A. impacting the packaging of DNA in the mitochondria B. impacting the ability of cells copy DNA and the nucleus C. impacting DNA repair mechanisms in the mitochondria D. impacting the ability of cells to segregate cellular contents during cell division E. impacting function of the electron transport chain and oxidative phosphorylation Question 27 Which would be most likely to be true of a tetraploid plant? (2 min) A. It would be seedless B. It would not be viable C. It would create haploid gametes D. It could not interbreed with diploid relatives to produce fertile offspring E. It could have resulted from mating between diploid and tetraploid plants Question 28 Which is true of the X-linked recessive mode of inheritance? A. Phenylketonuria exhibits it B. Lactose tolerance exhibits it C. Almost all affected individuals are male D. Almost all affected individuals are female E. A disease involving mutations in the FMR1 gene exhibits it 9 Question 29 Which disease can be prevented by avoiding foods containing a particular amino acid? A. Cystic fibrosis B. Phenylketonuria C. Marfan syndrome D. Oculocutaneous albinism type 2 E. X-linked dominant protoporphyria Question 30 What would happen if a homozygous deletion removed a gene encoding an amino-acyl tRNA synthetase? A. Introns would be translated B. Generation of mRNAs would be impaired C. Ribosome subunits would not assemble properly D. The wrong amino acids would be attached to tRNAs E. One amino acid would not be attached to any tRNAs Question 31 What symptom would be most likely to be experienced by a hypothetical woman who is heterozygous for null mutations in her CFTR and OCA2 genes? A. Pale skin B. No symptoms C. Mental retardation D. Increased cancer risk E. Deteriorating lung function Question 32 What is the mode of inheritance of Marfan syndrome? A. Mitochondrial B. X-linked recessive C. X-linked dominant D. Autosomal recessive E. Autosomal dominant 10 Questions 33-34 Use the STR profile shown below to answer questions 33-34. Question 33 How many STR loci have been used to create the profile? A. 4 B. 10 C. 16 D. 26 E. 372 Question 34 How many STR loci are heterozygous in this profile? A. 4 B. 10 C. 16 D. 26 E. 372 11 Question 35 Which is a piece of evidence that helped to identify the first self-replicating biomolecule on earth? A. Genes usually consist of DNA B. A subset of lipids can synthesise proteins C. Some proteins can create copies of themselves D. Specific DNA sequences can create copies of themselves E. Modern RNAs can have enzymatic activities and can encode proteins See next page for Section B 12  SECTION B Recommended total time: 40 minutes Answers to be completed in a script book Each question in this section is worth 7 marks and should take around 7 minutes to complete. Question 36 The process of transcription uses genetic information from one biomolecule to create a different biomolecule. Name the starting biomolecule (1 mark) and the one that is produced by transcription (1 mark). Describe one way that eukaryotic transcription can be boosted or suppressed (2 marks). List three modifications that occur in eukaryotic cells to the biomolecule produced via transcription (3 marks). Question 37 During which phase of the cell cycle is DNA replicated (1 mark)? Name the enzyme and building blocks that are used to extend a new strand of DNA (2 marks). Which end of the new chain is extended (1 mark)? What molecule is released each time one of these components is added to the chain (1 mark)? Sanger sequencing uses variants of these components. What are they, and what happens when they are incorporated into the new DNA strand (2 marks)? Question 38 Describe the process of generating an STR profile (2 marks). How is an individual identified using an STR profile? (2 marks). What issues can complicate accurate identification of an individual using STR analysis? (3 marks). Question 39 What is X inactivation (4 marks)? Describe a scenario in which skewed X inactivation may cause an individual to experience symptoms not expected based on their genotype (3 marks). Question 40 Knowledge of the molecular basis of genetic diseases has enabled the development of “molecularly targeted” treatments to address the specific molecular defects responsible for some genetic conditions. Name an inherited disease for which molecularly-targeted therapies have been developed (1 mark). What gene causes this disease when mutated (1 mark)? What is its mode of inheritance (2 marks)? Explain how a targeted drug for this disease works (3 marks). END OF EXAM 13