mc practice questions

Practice Test – Advanced Microbiology (Multiple‑Choice Only)

Q1. Which modification in the T4 genome confers resistance to host restriction enzymes?
a) 5‑methylcytosine b) 5‑hydroxymethylcytosine c) pseudouridine d) N⁶‑methyladenine

  • glycosylation done to C in t4 genomes

  • add on a sugar, not OH (so not b)

  • not d → done to A, not c → done to isomer

Q2. In the canonical lytic cycle of a dsDNA bacteriophage, the step that immediately follows synthesis of viral genomes and proteins is:
a) Attachment to a new host cell b) Assembly of capsid and tail components c) Release by host‑cell lysis d) DNA packaging into pre‑formed heads

  • b or d - chose b bc need capsid formed to package DNA

Q3. High intracellular levels of which λ‑phage regulator favor entry into lysogeny by blocking transcription from promoter PL?
a) Cro b) cII c) cI d) N

  • favor lysogeny by blocking transc from Pl

  • lysogeny : ci :: lytic : cro but also cii promote lysogeny

  • ci bind to operator seq - or3 and 2 make up pl

Q4. The retroviral gene that encodes the enzyme that converts the viral RNA genome into DNA is:
a) gag b) pol c) env d) vif

  • need to review pol vs gag cause i can’t for the life of my remember gag encodes → pol encodes rt, protease, and integrase

Q5. Which statement about the M13 filamentous phage life cycle is FALSE?
a) Infection does not lyse the host cell b) The genome is single‑stranded DNA c) Replication proceeds via a rolling‑circle mechanism d) Progeny are released by host‑cell burst

  • progeny are secreted from M13 and slow metabolic activities 

Q6. The increase in copy number of bacteriophage Mu during lysogeny is achieved by:
a) Conservative replication b) Site‑specific recombination c) Replicative transposition d) Headful DNA packaging