=== QUESTIONS WITH ANSWERS ===

Question: Choose the correct direction of information flow in the central dogma

Answer: DNA → RNA → Protein

Question: A single nucleotide insertion in a coding region is most likely to cause:

Answer: A frameshift mutation

Question: Which molecule is most directly responsible for presenting extracellular (endocytosed) peptides to helper T cells?

Answer: MHC class II

Question: An infection acquired during a hospital stay is most precisely described as:

Answer: Nosocomial

Question: The protein shell that surrounds a virus’s nucleic acid is the:

Answer: Capsid

Question: Which method is designed to eliminate all forms of microbial life, including endospores, on heat-stable instruments?

Answer: Autoclaving

Question: Which category best describes a drug that prevents bacterial replication by halting growth but does not directly kill cells?

Answer: Bacteriostatic

Question: NAD+ is best described as a(n):

Answer: Electron carrier

Question: During which growth-curve phase do cells typically experience nutrient limitation while waste products accumulate?

Answer: Stationary phase

Question: Generation time in a bacterial culture refers to the:

Answer: Time required for one cell to divide into two

Question: Which adaptive immune cell type is the primary source of secreted antibodies?

Answer: Plasma cell

Question: Which complement outcome best matches MAC formation?

Answer: Direct lysis by pore formation

Question: Superantigens are dangerous because they:

Answer: Activate many T cells non-specifically, driving massive cytokine release

Question: For enveloped viruses, a common entry strategy into host cells is:

Answer: Fusion of viral envelope with host membrane

Question: In influenza A, hemagglutinin (HA) is primarily responsible for:

Answer: Binding to host receptors to initiate entry

Question: A major, abrupt change in influenza surface antigens caused by reassortment is called:

Answer: Antigenic shift

Question: Which statement about viral genomes is correct?

Answer: Viruses may carry either DNA or RNA as their genome

Question: Viruses are obligate intracellular parasites.

Answer: True

Question: Which control method uses heat to reduce microbial load in beverages without sterilization?

Answer: Pasteurization

Question: During translation, the molecule that base-pairs with codons on mRNA is:

Answer: tRNA

Question: A Gram-negative bacterium releases a fever-inducing molecule primarily when the cell dies and the outer membrane breaks...

Answer: Lipopolysaccharide (LPS) lipid A

Question: A bacterium produces an enzyme that clots plasma, helping it "wall off" from immune cells. This enzyme is:

Answer: Coagulase

Question: Which virulence strategy helps a pathogen avoid recognition by adaptive immunity by changing surface antigens over time?

Answer: Antigenic variation

Question: ID50 is best defined as the:

Answer: Dose that infects 50% of exposed subjects

Question: Which antiviral target would be irrelevant for bacteria because bacteria lack this process?

Answer: Viral uncoating

Question: The fact that multiple codons can specify the same amino acid is called:

Answer: Redundancy (degeneracy)

Question: In glycolysis, one glucose molecule yields how many pyruvate molecules?

Answer: 2

Question: A facultative anaerobe is best described as an organism that:

Answer: Grows with or without oxygen depending on conditions

Question: Which enzyme primarily relieves torsional strain (supercoiling) ahead of the replication fork in bacteria?

Answer: DNA gyrase (topoisomerase)

Question: Eukaryotic gene expression can be regulated at multiple steps; an example of post-transcriptional regulation is:

Answer: Alternative splicing of pre-mRNA

Question: Enzymes accelerate reactions primarily by:

Answer: Lowering activation energy

Question: Which statement best describes an amphibolic pathway?

Answer: Participates in both catabolism and anabolism

Question: Feedback inhibition most directly involves:

Answer: End product inhibiting an early enzyme in a pathway

Question: Which statement about endospores is most accurate?

Answer: They enable survival under harsh conditions

Question: In a phospholipid bilayer, the regions facing the aqueous environments are primarily ___ and the core is primarily ___.

Answer: Hydrophilic; hydrophobic

Question: Which human cell type is normally anucleate (lacks a nucleus) at maturity?

Answer: Red blood cell

Question: Unsaturated fatty acids typically:

Answer: Contain at least one C=C double bond

Question: The term describing how capable a microbe is of causing disease (as a yes/no property) is:

Answer: Pathogenicity

Question: Which metric refers to the proportion of a population that has a disease at a given time?

Answer: Prevalence

Question: High vaccination coverage in a community can indirectly protect unvaccinated individuals. This phenomenon is:

Answer: Herd immunity

Question: A Gram-negative bacterium is expected to have:

Answer: An outer membrane and a relatively thin peptidoglycan layer

Question: Mycobacterium tuberculosis is well adapted to survive inside macrophages.

Answer: True

Question: A neuraminidase inhibitor would most directly interfere with which influenza step?

Answer: Release of new virions from infected cells

Question: A vaccination that generates long-lasting memory B and T cells is an example of:

Answer: Artificially acquired active immunity

Question: Which statement best distinguishes exotoxins from endotoxin?

Answer: Exotoxins are secreted proteins; endotoxin is part of Gram-negative outer membrane

Question: A major reason many antivirals are difficult to design with high specificity is that viruses:

Answer: Use host-cell pathways for replication

Question: Breaking a disaccharide into two monosaccharides is a:

Answer: Decomposition (hydrolysis) reaction

Question: A point mutation converts a codon for an amino acid into a stop codon. This is a:

Answer: Nonsense mutation

Question: In bacteria, DNA transferred from one bacterium to another via a bacteriophage is:

Answer: Transduction

Question: A noncompetitive enzyme inhibitor typically reduces enzyme activity by:

Answer: Binding an allosteric site and reducing catalytic efficiency

Question: Facilitated diffusion differs from simple diffusion because facilitated diffusion:

Answer: Uses membrane proteins to move solutes down a gradient

Question: Which bond/interaction is most responsible for stabilizing protein secondary structure (α-helices and β-sheets)?

Answer: Hydrogen bonds between backbone atoms