Q: Which equation correctly represents the therapeutic index?

$$\text{Therapeutic Index} = \frac{\text{Toxic Dose}}{\text{Effective Dose}}$$

Question 1

Which of the following best describes the mechanism of action of beta-lactam antibiotics?

Accepted Answer

They inhibit cell wall cross-linking, preventing peptidoglycan formation.

Question 2

A patient is prescribed Augmentin for a bacterial infection. Which statement correctly explains why this combination is more effective than amoxicillin alone?

Accepted Answer

Clavulanic acid inhibits beta-lactamase enzymes, allowing amoxicillin to inhibit cell wall synthesis.

Question 3

Which of the following mechanisms is NOT a way bacteria develop resistance to antibiotics?

Accepted Answer

Increasing the drug's therapeutic index.

Question 4

Why are fungal and protozoal infections generally harder to treat than bacterial infections?

Accepted Answer

Their cells are structurally and functionally similar to human cells.

Question 5

A researcher wants to clone a eukaryotic gene in bacteria. Which enzyme is used to convert mRNA into cDNA?

Accepted Answer

Reverse transcriptase

Question 6

Which of the following statements about selective toxicity is TRUE?

Accepted Answer

Drugs with high selective toxicity target features unique to microbes, such as peptidoglycan and 70S ribosomes.

Question 7

Which of the following is a major reason for the rise in antibiotic resistance?

Accepted Answer

Overuse and misuse of antibiotics, including incomplete courses and agricultural use.

Question 8

A scientist uses restriction enzymes to cut both a plasmid and a gene of interest. What is the purpose of using the same restriction enzyme for both?

Accepted Answer

To ensure the plasmid and gene have compatible sticky ends for complementary base pairing.

Question 9

Which equation correctly represents the therapeutic index?

Accepted Answer

$$	ext{Therapeutic Index} = \frac{	ext{Toxic Dose}}{	ext{Effective Dose}}$$

Question 10

In the blue-white screening procedure, what color colonies indicate successful insertion of a gene into the plasmid?

Accepted Answer

White colonies

Question 11

Which of the following drugs blocks DNA replication by inhibiting DNA gyrase?

Accepted Answer

Quinolones

Question 12

A patient is infected with Mycobacterium tuberculosis. Which drug is specifically used to target this organism?

Accepted Answer

Isoniazid, which blocks mycolic acid synthesis.

Question 13

Which of the following statements about plasmids used in gene cloning is FALSE?

Accepted Answer

Plasmids must lack antibiotic resistance genes to prevent selection.

Question 14

A culture of E. coli is transformed with a plasmid containing an ampicillin resistance gene. If plated on ampicillin-containing medium, what will happen?

Accepted Answer

Only bacteria with the plasmid will grow.

Question 15

Which of the following is NOT a step in the Southern blotting technique?

Accepted Answer

Addition of heat-stable DNA polymerase.

Question 16

Which of the following statements correctly differentiates a genomic library from a cDNA library?

Accepted Answer

A genomic library contains fragments of all DNA in an organism’s genome; a cDNA library contains only coding sequences of eukaryotic genes (no introns).

Question 17

Which of the following is NOT a purpose of genetic modification?

Accepted Answer

To remove antibiotic resistant plasmids from bacteria.

Question 18

A scientist wants to amplify a small gene using PCR. After 3 cycles, how many double-stranded DNA molecules will be produced?

Accepted Answer

$$8$$

Question 19

Which of the following is a plausible consequence of widespread use of antibiotics in animal feed?

Accepted Answer

Resistant bacteria are promoted and can transfer to humans.

Question 20

Which of the following statements about antiviral drugs is TRUE?

Accepted Answer

Viruses are hard to treat because they use host machinery and have few drug targets.

Antimicrobial Drugs, Resistance, and Recombinant DNA Technology

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