Question

36.

Antimicrobial resistance mechanisms include

	A.	removing efflux pumps from the cell membrane.
	B.	modifying or reducing the amount of the target of the drug.
	C.	inhibition of protein synthesis in the microbe.
	D.	preventing attachment of the microbe.
	E.	All of the above are antimicrobial resistance mechanisms.

37.

Which of the following is TRUE about antibiotic interaction?

	A.	Taking two antibiotics together may neutralize the effects of both.
	B.	Synergism occurs when two antibiotics work better together than alone.
	C.	Antagonism occurs when two antibiotics work better alone than together.
	D.	A, B, and C are true.
	E.	none of the above is true.

39.

The mechanism of action of erythromycin is

	A.	inhibition of cell wall synthesis.
	B.	disruption of cytoplasmic membranes.
	C.	inhibition of a metabolic pathway.
	D.	inhibition of protein synthesis.
	E.	inhibition of nucleic acid synthesis.

43.

in general, exotoxins cause a fever; endotoxins do not.

True

False

46.

The DNA sequence of a portion of gene in a wild-type organism is TTACCAATATCACCC, and the corresponding peptide sequence is Asn-Gly-Tyr-Ser-Gly. The corresponding gene fragment in a phenotypic variant of the organism is TTACCAACATCACCC and the peptide sequence is Asn-Gly-Cys-Ser-Gly. This is an example of a ________ mutation (type) resulting in a ________ mutation (effect).

	A.	insertion; nonsense
	B.	base substitution; nonsense
	C.	deletion; missense
	D.	base substitution; silent
	E.	base substitution; missense

Answer 1

36.Antimicrobial resistance mechanisms include

Correct option: B. modifying or reducing the amount of the target of the drug

Justification: This is correct because modification of target of the drug will not allow drug to kill microbes and lead to antimicrobial resistance. Even reducing the amount will not result in effective action of drug to kill microbes but manifests towards  antimicrobial resistance

37.Which of the following is TRUE about antibiotic interaction?

Correct option: B. Synergism occurs when two antibiotics work better together than alone.

Justification: This is correct statement because synergistic effect means effect of combination of antibiotic  is more than single antibiotic  alone whereas in antagonism, one antibiotic inhibit or nullify the action of other antibiotic.

Taking two antibiotics together may neutralize the effects of both is not true always.

Antagonism occurs when two antibiotics work better alone than together is not correct statement.

39.The mechanism of action of erythromycin is

Correct option: D. inhibition of protein synthesis

Justification- This is the correct option because erythromycin specifically binds to the 50 S subunit of the ribosome and inhibit the protein synthesis in bacteria.

43.in general, exotoxins cause a fever; endotoxins do not.

Correct option: False

Justification: Endotoxins are pyrogenic , cause fever whereas exotoxins are usually not pyrogenic and it doesnot cause fever.

46.The DNA sequence of a portion of gene in a wild-type organism is TTACCAATATCACCC, and the corresponding peptide sequence is Asn-Gly-Tyr-Ser-Gly. The corresponding gene fragment in a phenotypic variant of the organism is TTACCAACATCACCC and the peptide sequence is Asn-Gly-Cys-Ser-Gly. This is an example of a _base_substitution______ mutation (type) resulting in a __missense______ mutation (effect).

Correct option: E. base substitution; missense

Justification- Wild type DNA sequence:  TTA CCA ATA TCA CCC

Variant DNA sequence:   TTA CCA ACA TCA CCC

In both given DNA sequence, we can see that in ATA codon T base is substituted with base C at same position in variant codon ACA. So, this denotes the base substitution method.

In missense mutation codon code for different amino acid after base substitution whereas in silent mutation codon code for same amino and in silent muation, codon codes for stop codon instead of amino acid. In this case, Tyrosine of wild type is replaced by Cysteine amino acid after base substitution which confirm that this is missense mutation.