Question 1

Which of the following best describes a Type I hypersensitivity reaction?

Accepted Answer

It is an immediate, antibody-mediated reaction involving IgE and mast cell degranulation.

Question 2

A patient receives a mismatched blood transfusion and develops a severe reaction. Which type of hypersensitivity is this, and what is the primary mechanism?

Accepted Answer

Type II; antibody-mediated cytotoxicity

Question 3

Which of the following is the most sensitive diagnostic test for early HIV infection?

Accepted Answer

PCR for HIV RNA

Question 4

Which of the following statements about attenuated vaccines is correct?

Accepted Answer

They contain live, weakened microorganisms that can replicate and induce strong immunity.

Question 5

During pasteurization, which of the following equations represents the relationship between thermal death time ($TDT$), temperature ($T$), and microbial death rate ($k$)?

Accepted Answer

$\log N = \log N_0 - kT$

Question 6

Which of the following antimicrobial drugs acts by inhibiting cell wall synthesis?

Accepted Answer

Penicillin

Question 7

A hospital is deciding between using phenol and alcohol as disinfectants. Which factor is most important in determining their effectiveness?

Accepted Answer

The presence of organic matter

Question 8

Which of the following best explains the function of clavulanic acid in Augmentin?

Accepted Answer

It inhibits beta-lactamase enzymes, protecting amoxicillin from degradation.

Question 9

Which step in the polymerase chain reaction (PCR) is responsible for separating double-stranded DNA into single strands?

Accepted Answer

Denaturation

Question 10

In the nitrogen cycle, which process is responsible for converting atmospheric nitrogen ($N_2$) into ammonia ($NH_3$)?

Accepted Answer

Nitrogen fixation

Question 11

A patient develops a rash 48 hours after exposure to poison ivy. Which type of hypersensitivity is this, and what is the main immune cell involved?

Accepted Answer

Type IV; T cells

Question 12

Which of the following is a major advantage of using DNA or mRNA vaccines over traditional whole-agent vaccines?

Accepted Answer

They can be rapidly designed and produced for emerging pathogens.

Question 13

Which of the following best describes the mechanism of action of quinine derivatives in treating malaria?

Accepted Answer

Disruption of heme detoxification in Plasmodium parasites

Question 14

Which of the following statements about the use of the Mantoux test for tuberculosis is correct?

Accepted Answer

A positive result may indicate prior exposure, vaccination, or latent infection.

Question 15

Which of the following is the correct order of microorganisms from most to least resistant to disinfectants?

Accepted Answer

Prions > Endospores > Mycobacteria > Gram-negative bacteria

Question 16

Which of the following best explains why the use of antibiotics in animal feed can contribute to antibiotic resistance in human pathogens?

Accepted Answer

Antibiotics in animal feed select for resistant bacteria, which can transfer resistance genes to human pathogens.

Question 17

Which of the following best describes the function of T4 ligase in recombinant DNA technology?

Accepted Answer

It joins DNA fragments by forming phosphodiester bonds.

Question 18

A laboratory is using an indirect ELISA to detect antibodies against a virus. Which of the following best describes the process?

Accepted Answer

Antigen is bound to the well, patient antibody binds, and enzyme-linked secondary antibody detects the bound antibody.

Question 19

Which of the following is a key feature of the cutaneous form of anthrax caused by Bacillus anthracis?

Accepted Answer

It is characterized by a painless black eschar at the site of infection.

Question 20

Which of the following best describes the role of the enzyme DNA polymerase in PCR?

Accepted Answer

It synthesizes new DNA strands by adding nucleotides to primers.

Disorders Associated With The Immune System#4

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