Question 1

Which of the following statements best describes a unique feature of Archaea compared to Bacteria and Eukarya?

Accepted Answer

Archaea have membrane lipids with ether linkages rather than ester linkages.

Question 2

A patient presents with a bacterial infection. The bacteria are rod-shaped, have a thick peptidoglycan layer, and retain the crystal violet stain. Which of the following best describes these bacteria?

Accepted Answer

Gram-positive bacilli

Question 3

Which of the following best explains why viruses are not classified within the three domains of life?

Accepted Answer

Viruses lack ribosomes and cannot carry out metabolism independently.

Question 4

During glycolysis, what is the net gain of ATP molecules per molecule of glucose metabolized?

Accepted Answer

$$2$$

Question 5

Which of the following best distinguishes fermentation from aerobic respiration in bacteria?

Accepted Answer

Fermentation produces lactic acid or ethanol as end products, while aerobic respiration produces $$\mathrm{CO_2$}$$ and $$\mathrm{H_2O}.$$

Question 6

A bacterium is classified as a chemoheterotroph. Which of the following best describes its energy and carbon sources?

Accepted Answer

Organic compounds for both energy and carbon

Question 7

A microbiologist is culturing bacteria that grow best at $$37^\circC $$but can survive at $$25^\circC $$and $$45^\circC. $$What is the term for $$37^\circC in $$this context?

Accepted Answer

Optimum growth temperature

Question 8

Which of the following best describes the function of bacterial endospores?

Accepted Answer

They allow bacteria to survive harsh environmental conditions.

Question 9

Which enzyme is responsible for synthesizing new DNA strands during bacterial DNA replication?

Accepted Answer

DNA polymerase

Question 10

A scientist uses PCR to amplify a segment of DNA. Which of the following is NOT required for the PCR reaction?

Accepted Answer

DNA ligase

Question 11

Which of the following statements about the lytic and lysogenic cycles of bacteriophages is correct?

Accepted Answer

The lytic cycle results in immediate destruction of the host cell, while the lysogenic cycle integrates viral DNA into the host genome.

Question 12

Which of the following is a function of the complement system in innate immunity?

Accepted Answer

Opsonization, which enhances phagocytosis of pathogens

Question 13

Which of the following best describes the role of antigen-presenting cells (APCs) in adaptive immunity?

Accepted Answer

APCs present processed antigens on $$\mathrm{MHC~II}$$ molecules to helper T cells.

Question 14

Which of the following is a correct pairing of antibody class and its primary function?

Accepted Answer

$$\mathrm{IgA}$$: Found in mucosal secretions and protects body surfaces

Question 15

A patient receives a vaccine containing inactivated virus. Which type of immunity is being induced?

Accepted Answer

Artificially acquired active immunity

Question 16

Which of the following best explains why Gram-negative bacteria are generally more resistant to antibiotics than Gram-positive bacteria?

Accepted Answer

Gram-negative bacteria possess an outer membrane that restricts entry of many drugs.

Question 17

A patient with HIV/AIDS is at increased risk for opportunistic infections. Which immune cells are primarily depleted in this disease?

Accepted Answer

Helper T cells ($$\mathrm{CD4^+})$$

Question 18

Which of the following is an example of a Type I hypersensitivity reaction?

Accepted Answer

Allergic reaction to pollen resulting in hay fever

Question 19

Which of the following best describes the principle of the ELISA (enzyme-linked immunosorbent assay) test?

Accepted Answer

It detects the presence of specific antigens or antibodies using enzyme-labeled antibodies and a color change.

Question 20

A hospital is testing a new diagnostic test for a rare bacterial infection. The test correctly identifies 95 out of 100 infected patients and correctly identifies 850 out of 900 uninfected patients. What is the sensitivity of the test?

Accepted Answer

$$\frac{95}{100} = 95\%$$

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