Question 1

Which of the following best explains why the 1918 flu pandemic and the COVID-19 pandemic both required the use of quarantine and masking as public health measures?

Accepted Answer

Both pandemics involved viruses that could be spread by asymptomatic individuals, making it difficult to identify and isolate only sick people.

Question 2

A scientist wants to identify a bacterial species using ribotyping. Which of the following steps is performed FIRST in this process?

Accepted Answer

Amplifying rRNA genes using PCR with specific primers.

Question 3

During a PCR experiment, which temperature step allows primers to bind to the target DNA sequence?

Accepted Answer

Annealing at $$55^\circ C$$

Question 4

A researcher uses restriction enzymes in a ribotyping experiment. What is the main function of these enzymes?

Accepted Answer

To cut DNA at specific nucleotide sequences, generating fragments that differ between species.

Question 5

In gel electrophoresis, why do smaller DNA fragments move further down the gel than larger fragments?

Accepted Answer

Smaller fragments move more easily through the gel matrix due to their size.

Question 6

Which of the following best describes the natural function of CRISPR in bacteria?

Accepted Answer

It enables bacteria to defend themselves against bacteriophage infection by targeting and cutting foreign DNA.

Question 7

In a CRISPR gene editing experiment, what is the role of the guide RNA (gRNA)?

Accepted Answer

It directs the Cas9 enzyme to the specific DNA sequence to be cut.

Question 8

A CRISPR experiment disrupts the lacZ gene in bacteria. What result would you expect on X-gal plates if the gene is successfully disrupted and donor DNA is provided?

Accepted Answer

White colonies, indicating disrupted lacZ and successful repair.

Question 9

Which enzyme is essential for converting viral RNA into complementary DNA (cDNA) during RT-PCR testing for COVID-19?

Accepted Answer

Reverse transcriptase

Question 10

A COVID-19 RT-PCR test is performed. Which result indicates a positive test for SARS-CoV-2?

Accepted Answer

Fluorescence detected due to amplification of the N gene.

Question 11

A rapid strep test uses antibodies conjugated to colored beads. What is the principle behind a positive result in this test?

Accepted Answer

Antibodies on the beads bind to the Streptococcus pyogenes antigen, causing a visible colored line.

Question 12

Which of the following best describes the difference between a direct and an indirect ELISA?

Accepted Answer

Direct ELISA detects antigens using an enzyme-linked antibody, while indirect ELISA detects antibodies using an enzyme-linked secondary antibody.

Question 13

A blood smear shows a white blood cell with a multi-lobed nucleus and salmon-pink granules. Which cell type is this most likely to be?

Accepted Answer

Neutrophil

Question 14

Arrange the following white blood cells in order from most frequent to least frequent in normal human blood: Neutrophils, Basophils, Lymphocytes, Eosinophils, Monocytes.

Accepted Answer

Neutrophils \u003e Lymphocytes \u003e Monocytes \u003e Eosinophils \u003e Basophils

Question 15

Which of the following statements about vaccines and autism is supported by scientific evidence?

Accepted Answer

There is no scientific evidence supporting a link between vaccines and autism.

Question 16

A simulated epidemic in a class of 100 students results in 10 new cases of disease in one week. What is the incidence rate per 1,000 students?

Accepted Answer

$$\frac{10}{100} 	imes 1000 = 100$$

Question 17

Which of the following best describes a pathogen?

Accepted Answer

A microbe that causes disease.

Question 18

A urine culture is performed using the semi-quantitative streak method. If 312 colonies are counted on a plate inoculated with 0.001 mL of urine, what is the estimated concentration of bacteria in the original sample?

Accepted Answer

$$312 	imes 1000 = 312,000$$ CFU/mL

Question 19

MacConkey agar is used to culture urine samples. Which of the following results indicates the presence of Gram-negative, lactose-fermenting bacteria?

Accepted Answer

Growth of pink colonies.

Question 20

In the Snyder test for dental caries risk, what does a rapid color change from green to yellow indicate?

Accepted Answer

High acid production and increased risk for dental caries.

Microbiology Study Guide: Molecular Techniques, Immunoassays, Pathogens, and Clinical Applications

Study Guide - Practice Questions

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