Question 1

Which scientist is credited with definitively disproving the theory of spontaneous generation through his swan-neck flask experiment, and what was the main conclusion of his work?

Accepted Answer

Louis Pasteur; he demonstrated that microorganisms do not arise from nonliving matter but from other microorganisms.

Question 2

A patient is diagnosed with tuberculosis. According to Koch’s postulates, which of the following steps must be performed to confirm that Mycobacterium tuberculosis is the causative agent?

Accepted Answer

Demonstrate that the bacterium can be grown in pure culture and causes the same disease when introduced into a healthy host.

Question 3

Which of the following best describes an emerging infectious disease, and why are such diseases significant in public health?

Accepted Answer

A disease that is newly identified or increasing in incidence; they are significant because they can rapidly spread and challenge existing medical practices.

Question 4

During a Gram stain, a student forgets to apply the decolorizer (alcohol). What will be the appearance of both Gram-positive and Gram-negative bacteria under the microscope?

Accepted Answer

Both will appear purple.

Question 5

Which of the following statements correctly compares prokaryotic and eukaryotic cells?

Accepted Answer

Both prokaryotes and eukaryotes have ribosomes, but only eukaryotes have a nucleus.

Question 6

A bacterium is described as 'lophotrichous.' What does this indicate about its flagella?

Accepted Answer

It has a tuft of flagella at one or both ends.

Question 7

Which component is found in the cell wall of Gram-negative bacteria but not in Gram-positive bacteria, and what is its significance?

Accepted Answer

Lipopolysaccharide (LPS); it contributes to the toxicity and immune response during infection.

Question 8

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

Accepted Answer

It protects bacteria from phagocytosis and helps in adherence to surfaces.

Question 9

Which organelle is responsible for ATP production in eukaryotic cells, and what theory explains its evolutionary origin?

Accepted Answer

Mitochondrion; endosymbiotic theory

Question 10

A microbiologist wants to count the number of viable bacteria in a water sample. Which method should they use, and what is a limitation of this method?

Accepted Answer

Direct microscopic count; it cannot distinguish between live and dead cells.

Question 11

Which phase of the bacterial growth curve is characterized by the equation $$N = N_0$ 	imes 2^n$$, and what does each variable represent?

Accepted Answer

Log (exponential) phase; $$N is $$the final cell number, $$N_0 is $$the initial cell number, $$n is $$the number of generations.

Question 12

A bacterium is classified as a 'facultative anaerobe.' Which of the following best describes its growth in the presence and absence of oxygen?

Accepted Answer

It grows in both the presence and absence of oxygen, but grows better with oxygen.

Question 13

Which of the following best describes the difference between sterilization, disinfection, and sanitation?

Accepted Answer

Sterilization destroys all forms of microbial life, disinfection destroys most pathogens on inanimate objects, sanitation reduces microbial counts to public health standards.

Question 14

Which heat-based method is most effective for sterilizing heat-stable laboratory media and surgical instruments, and what are the typical conditions used?

Accepted Answer

Autoclaving; $$121^\circ C at 15 $$psi for 15 minutes

Question 15

A hospital is experiencing an outbreak of MRSA (Methicillin-resistant Staphylococcus aureus). Which of the following control measures would be most effective in preventing the spread of this pathogen?

Accepted Answer

Using aseptic technique and proper hand hygiene among staff.

Question 16

Which of the following statements about biofilms is correct?

Accepted Answer

Biofilms are communities of microorganisms attached to surfaces, often resistant to antibiotics.

Question 17

Which of the following best describes the function of the Golgi apparatus in eukaryotic cells?

Accepted Answer

It modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

Question 18

A microbiologist is using a phase contrast microscope to observe live, unstained cells. What is the main advantage of this technique?

Accepted Answer

It increases the contrast of transparent specimens without staining, allowing observation of living cells.

Question 19

Which of the following statements about group translocation in bacteria is correct?

Accepted Answer

It involves the chemical modification of a substance as it is transported into the cell.

Question 20

Which of the following best describes the role of lyophilization in microbiology?

Accepted Answer

It is a method for long-term preservation of microbial cultures by freeze-drying.

Step-by-Step Study Guidance for Microbiology Exam 1 Review

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