Question 1

Which of the following best describes a chemoheterotroph?

Accepted Answer

An organism that obtains both energy and carbon from organic compounds

Question 2

A bacterium that grows best at 37$$^\circC $$and is inhibited at temperatures below 20$$^\circC or $$above 45$$^\circC is $$classified as a:

Accepted Answer

Mesophile

Question 3

Which of the following best describes a neutrophile?

Accepted Answer

A bacterium that grows best at neutral pH (around 7)

Question 4

Which of the following media is both selective and differential, and is commonly used to distinguish lactose fermenters from non-lactose fermenters among Gram-negative bacteria?

Accepted Answer

MacConkey Agar (MAC)

Question 5

A microbiologist observes colonies with a greenish discoloration around them on a Blood Agar Plate (BAP). What type of hemolysis is this, and what does it indicate?

Accepted Answer

Alpha hemolysis; partial lysis of red blood cells

Question 6

Which of the following conditions are provided by incubators to support bacterial growth?

Accepted Answer

Temperature, humidity, and oxygen concentration

Question 7

Which of the following is an advantage of automated biochemical identification methods over multi-test systems?

Accepted Answer

Automated methods provide faster results and reduce human error

Question 8

Which of the following is a main advantage of gene probes over routine biochemical identification methods?

Accepted Answer

Gene probes can detect non-culturable organisms

Question 9

A silent mutation in a bacterial gene is best described as:

Accepted Answer

A mutation that does not change the amino acid sequence of the protein

Question 10

Which DNA transfer mechanism involves the direct transfer of DNA from one bacterium to another via a pilus?

Accepted Answer

Conjugation

Question 11

Insulin and human growth hormone are produced by genetically engineered bacteria using which DNA transfer mechanism?

Accepted Answer

Transformation

Question 12

Which of the following best describes a 'superbug' in a hospital setting?

Accepted Answer

A bacterium that is resistant to multiple antibiotics due to acquired resistance genes

Question 13

E. coli O157:H7 acquired its ability to produce toxins through which genetic transfer mechanism?

Accepted Answer

Transduction

Question 14

Which of the following best describes the main difference between the elementary body and the reticulate body in the Chlamydia life cycle?

Accepted Answer

The elementary body is infectious and non-replicative, while the reticulate body is metabolically active and replicates

Question 15

Which chlamydial infection is characterized by the development of a bubo?

Accepted Answer

Lymphogranuloma venereum

Question 16

A patient presents with a painless chancre at the site of infection. Which stage of syphilis is this, and what is the causative organism?

Accepted Answer

Primary syphilis; Treponema pallidum pallidum

Question 17

Which of the following is a main long-term complication of trachoma in babies?

Accepted Answer

Blindness

Question 18

A Gram-negative rod grows on Hektoen Enteric (HE) agar and produces black colonies. What does this indicate about the organism?

Accepted Answer

It does not ferment lactose but produces H$$_2S$$

Question 19

Which of the following best describes the use of serological tests in bacterial identification?

Accepted Answer

They detect specific antigens or antibodies associated with bacteria

Question 20

A Gram-positive coccus grows on CNA agar, shows beta hemolysis on BAP, and does not grow on MAC. What is the most likely identity of this organism?

Accepted Answer

Staphylococcus aureus

Microbial Nutrition, Growth, Genetics, and Selected Pathogens: Study Notes

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