Question 1

Which of the following statements best explains why ribosomal RNA (rRNA) is used to determine phylogenetic relationships among microorganisms?

Accepted Answer

rRNA is universally conserved among all living organisms and accumulates mutations slowly, making it suitable for comparing evolutionary relationships.

Question 2

A scientist isolates a microorganism from a hot spring with a temperature of 90°C and high acidity. Which group is this organism most likely to belong to?

Accepted Answer

Archaea

Question 3

Which of the following is NOT a characteristic shared by all living microbial cells?

Accepted Answer

Differentiation: synthesis of new substances or structures that modify the cell

Question 4

Which of the following best describes a plasmid?

Accepted Answer

A circular, extrachromosomal DNA molecule found in many Bacteria and Archaea that may confer selective advantages such as antibiotic resistance.

Question 5

Which of the following statements about the domains of life is correct?

Accepted Answer

Archaea are more closely related to Eukarya than to Bacteria.

Question 6

Which of the following is a positive impact of microorganisms on agriculture?

Accepted Answer

Nitrogen fixation by bacteria, which enriches soil fertility

Question 7

A microbiologist wants to observe the surface structure of a bacterial cell at very high magnification. Which microscopy technique should they use?

Accepted Answer

Scanning electron microscopy (SEM)

Question 8

Which of the following best explains why differential stains, such as the Gram stain, are important in microbiology?

Accepted Answer

They distinguish between different types of cell wall structures, aiding in bacterial classification.

Question 9

Which of the following is a correct comparison between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have DNA enclosed in a nucleus, while prokaryotic cells have DNA in a nucleoid region.

Question 10

Which of the following best describes the main contribution of Robert Koch to microbiology?

Accepted Answer

He developed techniques for obtaining pure cultures and established the link between microbes and infectious diseases.

Question 11

A sample contains a mixture of living and dead bacterial cells. Which microscopy technique would best allow you to distinguish and count only the living cells if they are stained with a fluorescent dye?

Accepted Answer

Fluorescence microscopy

Question 12

Which of the following is a reason why microorganisms are considered essential for the survival of other life forms on Earth?

Accepted Answer

They carry out major processes for biogeochemical cycles, such as nitrogen and carbon cycling.

Question 13

Which of the following best describes the difference between magnification and resolution in microscopy?

Accepted Answer

Magnification is the ability to make an object larger, while resolution is the ability to distinguish two adjacent objects as separate.

Question 14

Which of the following is a correct statement about the evolution of microbial cells?

Accepted Answer

Life on Earth was exclusively microbial for about 3 billion years.

Question 15

Which of the following is a function of microbial communities in their environments?

Accepted Answer

They can change the chemical and physical properties of their habitats through metabolic activities.

Question 16

Which of the following is a correct statement about the genome size and gene number in Escherichia coli compared to a human cell?

Accepted Answer

A human cell has about 1,000 times more DNA per cell and 7 times more genes than E. coli.

Question 17

Which of the following best describes the main advantage of using confocal scanning laser microscopy (CSLM) in microbiology?

Accepted Answer

It produces three-dimensional images by focusing on single layers of a specimen.

Question 18

Which of the following is a correct statement about the impact of microorganisms on food?

Accepted Answer

Microbial transformations, such as fermentation, are used to produce foods like cheese, yogurt, and beer.

Question 19

Which of the following historical figures is correctly matched with their contribution to microbiology?

Accepted Answer

Ferdinand Cohn – Founded bacterial classification and discovered endospores

Introduction to Microbiology: Foundations, Cell Structure, Evolution, and Impact

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