Question 1

Which of the following statements best describes a key structural difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a nucleus surrounded by a nuclear envelope, whereas prokaryotic cells lack a true nucleus.

Question 2

Which of the following is NOT a domain of life according to modern classification?

Accepted Answer

Protista

Question 3

A hospital patient develops a fever after surgery. Koch’s postulates are used to determine if a specific bacterium is the cause. Which step is NOT part of Koch’s postulates?

Accepted Answer

The pathogen must be able to survive outside the host for at least 24 hours.

Question 4

Which experiment provided the first strong evidence that DNA is the molecule of heredity?

Accepted Answer

Avery-MacLeod-McCarty experiment using purified DNA

Question 5

Which of the following best describes the function of 16S rRNA in phylogenetic studies?

Accepted Answer

It is a highly conserved component of the small ribosomal subunit, allowing comparison of evolutionary relationships among prokaryotes.

Question 6

Which of the following is a unique feature of Archaea compared to Bacteria?

Accepted Answer

Ether-linked membrane lipids

Question 7

Which scientist is credited with disproving the theory of spontaneous generation using a swan-neck flask experiment?

Accepted Answer

Louis Pasteur

Question 8

A researcher isolates a microbe from a hot spring that uses inorganic compounds as an energy source. Which scientist’s work laid the foundation for understanding this type of metabolism?

Accepted Answer

Sergei Winogradsky

Question 9

Which of the following is a correct statement about viruses?

Accepted Answer

Viruses lack cellular structure and do not possess ribosomes.

Question 10

Which of the following best explains why 16S rRNA gene sequencing is a powerful tool for microbial phylogenetics?

Accepted Answer

The 16S rRNA gene contains both highly conserved and variable regions, allowing for discrimination between distant and closely related organisms.

Question 11

Which of the following is an example of a beneficial impact of microbes on humans?

Accepted Answer

Fixing atmospheric nitrogen in the soil

Question 12

A scientist uses an enrichment culture to isolate a bacterium capable of degrading oil. Which scientist pioneered this technique?

Accepted Answer

Martinus Beijerinck

Question 13

Which of the following statements about the Avery-MacLeod-McCarty experiment is correct?

Accepted Answer

It showed that DNA, not protein or RNA, is responsible for transformation in bacteria.

Question 14

Which of the following is a phenotypic difference between Bacteria and Archaea?

Accepted Answer

Bacteria have ester-linked membrane lipids, while Archaea have ether-linked membrane lipids.

Question 15

A patient is infected with a microbe that lacks a nucleus, has a single circular chromosome, and divides by binary fission. To which group does this organism most likely belong?

Accepted Answer

Bacteria

Question 16

Which of the following best describes the impact of molecular data on our understanding of evolution?

Accepted Answer

Molecular data, such as 16S rRNA sequences, have revealed that Archaea are more closely related to Eukarya than to Bacteria.

Question 17

A researcher is studying a microbe that can use $$ \mathrm{H_2S}  as an $$energy source and $$ \mathrm{CO_2$}  as a $$carbon source. This type of metabolism is best described as:

Accepted Answer

Chemolithoautotrophy

Question 18

Which of the following is a correct application of Koch’s postulates in a real-world scenario?

Accepted Answer

Isolating a bacterium from a diseased animal, growing it in pure culture, and showing it causes the same disease in a healthy animal.

Question 19

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

Accepted Answer

Viruses lack cellular structure and do not possess the machinery for independent metabolism or reproduction.

Question 20

A scientist is comparing the genetic material of a bacterium and a eukaryote. Which of the following is a key genetic difference?

Accepted Answer

Bacteria typically have a single circular chromosome, while eukaryotes have multiple linear chromosomes.

The Microbial World: Structure, Domains, History, and Molecular Biology

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