Question 1

During DNA replication in bacteria, which of the following statements is correct regarding the potential for mutations?

Accepted Answer

DNA replication via the replisome has the potential to introduce mutations.

Question 2

You isolate a bacterium from a hot spring and determine its genome size is approximately 5 Mbp. Based on typical bacterial genome organization, what is the predicted number of open reading frames (ORFs) in this genome?

Accepted Answer

4000-5000

Question 3

A researcher is studying a bacterium that grows in the dark on a medium containing hydrogen sulfide ($$\mathrm{H_2S}) as an $$electron donor and no organic carbon. Which metabolic classification best describes this organism?

Accepted Answer

Aerobic chemolithoautotroph

Question 4

Which of the following best explains why cultivation-independent methods are important for understanding microbial diversity?

Accepted Answer

It allows researchers to identify species that cannot be grown in culture.

Question 5

You are designing a filtration experiment to separate eukaryotic protists from prokaryotic cells in seawater. Which combination of filter sizes (filter 1, filter 2) would best achieve this goal?

Accepted Answer

5 $$\mum$$, 0.2 $$\mum$$

Question 6

A bacterium is discovered that thrives throughout the human colon, including both oxygen-rich and oxygen-poor regions. Which metabolic classification is most likely for this organism?

Accepted Answer

Facultatively anaerobic and chemoorganotrophic

Question 7

Which of the following statements about the early Earth environment is correct?

Accepted Answer

Ocean and atmospheric oxygen concentrations were lower than they are now.

Question 8

Which of the following is NOT evidence supporting nitrogen fixation by a bacterium?

Accepted Answer

Growth of the bacterium using nitrate ($$\mathrm{NO_3$^-}) as a $$terminal oxidant.

Question 9

Which of the following statements about the 16S rRNA gene is correct?

Accepted Answer

It is used to determine the taxonomic identity of a bacterium.

Question 10

A student changes the DNA sequence directly upstream of a start codon in an E. coli operon. After the change, the same amount of mRNA is produced, but very few proteins are made. What is the most likely function of the DNA sequence that was changed?

Accepted Answer

It likely functions as a ribosome-binding site.

Question 11

Which of the following statements about membrane transport in prokaryotes is correct?

Accepted Answer

Not all cross-membrane transport involves molecules moving down a concentration gradient.

Question 12

A chemolithoautotroph and a photoautotroph living in the same environment would be least likely to compete for which resource?

Accepted Answer

Light

Question 13

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation has a relatively low ATP yield compared to aerobic respiration.

Question 14

In Bacteria, electron transport for oxidative phosphorylation occurs primarily in which cellular structure?

Accepted Answer

Cytoplasmic membrane

Question 15

Which of the following statements about rRNA is FALSE?

Accepted Answer

rRNA is less abundant than mRNA in an actively growing microbial cell.

Question 16

In the Colman et al study (2024, Nature Communications), what did metagenomic analysis reveal about major microbial metabolisms in hot spring communities?

Accepted Answer

Metagenomes, varied among sites with different pH levels.

Question 17

Assume the mutation rate during DNA replication in Escherichia coli is $$10^{-11}$$ errors per base pair. Given a genome size of $$4.6 	imes 10^6$ base pairs and a culture containing 10^9$ cells per milliliter in 100 mL, approximately how many different base pair positions are expected to mutate during a single round of DNA replication?

Accepted Answer

Approximately 4.6 million

Question 18

Which of the following is NOT a function of the cytoplasmic membrane in prokaryotes?

Accepted Answer

It is the site of DNA replication.

Question 19

Which of the following statements about prokaryotic genomes is correct?

Accepted Answer

Most prokaryotes have a single type of chromosome, although that chromosome can occur in multiple copies in some species.

Question 20

Which of the following best describes the main difference between a plasmid and a chromosome in bacteria?

Accepted Answer

A plasmid encodes for non-essential functional genes.

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