Question 1

Which of the following is the best evidence supporting the endosymbiotic origin of mitochondria?

Accepted Answer

Mitochondria have a double membrane and their own circular DNA similar to bacteria.

Question 2

The Miller-Urey experiment demonstrated that:

Accepted Answer

Amino acids and other organic molecules can form abiotically under conditions simulating early Earth.

Question 3

Which of the following is NOT a criterion for a good molecular clock gene?

Accepted Answer

It must be horizontally transferred between species.

Question 4

Stromatolites provide evidence for early life on Earth because they are:

Accepted Answer

Bulbous masses of sedimentary layers created by bacterial communities.

Question 5

According to the RNA World hypothesis, which property of RNA supports the idea that it was the first 'information molecule'?

Accepted Answer

RNA can both store genetic information and catalyze chemical reactions.

Question 6

Which of the following best describes the Prebiotic Soup Model?

Accepted Answer

Small organic molecules formed abiotically from simple reduced chemicals, eventually leading to complex macromolecules.

Question 7

Why is the 16S rRNA gene widely used in bacterial phylogenetics?

Accepted Answer

It contains both conserved and variable regions, allowing for comparison across all life forms and discrimination between species.

Question 8

Which of the following statements about Archaea is correct?

Accepted Answer

Archaea lack peptidoglycan in their cell walls and often live in extreme environments.

Question 9

Which of the following is a key difference between the Metabolist Model and the Prebiotic Soup Model for the origin of life?

Accepted Answer

The Metabolist Model emphasizes self-sustaining abiotic chemical reactions, while the Prebiotic Soup Model focuses on the abiotic formation of small organic molecules.

Question 10

Which of the following best explains why mitochondria and chloroplasts are considered to have a prokaryotic origin?

Accepted Answer

They have circular chromosomes, 70S ribosomes, and 16S rRNA sequences similar to bacteria.

Question 11

A molecular clock is based on which of the following principles?

Accepted Answer

The accumulation of random mutations in DNA or RNA sequences over time.

Question 12

Which of the following is a real-world application of phylogenetics?

Accepted Answer

Tracing the evolutionary relationships among pathogens to track disease outbreaks.

Question 13

Which of the following statements about endosymbiosis is correct?

Accepted Answer

Endosymbionts are microbes living symbiotically inside a larger organism, often providing essential functions.

Question 14

Which of the following best describes the flow of biological information in cells?

Accepted Answer

$$ 	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein} $$

Question 15

Which of the following is a consequence of extreme reductive evolution in mitochondria and chloroplasts?

Accepted Answer

Many genes have been lost from their genomes, and the host cell provides some of their proteins.

Question 16

Which of the following is a correct statement about the three domains of life?

Accepted Answer

Archaea, Bacteria, and Eukarya are the three domains, distinguished by differences in rRNA gene sequences.

Question 17

Which of the following is a real-world example of endosymbiosis?

Accepted Answer

Rhizobia bacteria living in root nodules of legumes to fix nitrogen.

Question 18

Which of the following best explains why 16S rRNA is used as a molecular clock in bacteria?

Accepted Answer

It is present in all bacteria, has conserved and variable regions, and evolves at a constant rate.

Question 19

Which of the following statements about the endosymbiont theory is correct?

Accepted Answer

It suggests that mitochondria and chloroplasts originated from free-living bacteria that were engulfed by ancestral eukaryotic cells.

Question 20

A scientist is comparing the 16S rRNA gene sequences of several bacterial species. She finds that two species have only a 2% difference in their sequences. What does this suggest about their evolutionary relationship?

Accepted Answer

They are closely related and likely diverged from a common ancestor relatively recently.

Microbial Evolution: Origins, Phylogenetics, and Endosymbiosis

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