Question 1

Which of the following statements is FALSE concerning the universal tree of life?

Accepted Answer

A)   Previous versions of the universal tree of life were based largely on fossils and comparative biology, which overlooked the diversity of and relationships between most prokaryotes.
B)   The current universal tree of life is supported by multiple genes including SSU rRNA sequences.
C)   The current universal tree of life depicts three domains of life, two of which are prokaryotic.
D)   The current universal tree of life is based on molecular sequences and completely changes our view of evolutionary relationships between eukaryotic species. D

Question 2

Can gene frequencies change in the absence of selection? Why or why not?

Accepted Answer

Gene frequencies do change in the absence of selection. Genetic drift is a random process through which gene frequencies change. By chance, some members of a population will have more offspring than others, while other members may be killed or inhibited by CHANCE, not selection. An example is the random selection of very few cells from one test tube culture to another test tube. Which cells are transferred will affect which genes are passed on to offspring, but the cells transferred were random and unrelated to the fitness of the cells. Thus gene frequencies can change (drift) randomly over time even when there is no selection on that particular gene. Although genetic drift is separate from selection, it is still an important part of evolution.

Question 3

Oxygen was a driving factor in the formation of eukaryotic cells.

Accepted Answer

A) True 
 B)False  TRUE

Question 4

Which is NOT a characteristic of a ʺprimitiveʺ state of microbial evolution?

Accepted Answer

A)   hyperthermophilic
B)   aerobic metabolism
C)   small genome
D)   branching near the root of the evolutionary tree of life

Question 5

DNA-DNA hybridization is a sensitive method for revealing subtle genetic differences because it measures the degree of sequence similarity between two genomes.

Accepted Answer

A) True 
 B)False

Question 6

If you allowed 10 identical parallel Salmonella cultures to evolve for 10,000 generations under new growth conditions with very little nitrogen, the parallel cultures would

Accepted Answer

A)   evolve identical adaptations to use the nitrogen source provided in the media.
B)   not change or adapt very much over this small number of generations.
C)   each accumulate different random mutations resulting in different adaptations to use the nitrogen in the media.
D)   direct mutations to occur in nitrogen utilization and uptake genes in order to adapt rapidly to the culture conditions.

Question 7

All unicellular organisms belong to the same domain of life.

Accepted Answer

A) True 
 B)False

Question 8

The primary domains were founded based on comparative ribosomal RNA gene sequencing.

Accepted Answer

A) True 
 B)False

Question 9

Multilocus sequence typing (MLST) involves sequencing several different

Accepted Answer

A)   genomes.
B)   housekeeping genes.
C)   tRNA genes.
D)   rRNA genes.

Question 10

Both deletions and insertions occur during the evolution of microbial genomes. Insertions bring in new genes that may be useful for the cell. Deletions

Accepted Answer

A)   may increase fitness of a microorganism by eliminating unneeded genes.
B)   always result in a severe loss of fitness for the microorganism.
C)   are uncommon because they are usually lethal.
D)   always result in a severe loss of fitness but keep microbial genomes compact.

Question 11

Explain the endosymbiotic theory. What is the evolutionary value of endosymbiosis?

Accepted Answer

The answer of Explain the endosymbiotic theory. What is the...

Question 12

Eukaryotes originated after the rise in atmospheric oxygen.

Accepted Answer

A) True 
 B)False

Question 13

Microbial ________ studies the diversity of microorganisms and links their phylogeny with ________.

Accepted Answer

A)   taxonomy / genotype
B)   phylogeny / phenotype
C)   taxonomy / phenotype
D)   systematics / taxonomy

Question 14

What type of methods are used in microbial systematics? Why are multiple methods used to characterize and classify microbial species? Be sure to define the methods and describe the general strengths and weaknesses of each type.

Accepted Answer

The answer of What type of methods are used in...

Question 15

Systematic analysis now commonly includes ________ to identify, characterize, and determine relationships between new strains of bacterial species.

Accepted Answer

A)   whole genome analysis
B)   microscopy
C)   staining
D)   pigments

Question 16

A gene for a specific trait may have more than one form, allowing the trait to vary. These sequence variants of a gene are called a(n)

Accepted Answer

A)   alleles.
B)   MLST.
C)   horizontal gene transfers.
D)   ribotypes.

Question 17

The earliest photosynthetic microbes, before the cyanobacterial lineage developed, oxidized substances other than water. What was produced by these microbes instead of oxygen?

Accepted Answer

A)   nitrate
B)   elemental sulfur
C)   ferrous iron
D)   hydrogen sulfide

Question 18

What two gases were most abundant on early Earth?

Accepted Answer

A)   O₂ and CO₂
B)   N₂ and H₂
C)   CO₂ and H₂
D)   CO₂ and N₂

Question 19

The establishment of DNA as the genome of the cell may have resulted from the need to store genetic information in a more stable form than RNA.

Accepted Answer

A) True 
 B)False

Question 20

Horizontal gene transfer

Accepted Answer

A)   is so rare over evolutionary history that it is not considered when examining microbial evolution.
B)   occurs within bacterial species.
C)   complicates the construction of phylogenetic trees and the interpretation of specific traits in relation to evolution.
D)   only affects the evolution of plasmids.

Exam 13: Microbial Evolution and Systematics

Which of the following statements is FALSE concerning the universal tree of life?

Can gene frequencies change in the absence of selection? Why or why not?

Oxygen was a driving factor in the formation of eukaryotic cells.

Which is NOT a characteristic of a ʺprimitiveʺ state of microbial evolution?

DNA-DNA hybridization is a sensitive method for revealing subtle genetic differences because it measures the degree of sequence similarity between two genomes.

If you allowed 10 identical parallel Salmonella cultures to evolve for 10,000 generations under new growth conditions with very little nitrogen, the parallel cultures would

All unicellular organisms belong to the same domain of life.

The primary domains were founded based on comparative ribosomal RNA gene sequencing.

Multilocus sequence typing (MLST) involves sequencing several different

Both deletions and insertions occur during the evolution of microbial genomes. Insertions bring in new genes that may be useful for the cell. Deletions

Explain the endosymbiotic theory. What is the evolutionary value of endosymbiosis?

Eukaryotes originated after the rise in atmospheric oxygen.

Microbial studies the diversity of microorganisms and links their phylogeny with .

What type of methods are used in microbial systematics? Why are multiple methods used to characterize and classify microbial species? Be sure to define the methods and describe the general strengths and weaknesses of each type.

Systematic analysis now commonly includes ________ to identify, characterize, and determine relationships between new strains of bacterial species.

A gene for a specific trait may have more than one form, allowing the trait to vary. These sequence variants of a gene are called a(n)

The earliest photosynthetic microbes, before the cyanobacterial lineage developed, oxidized substances other than water. What was produced by these microbes instead of oxygen?

What two gases were most abundant on early Earth?

The establishment of DNA as the genome of the cell may have resulted from the need to store genetic information in a more stable form than RNA.

Horizontal gene transfer