Deck 16: Microbial Evolution and Systematics

Question 1

Which chemotaxonomic tool would scientists use if they wanted to determine if an outbreak of food poisoning was caused by a particular strain of a pathogen?

A) FISH
B) MLST
C) FAME
D) DNA:DNA hybridization

Answer 1

B

Question 2

If a population of cells occupies a particular niche in a habitat and shares a particular resource, it is called a(n)

A) strain.
B) ecotype.
C) genus.
D) species.

Answer 2

B

Question 3

It is believed that phototrophy arose approximately 3.3 billion years ago, and only in

A) Eukarya.
B) Bacteria.
C) LUCA.
D) Archaea.

Answer 3

B

Question 4

The oxic atmosphere created conditions that led to the evolution of various new metabolic pathways, such as

A) sulfate reduction.
B) iron oxidation.
C) nitrification.
D) all of the above.

Question 5

A monophyletic group is a group that

A) possesses one taxonomic trait that is the same.
B) shares one phylogenetic marker.
C) has the same fitness level.
D) descended from one ancestor.

Question 6

Ribotyping

A) exploits unique DNA restriction patterns.
B) bypasses sequencing and sequence alignments.
C) allows discrimination between species and different strains of a species.
D) does all of the above.

Question 7

What was a major waste product of photosynthesis before the cyanobacterial lineage developed on Earth?

A) hydrogen sulfide
B) elemental sulfur
C) carbon monoxide
D) ferrous iron

Question 8

The organization of bacteria into progressively more inclusive groups based on either phenotype similarity or evolutionary relationship is known as

A) phylogeny.
B) systematics.
C) classification.
D) taxonomy.

Question 9

LUCA is

A) the last universal common ancestor.
B) actually somewhat of a misnomer because it is now believed that each of the domains arose independently.
C) the individual ancestor of each of the three domains.
D) all of the above.

Question 10

Which of the following is NOT an assumption used in the molecular clock approach?

A) Nucleotide changes are random.
B) Nucleotide changes accumulate in a sequence in proportion to time.
C) Nucleotide changes do not interfere with gene function.
D) Nucleotide changes are generally not transferred to progeny.

Question 11

Microorganisms likely did not inhabit Earth's surface until

A) aquatic life brought them onto land.
B) the ozone layer was made.
C) phototrophy evolved.
D) chemoorganotrophy developed.

Question 12

Which is NOT a characteristic of a "primitive" state of microbial evolution?

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

Question 13

Horizontal gene transfer is the transfer of genetic material

A) with the help of plasmids.
B) from any closely related organism to another.
C) from one cell to another.
D) by conjugation.

Question 14

Evolution is driven by

A) selection pressure.
B) the creation of novel metabolic pathways.
C) mutation.
D) both A and C.

Question 15

Polyphasic taxonomy uses methods that include

A) phylogenetic.
B) genotypic.
C) phenotypic.
D) all of the above.

Question 16

The earliest RNA probably functioned in

A) catalysis.
B) self- replication.
C) both catalysis and self- replication.
D) neither catalysis nor self- replication.

Question 17

Molecular sequencing suggests that mitochondria arose from a group of prokaryotic organisms within the

A) cyanobacteria.
B) Proteobacteria.
C) Crenarchaeota.
D) iron- oxidizing bacteria.

Question 18

Using present terminology, how many bacterial phyla have been discovered thus far?

A) 8, but the actual number may be as high as 25
B) 4, but the actual number may be as high as 10
C) 40, but the actual number may be higher
D) at least 80

Question 19

Compared with today, the temperature on Earth during its first half- billion years was probably

A) considerably colder.
B) about the same as today.
C) considerably warmer.
D) about the same as today on average, but the diurnal fluctuations were much greater.

Question 20

What two gases were most abundant on early Earth?

A) CO2 and N2
B) CO2 and H2
C) CH4 and H2
D) CH4 and CO2

Question 21

Because DNA:DNA hybridization reveals subtle differences in genes, it is useful for differentiating

A) very similar organisms.
B) organisms from different families.
C) organisms from different domains.
D) organisms from different orders.

Question 22

Two eukaryotic organelles that are hypothesized to be the result of endosymbiotic uptake are the and the .

Question 23

Which statement most closely expresses our present understanding?

A) The chloroplast and the cyanobacteria are not closely (or specifically) related.
B) The chloroplast arose from within the cyanobacterial phylum.
C) The chloroplast is a descendent of the cyanobacteria.
D) The cyanobacteria are descendents of the chloroplast.

Question 24

A sequence variant of a gene is called a(n)

A) allele.
B) nucleotide polymorphism.
C) ribotype.
D) mutation.

Question 25

Which molecular technique requires the complementary strand of a nucleotide sequence of interest as a probe to identify its presence?

A) FISH
B) AFLP
C) MLST
D) FAME

Question 26

The most widely used molecule in sequence- based evolutionary analyses are genes.

A) SSU rRNA
B) ATPase
C) 18S rRNA
D) electron transport

Question 27

Fluorescent phylogenetic probes are used extensively in

A) microbial ecology.
B) rapid identification of specific species.
C) clinical diagnostics.
D) all of the above.

Question 28

The substance that has been shown to catalyze various chemical reactions and that helped form the structured mounds surrounding hydrothermal springs on the ocean floor on early Earth is known as _.

Question 29

Traits currently considered most important for grouping strains together as a species include and .

Question 30

The study of the diversity of organisms and their relationships is known as , which links together _ and , in which organisms are characterized, named, and placed into groups according to their natural relationships.

Question 31

A web- based algorithm used for aligning and identifying homologous sequences is called
.

Question 32

The earliest stromatolites were probably

A) anoxygenic phototrophs.
B) oxygenic phototrophs.
C) anoxygenic lithotrophs.
D) oxygenic lithotrophs.

Question 33

In the binomial system of nomenclature, each organism is given a(n) name and a(n) epithet.

Question 34

A highly specific and rapid molecular technique called can serve as a clinical diagnostic tool to identify DNA fingerprints of infectious agents rather than performing DNA sequencing.

Question 35

The early energy reactions yielded hydrogen, which is a powerful and could have been used to form a(n) .

Question 36

The evolutionary history of a group of organisms is called its and it is inferred indirectly from .

Question 37

The rise in atmospheric oxygen, caused by the photosynthetic production of oxygen by the
, allowed for the origin of eukaryotes.

Question 38

Chemical reactions involving have been proposed as energy- yielding reactions for primitive organisms.

A) iron, sulfur, and oxygen
B) iron, oxygen, and hydrogen
C) sulfur, oxygen, and hydrogen
D) iron, sulfur, and hydrogen

Question 39

The eukaryotic functional equivalent of the prokaryotic 16S rRNA is the

A) 18S rRNA.
B) 5S rRNA.
C) 16S rRNA.
D) 23S rRNA.

Question 40

Although the microsporidia and the diplomonads are eukaryotic, they lack

A) a true nucleus.
B) identifiable ribosomes.
C) mitochondria.
D) all of the above.

Question 41

As oxygen appeared in the atmosphere, some of it accumulated in the form of , which formed a protective barrier that prevents from reaching Earth.

Question 42

In doing comparative SSU rRNA sequencing, it is essential that pure (axenic) cultures be used.

Question 43

One widely used cladistic method of examining evolutionary relationships is , which is based on the assumption that evolution is most likely to have proceeded by the path requiring fewest changes.

Question 44

The domains arose as barriers between evolved organisms.

Question 45

Two organisms containing identical GC ratios are not necessarily related.

Question 46

Oxygen did not accumulate in the early atmosphere until it reacted with reduced materials, especially , in the oceans. These substances then reacted spontaneously with oxygen to produce .

Question 47

MLST involves sequencing several different .

Question 48

Most bacterial phyla lack strong phenotypic cohesiveness.

Question 49

T- RFLP is a molecular technique often applied for phylogenetic analyses of microbial communities.

Question 50

formed the semipermeable membrane- like surfaces for the earliest life forms.

Question 51

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

Question 52

In taxonomy, family is a more general term than order.

Question 53

If two organisms' GC ratio differs by more than 5%, the two organisms likely .

Question 54

The earliest nucleic acid was probably a simple DNA molecule.

Question 55

Fossilized microbial mats consisting of layers of filamentous prokaryotes and trapped sediment are known as .

Question 56

Precambrian iron exists today primarily as in rocks.

Question 57

The 16S rRNA sequence is an approximately 1,500 bp linear strand of single stranded RNA.

Question 58

One phenotypic trait used for species identification and description is the analysis of the types and proportions of the fatty acids present in the cytoplasmic and outer membranes. The methodology employed is often nicknamed FAME.

Question 59

RDP- II is the standard abbreviation of _ .

Question 60

DNA:DNA hybridization is a sensitive method for revealing subtle genetic differences because it measures the degree of sequence similarity in two DNAs.

Question 61

None of the organisms living today are primitive.

Question 62

Why is Carl Woese an important figure in microbial classification and taxonomy?

Question 63

Explain why life is now believed to have originated at hydrothermal springs on the ocean floor rather than on the surface of Earth.

Question 64

Why is the biological species concept useful for Eukarya but not meaningful for Archaea and Bacteria?

Question 65

Explain why in both taxonomy and phylogeny the reliance on the sequence of a single gene can have pitfalls.

Question 66

At present there are four phyla in the domain Archaea.

Question 67

Lateral gene transfer is one plausible explanation as to why organisms in Archaea, Bacteria, and
Eukarya still share so many genes among such distinct domains.

Question 68

The hyperthermophilic members of the Crenarchaeota branch very close to the root of the universal tree.

Question 69

When exposed to UV light, oxygen gas produces ozone gas.

Question 70

The atmosphere of primitive Earth is usually classified as an oxidizing atmosphere.

Question 71

Explain why it is believed that the eukaryotic cell is a chimera.

Question 72

Eukaryotes originated after the rise in atmospheric oxygen.

Question 73

Construct a chart to demonstrate the characteristics of the primary domains. Which characteristics can be found in each domain? Explain any overlapping characteristics.

Question 74

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

Question 75

Hybridization values of 50% or greater are recommended for considering two isolates to be of the same species.

Question 76

Explain how gene duplication can lead to new functions in haploids.

Question 77

Describe the hydrogen hypothesis and why it is favored over other hypotheses.

Question 78

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.

Question 79

Approximately 4 billion years ago Archaea and Bacteria diverged as being distinct from each other.

Question 80

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