Question 1

The elements that formed initial microbial life originated from

Accepted Answer

A)  oceans. 
B)  lightning. 
C)  supernovas. 
D)  the sun. 
E)  ozone. 
A)  oceans. 
B)  lightning. 
C)  supernovas. 
D)  the sun. 
E)  ozone. C

Question 2

Explain how banded iron formations could arise in the geologic record due to photoferrotrophy.

Accepted Answer

Photoferrotrophy is a form of anaerobic photosynthesis that uses reduced iron (Fe²⁺) as the electron donor. Fe²⁺ loses an electron (due to light energy) and is oxidized to Fe³⁺. Oxidized iron is insoluble and can form iron oxide (Fe₂O₃) precipitates when exposed to O₂. Layers colored red by iron oxides and iron oxyhydroxides [FeOₓ(OH)ᵧ] then form in the geologic record.

Question 3

Which of the following reactions suggests the plausibility for RNA chromosome replication in the RNA World model?

Accepted Answer

A)  Compared to DNA, synthesis and degradation of RNA require less energy. 
B)  Uracil, a pyrimidine in RNA, is the precursor of thymine, used in the synthesis of DNA. 
C)  Some ribozymes splice introns in mRNA. 
D)  Some ribozymes catalyze synthesis of complementary strands of RNA. 
E)  Peptide bond formation is catalyzed by ribosomal RNA. 
A)  Compared to DNA, synthesis and degradation of RNA require less energy. 
B)  Uracil, a pyrimidine in RNA, is the precursor of thymine, used in the synthesis of DNA. 
C)  Some ribozymes splice introns in mRNA. 
D)  Some ribozymes catalyze synthesis of complementary strands of RNA. 
E)  Peptide bond formation is catalyzed by ribosomal RNA. D

Question 4

Which of the following is a highly speculative issue about the early origin of life?

Accepted Answer

A)  Sufficient evidence exists that RNA might have been the first informational molecule. 
B)  Amino acids could have originated by Krebs cycle acids complexed to a dinucleotide. 
C)  Bacterial redox metabolism can be evidenced through 34S/32S ratios from 3.47 Gyr ago. 
D)  Ancestors of methanogens using H₂ and CO₂ to make CH4 and H₂O evolved early. 
E)  Panspermia, life forms originated elsewhere, were seeded on Earth by meteorites. 
A)  Sufficient evidence exists that RNA might have been the first informational molecule. 
B)  Amino acids could have originated by Krebs cycle acids complexed to a dinucleotide. 
C)  Bacterial redox metabolism can be evidenced through 34S/32S ratios from 3.47 Gyr ago. 
D)  Ancestors of methanogens using H₂ and CO₂ to make CH4 and H₂O evolved early. 
E)  Panspermia, life forms originated elsewhere, were seeded on Earth by meteorites.

Question 5

Why do bacterial antibiotics have a greater effect on diminishing the effects of nematode infection caused by Brugia malayi (the etiologic agent of filariasis) than current antinematode agents?

Accepted Answer

Certain strains of Wolbachia grow in the

Question 6

Rhizobial bacteroids and their plant hosts have evolved to have what type of symbiotic relationship?

Accepted Answer

A)  mutualistic 
B)  parasitic 
C)  commensal 
D)  ammensal 
E)  predatory 
A)  mutualistic 
B)  parasitic 
C)  commensal 
D)  ammensal 
E)  predatory

Question 7

Which of the following is NOT correct about endolithic microorganisms?

Accepted Answer

A)  They have been found in mines as deep as 3 kilometers. 
B)  Their discovery elicited interest in NASA scientists seeking life on Mars. 
C)  They can grow in Earth's core. 
D)  The term "endolithic" means living "within rocks." 
E)  They metabolize by oxidizing e- donors generated through decay of radioactive metals. 
A)  They have been found in mines as deep as 3 kilometers. 
B)  Their discovery elicited interest in NASA scientists seeking life on Mars. 
C)  They can grow in Earth's core. 
D)  The term "endolithic" means living "within rocks." 
E)  They metabolize by oxidizing e- donors generated through decay of radioactive metals.

Question 8

"Incompletely described," emerging organisms are on their way to be established as new species. In the meantime, they can be designated as all of the following EXCEPT a(n)

Accepted Answer

A)  unclassified organism. 
B)  uncultured organism. 
C)  environmental sample 
D)  type species. 
E)  candidate species. 
A)  unclassified organism. 
B)  uncultured organism. 
C)  environmental sample 
D)  type species. 
E)  candidate species.

Question 9

Use the figure below to describe the appearance of the Cit⁺ mutation in Escherichia coli during the Long-Term Evolution Experiment (LTEE).

Accepted Answer

After 33,000 generations in which twelve

Question 10

How do membrane compartments spontaneously arise from the properties of fatty acid glycerol esters?

Accepted Answer

Jack Szostak demonstrated that membrane-

Question 11

Mitochondria maintained the essential genes ________ from the ancestral endosymbiont from which they evolved.

Accepted Answer

A)  NADH dehydrogenase, cytochrome oxidase, and ATP synthetase 
B)  pyruvate dehydrogenase, citrate synthase, and fumarase 
C)  hexokinase, phosphoglucose isomerase, and phosphofructokinase 
D)  photosystem I and II and ATP synthetase 
E)  catalase, superoxide dismutase, and peroxidase 
A)  NADH dehydrogenase, cytochrome oxidase, and ATP synthetase 
B)  pyruvate dehydrogenase, citrate synthase, and fumarase 
C)  hexokinase, phosphoglucose isomerase, and phosphofructokinase 
D)  photosystem I and II and ATP synthetase 
E)  catalase, superoxide dismutase, and peroxidase

Question 12

Which of the following would be considered a gene product of an "informational gene"?

Accepted Answer

A)  Staphylococcus toxic shock toxin 
B)  siderophore transport protein 
C)  hexokinase enzyme for glycolysis 
D)  Escherichia coli O157:H7 attachment pili 
E)  16S ribosomal RNA 
A)  Staphylococcus toxic shock toxin 
B)  siderophore transport protein 
C)  hexokinase enzyme for glycolysis 
D)  Escherichia coli O157:H7 attachment pili 
E)  16S ribosomal RNA

Question 13

Based on small subunit rRNA phylogeny studies, the current view is that there are ________ domains of life.

Accepted Answer

A)  two 
B)  three 
C)  four 
D)  five 
E)  six 
A)  two 
B)  three 
C)  four 
D)  five 
E)  six

Question 14

What criteria must be met in order to prove that two bacterial strains belong in the same species?

Accepted Answer

Similarity of the sequences of their SSU

Question 15

Discuss what horizontal gene transfer is. How does it occur and how might it obscure phylogenetic relationships among taxa?

Accepted Answer

The acquisition of a piece of DNA from a

Question 16

Analyze the figure below. If a d ¹³C isotope analysis was performed on an unknown geological sample of sedimentary graphite and determined a negative d ¹³C % value, would it be determined that life had existed in that sample or not, and why?

Accepted Answer

Life could have existed in the sample. A

Question 17

Horizontal gene transfer can occur by all of the following EXCEPT

Accepted Answer

A)  plasmid acquisition. 
B)  transposable genetic elements. 
C)  bacteriophage infection. 
D)  transformation processes. 
E)  parent to offspring. 
A)  plasmid acquisition. 
B)  transposable genetic elements. 
C)  bacteriophage infection. 
D)  transformation processes. 
E)  parent to offspring.

Question 18

Analyses of d¹³C % has revealed biosignatures in

Accepted Answer

A)  igneous rock. 
B)  mantle rock. 
C)  carbonate rock. 
D)  sedimentary rock. 
E)  calcareous sand. 
A)  igneous rock. 
B)  mantle rock. 
C)  carbonate rock. 
D)  sedimentary rock. 
E)  calcareous sand.

Question 19

The figure below displays secondary symbiont alga Guillardia theta. Describe the process by which this relationship began.

Accepted Answer

Guillardia theta is a newly formed speci

Question 20

Evidence in the study of adaptive evolution CANNOT be obtained from

Accepted Answer

A)  comparisons of gene sequences within a genome. 
B)  comparisons of gene sequences between genomes. 
C)  the study of microorganisms growing in strongly selective environments. 
D)  sequencing a single genome several times (deep sequencing). 
E)  experimental evolution. 
A)  comparisons of gene sequences within a genome. 
B)  comparisons of gene sequences between genomes. 
C)  the study of microorganisms growing in strongly selective environments. 
D)  sequencing a single genome several times (deep sequencing). 
E)  experimental evolution.

Exam 17: Origins and Evolution

The elements that formed initial microbial life originated from

Explain how banded iron formations could arise in the geologic record due to photoferrotrophy.

Which of the following reactions suggests the plausibility for RNA chromosome replication in the RNA World model?

Which of the following is a highly speculative issue about the early origin of life?

Why do bacterial antibiotics have a greater effect on diminishing the effects of nematode infection caused by Brugia malayi (the etiologic agent of filariasis) than current antinematode agents?

Rhizobial bacteroids and their plant hosts have evolved to have what type of symbiotic relationship?

Which of the following is NOT correct about endolithic microorganisms?

"Incompletely described," emerging organisms are on their way to be established as new species. In the meantime, they can be designated as all of the following EXCEPT a(n)

Use the figure below to describe the appearance of the Cit⁺ mutation in Escherichia coli during the Long-Term Evolution Experiment (LTEE).

How do membrane compartments spontaneously arise from the properties of fatty acid glycerol esters?

Mitochondria maintained the essential genes ________ from the ancestral endosymbiont from which they evolved.

Which of the following would be considered a gene product of an "informational gene"?

Based on small subunit rRNA phylogeny studies, the current view is that there are ________ domains of life.

What criteria must be met in order to prove that two bacterial strains belong in the same species?

Discuss what horizontal gene transfer is. How does it occur and how might it obscure phylogenetic relationships among taxa?

Analyze the figure below. If a d ¹³C isotope analysis was performed on an unknown geological sample of sedimentary graphite and determined a negative d ¹³C % value, would it be determined that life had existed in that sample or not, and why?

Horizontal gene transfer can occur by all of the following EXCEPT

Analyses of d¹³C % has revealed biosignatures in

The figure below displays secondary symbiont alga Guillardia theta. Describe the process by which this relationship began.

Evidence in the study of adaptive evolution CANNOT be obtained from

Microbial Life: Origin and Discovery

Observing the Microbial Cell

Cell Structure and Function

Bacterial Culture, Growth, and Development

Environmental Influences and Control of Microbial Growth

Viruses

Genomes and Chromosomes

Transcription, Translation, and Bioinformatics

Gene Transfer, Mutations, and Genome Evolution

Molecular Regulation

Viral Molecular Biology

Biotechniques and Synthetic Biology

Energetics and Catabolism

Electron Flow in Organotrophy, Lithotrophy, and Phototrophy

Biosynthesis

Food and Industrial Microbiology

Bacterial Diversity

Archaeal Diversity

Eukaryotic Diversity

Microbial Ecology

Microbes in Global Elemental Cycles

Human Microbiota and Innate Immunity

The Adaptive Immune Response

Microbial Pathogenesis

Microbial Diseases

Antimicrobial Therapy

Clinical Microbiology and Epidemiology

Filters