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Domains of Life and Taxonomy
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Domains of Life and Taxonomy
Domains of Life and Taxonomy
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1
Question
Who initiated the most important sequence-based investigation into the domains of life?
Answer
Carl Woese.
2
Question
In what year did Carl Woese and George Fox use nucleotide sequences to determine the three domains of life?
Answer
1977.
3
Question
What are the three domains of life identified by Woese and Fox?
Answer
Archaea, Bacteria, and Eukarya.
4
Question
What is the last universal common ancestor (LUCA)?
Answer
LUCA is the most recent common ancestor of all living organisms.
5
Question
Under the three-domain system, how are organisms classified?
Answer
Organisms are classified into three domains and six kingdoms.
6
Question
What are the kingdoms within the three domains of life?
Answer
The kingdoms are Archaebacteria (ancient bacteria), Eubacteria (true bacteria), Protista, Fungi, Plantae, and Animalia.
7
Question
What did Woese argue regarding the divergence of the three domains?
Answer
He argued that these three domains each arose separately from an ancestor with poorly developed genetic machinery, often called a progenote.
8
Question
How are Eukaryotes related to Archaea and Eubacteria according to Woese?
Answer
Eukaryotes are more closely related to the Archaea than they are to the Eubacteria.
9
Question
What is the significance of bacteria in relation to human microbiota?
Answer
Some bacteria are essential to life, performing vital functions such as aiding in digestion and absorption of nutrients, preventing pathogenic microbes from colonizing, and recycling nutrients in the ecosystem.
10
Question
What is the defining characteristic of the Bacteria domain?
Answer
The Bacteria domain contains single-celled organisms that generally have a unique cell wall composition and rRNA type.
11
Question
What are the defining characteristics of Archaea?
Answer
Archaea are prokaryotic organisms that lack a membrane-bound nucleus and internal cell organelles, and they differ from bacteria in cell wall composition.
12
Question
In what extreme environments can Archaea typically be found?
Answer
Archaea can be found in hydrothermal vents, acidic springs, and under Arctic ice.
13
Question
What distinguishes the Eukarya domain from the other two domains?
Answer
Eukarya includes eukaryotes, which have a membrane-bound nucleus and distinct rRNA from bacteria and archaea.
14
Question
What are the kingdoms included in the Eukarya domain?
Answer
The kingdoms are Protista, Fungi, Plantae, and Animalia.
15
Question
What is the universal phylogenetic tree?
Answer
The universal phylogenetic tree is a representation of the evolutionary history of life based on SSU rRNA sequence analysis.
16
Question
What does the root of the universal phylogenetic tree represent?
Answer
The root represents the last universal common ancestor (LUCA) of all three domains of life.
17
Question
According to the universal phylogenetic tree, how did Archaea and Eukarya evolve?
Answer
Archaea and Eukarya evolved independently, separate from Bacteria, but shared a common ancestry.
18
Question
What is the genome fusion hypothesis?
Answer
The genome fusion hypothesis suggests that certain archaeal and bacterial genes were combined to form a single eukaryotic genome.
19
Question
What does the endosymbiotic hypothesis explain?
Answer
The endosymbiotic hypothesis explains the origin of mitochondria and chloroplasts from ancestral prokaryotes.
20
Question
What is significant about Rickettsia prowazekii in relation to mitochondria?
Answer
Rickettsia prowazekii's genome is more closely related to modern mitochondrial genomes than to any other bacterium.
21
Question
What is the hydrogen hypothesis?
Answer
The hydrogen hypothesis suggests that the endosymbiont was an anaerobic -proteobacterium that produced H2 and CO2 as end products of fermentation.
22
Question
What are the two dominant hypotheses about the origin of hydrogenosomes?
Answer
1. The hydrogenosome is a degraded form of mitochondria. 2. Hydrogenosomes and mitochondria originate from the same or different endosymbionts.
23
Question
What does the theory of punctuated equilibria explain about evolutionary processes?
Answer
Punctuated equilibria explains that evolution does not occur at a constant rate, but is characterized by periods of rapid speciation followed by long periods of stability.
24
Question
What is taxonomy?
Answer
Taxonomy is the science of biological classification, consisting of classification, nomenclature, and identification.
25
Question
What are the three interrelated parts of taxonomy?
Answer
Classification, nomenclature, and identification.
26
Question
Who developed the first natural classification system?
Answer
Carl von Linn (Carolus Linnaeus) developed the first natural classification system.
27
Question
What is polyphasic taxonomy?
Answer
Polyphasic taxonomy is an approach that includes phenotypic, phylogenetic, and genotypic features to determine the classification of organisms.
28
Question
What is phenetic classification?
Answer
Phenetic classification groups organisms based on observable characteristics such as size, shape, and staining characteristics.
29
Question
What is phylogenetic classification?
Answer
Phylogenetic classification compares organisms based on evolutionary relationships and their historical development.
30
Question
What is genotypic classification?
Answer
Genotypic classification seeks to compare the genetic similarity between organisms, often through bacterial DNA.