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The *Aquificota* phylum is primarily composed of Archaea that inhabit extreme environments.
Answer: False
Explanation: The *Aquificota* phylum consists of true bacteria, not Archaea, despite both groups often inhabiting extreme environments. They belong to the domain Bacteria.
The name *Aquificota* translates to 'water maker' and is derived from the genus *Aquifex*, reflecting its ability to produce water through hydrogen oxidation.
Answer: True
Explanation: The name *Aquificota* is indeed derived from the genus *Aquifex*, meaning 'water maker,' which accurately describes its capacity for water production via hydrogen oxidation.
*Aquificota* bacteria are typically found in temperate aquatic environments, avoiding harsh conditions.
Answer: False
Explanation: *Aquificota* bacteria are typically found in harsh aquatic environments, such as hot springs and deep-sea vents, rather than temperate conditions.
*Aquificota* bacteria are characterized as Gram-positive, spore-forming cocci.
Answer: False
Explanation: *Aquificota* bacteria are characterized as Gram-negative, non-spore-forming rods, not Gram-positive, spore-forming cocci.
Despite inhabiting similar extreme environments, *Aquificota* are classified as true bacteria, distinct from Archaea.
Answer: True
Explanation: Although *Aquificota* and Archaea can both inhabit extreme environments, *Aquificota* are classified as true bacteria within the domain Bacteria, distinguishing them from Archaea.
*Aquificota* belong to the domain Eukaryota.
Answer: False
Explanation: *Aquificota* belong to the domain Bacteria, not Eukaryota.
Being 'Gram-negative' means *Aquificota* bacteria have a thick peptidoglycan layer that retains crystal violet stain.
Answer: False
Explanation: Being 'Gram-negative' means *Aquificota* bacteria possess a cell wall structure that does *not* retain the crystal violet stain, due to their outer membrane and thinner peptidoglycan layer.
*Aquificota* are known for producing highly resistant endospores to survive harsh conditions.
Answer: False
Explanation: *Aquificota* are characterized as non-spore-forming, meaning they do not produce highly resistant endospores.
What is the fundamental nature of the *Aquificota* phylum?
Answer: A diverse group of bacteria known for inhabiting harsh environmental conditions.
Explanation: The *Aquificota* phylum represents a diverse group of true bacteria that are well-adapted to and found in harsh environmental conditions.
From which genus does the name *Aquificota* originate, and what does it signify?
Answer: *Aquifex*, meaning 'water maker'.
Explanation: The name *Aquificota* originates from the genus *Aquifex*, which translates to 'water maker,' reflecting its ability to produce water through hydrogen oxidation.
Which of the following is a typical habitat for *Aquificota* bacteria?
Answer: Harsh aquatic environments like springs and oceans.
Explanation: *Aquificota* bacteria are typically found in harsh aquatic environments, such as hot springs, geothermal pools, and deep-sea hydrothermal vents.
What are the key morphological and cellular characteristics of *Aquificota* bacteria?
Answer: Gram-negative, non-spore-forming rods.
Explanation: *Aquificota* bacteria are characterized as Gram-negative, non-spore-forming rods.
How are *Aquificota* distinguished from Archaea, despite often inhabiting similar extreme environments?
Answer: *Aquificota* are classified as true bacteria, belonging to the domain Bacteria.
Explanation: *Aquificota* are classified as true bacteria within the domain Bacteria, which fundamentally distinguishes them from Archaea, despite their shared preference for extreme environments.
What is the domain classification of *Aquificota*?
Answer: Bacteria.
Explanation: *Aquificota* are classified under the domain Bacteria.
What does 'Gram-negative' signify for *Aquificota* bacteria?
Answer: They possess a cell wall structure that does not retain the crystal violet stain.
Explanation: For *Aquificota* bacteria, being 'Gram-negative' means their cell wall structure does not retain the crystal violet stain during the Gram staining procedure.
What is the significance of *Aquificota* being 'non-spore-forming'?
Answer: They do not produce dormant, resistant structures like endospores.
Explanation: The characteristic of *Aquificota* being 'non-spore-forming' signifies that these bacteria do not produce dormant, resistant structures such as endospores.
The phylum *Aquificota* was validly published by Cavalier-Smith in 2020.
Answer: False
Explanation: The phylum *Aquificota* was validly published by Reysenbach in 2021, not by Cavalier-Smith in 2020.
The *Aquificota* phylum currently includes over 100 genera and species.
Answer: False
Explanation: The *Aquificota* phylum currently encompasses 15 genera and 42 species, not over 100 genera and species.
The three main classes comprising the *Aquificota* phylum are Aquificia, Desulfurobacteriia, and Thermosulfidibacteria.
Answer: True
Explanation: The *Aquificota* phylum is indeed composed of three distinct classes: Aquificia, Desulfurobacteriia, and Thermosulfidibacteria.
The order Aquificales includes the families Aquificaceae and Desulfurobacteriaceae.
Answer: False
Explanation: The order Aquificales includes the families Aquificaceae and Hydrogenothermaceae, not Desulfurobacteriaceae. Desulfurobacteriaceae belongs to the Desulfurobacteriales order.
The Desulfurobacteriales order is unique in containing only one family, the Desulfurobacteriaceae.
Answer: True
Explanation: The Desulfurobacteriales order is indeed characterized by containing only one family, the Desulfurobacteriaceae.
*Thermosulfidibacter takaii* is not assigned to a specific family within *Aquificota* due to its phylogenetic distinctness from both Aquificales and Desulfurobacteriales.
Answer: True
Explanation: *Thermosulfidibacter takaii* is phylogenetically distinct from both the Aquificales and Desulfurobacteriales orders, leading to its non-assignment to a specific family within *Aquificota*.
'Aquificaeota' (Oren et al. 2015) is a currently accepted name for the *Aquificota* phylum.
Answer: False
Explanation: 'Aquificaeota' (Oren et al. 2015) is listed as a historical synonym for the *Aquificota* phylum, implying it is not the currently accepted name.
The currently accepted taxonomy of *Aquificota* relies on information from the LPSN and NCBI databases.
Answer: True
Explanation: The currently accepted taxonomy for *Aquificota* is indeed based on information from the List of Prokaryotic names with Standing in Nomenclature (LPSN) and the National Center for Biotechnology Information (NCBI).
According to the LTP_10_2024 phylogenetic tree, the Aquificales order includes the Desulfurobacteriaceae family.
Answer: True
Explanation: The LTP_10_2024 phylogenetic tree indicates that the Aquificales order includes the Desulfurobacteriaceae family, among others.
The GTDB 09-RS220 classification places *Aquificota* into three main classes: Desulfurobacteriia, Aquificia, and Thermosulfidibacteria.
Answer: False
Explanation: The GTDB 09-RS220 classification places *Aquificota* into two main classes: Desulfurobacteriia and Aquificia, not three.
The kingdom classification for *Aquificota* is Pseudomonadati.
Answer: True
Explanation: According to the provided scientific classification, the kingdom for *Aquificota* is Pseudomonadati.
The Genome Taxonomy Database (GTDB) uses 16S rRNA gene sequences for its standardized bacterial and archaeal taxonomy.
Answer: False
Explanation: The Genome Taxonomy Database (GTDB) bases its standardized bacterial and archaeal taxonomy on 120 marker proteins, not primarily on 16S rRNA gene sequences.
The All-Species Living Tree Project (LTP) primarily bases its phylogenetic tree on 16S rRNA gene sequences.
Answer: True
Explanation: The All-Species Living Tree Project (LTP) primarily constructs its phylogenetic tree of prokaryotic species based on 16S rRNA gene sequences.
The Aquificales order, according to the infobox, includes the family Desulfurobacteriaceae.
Answer: False
Explanation: According to the infobox, the Aquificales order includes Aquificaceae and Hydrogenothermaceae, while Desulfurobacteriaceae is associated with the Desulfurobacteriales order.
The Desulfurobacteriales order is associated with the family Desulfurobacteriaceae in the infobox.
Answer: True
Explanation: The infobox indeed associates the Desulfurobacteriales order with the family Desulfurobacteriaceae.
The kingdom Pseudomonadati is a specific, well-detailed grouping for *Aquificota* with many shared characteristics explicitly described in the source.
Answer: False
Explanation: While *Aquificota* is classified under the kingdom Pseudomonadati, the source material does not provide extensive details or shared characteristics for this grouping.
Who is credited with the valid publication of the phylum *Aquificota* in 2021?
Answer: Reysenbach.
Explanation: Reysenbach is credited with the valid publication of the phylum *Aquificota* in 2021.
How many genera and species are currently recognized within the *Aquificota* phylum?
Answer: 15 genera and 42 species.
Explanation: The *Aquificota* phylum currently encompasses 15 genera and 42 validly published species.
Which of the following are the three main classes that comprise the *Aquificota* phylum?
Answer: Aquificia, Desulfurobacteriia, and Thermosulfidibacteria.
Explanation: The three main classes comprising the *Aquificota* phylum are Aquificia, Desulfurobacteriia, and Thermosulfidibacteria.
Which families belong to the order Aquificales within the *Aquificota* phylum?
Answer: Aquificaceae and Hydrogenothermaceae.
Explanation: The order Aquificales includes the families Aquificaceae and Hydrogenothermaceae.
What is the sole family recognized within the Desulfurobacteriales order?
Answer: Desulfurobacteriaceae.
Explanation: The Desulfurobacteriales order contains only one recognized family, the Desulfurobacteriaceae.
Why is *Thermosulfidibacter takaii* not assigned to a specific family within the *Aquificota* phylum?
Answer: It is phylogenetically distinct from both Aquificales and Desulfurobacteriales orders.
Explanation: *Thermosulfidibacter takaii* is not assigned to a specific family within *Aquificota* due to its phylogenetic distinctness from both the Aquificales and Desulfurobacteriales orders.
Which of the following is NOT a historical synonym for the *Aquificota* phylum?
Answer: 'Proteobacteria' (Garrity et al. 2005).
Explanation: 'Proteobacteria' is a distinct phylum and not a historical synonym for *Aquificota*.
Which two primary databases are used for the currently accepted taxonomy of *Aquificota*?
Answer: LPSN and NCBI.
Explanation: The currently accepted taxonomy of *Aquificota* relies on information from the LPSN (List of Prokaryotic names with Standing in Nomenclature) and NCBI (National Center for Biotechnology Information) databases.
According to the 16S rRNA based LTP_10_2024 phylogenetic tree, which family is associated with the Thermosulfidibacterales order within *Aquificota*?
Answer: Thermosulfidibacteraceae.
Explanation: The 16S rRNA based LTP_10_2024 phylogenetic tree associates the Thermosulfidibacterales order with the Thermosulfidibacteraceae family within *Aquificota*.
Based on the 120 marker proteins from GTDB 09-RS220, what are the two main classes within the *Aquificota* phylum?
Answer: Desulfurobacteriia and Aquificia.
Explanation: Based on the 120 marker proteins from GTDB 09-RS220, the two main classes within the *Aquificota* phylum are Desulfurobacteriia and Aquificia.
What kingdom is *Aquificota* classified under?
Answer: Pseudomonadati.
Explanation: The *Aquificota* phylum is classified under the kingdom Pseudomonadati.
According to the infobox, which families are included in the Aquificales order?
Answer: Aquificaceae and Hydrogenothermaceae.
Explanation: According to the infobox, the Aquificales order includes the families Aquificaceae and Hydrogenothermaceae.
CSIs are used to differentiate between the Aquificales and Desulfurobacteriales orders.
Answer: True
Explanation: Conserved Signature Indels (CSIs) are indeed utilized to differentiate between the Aquificales and Desulfurobacteriales orders, as specific CSIs are unique to each group.
*Aquificota* and Thermotogales bacteria share a unique 51-amino-acid insertion in their SecA preprotein translocase.
Answer: True
Explanation: Both *Aquificota* and Thermotogales bacteria share a unique 51-amino-acid insertion in their SecA preprotein translocase, serving as a distinct molecular signature.
In 16S rRNA gene trees, *Aquificota* species typically branch far from Thermotogota, indicating a distant evolutionary relationship.
Answer: False
Explanation: In 16S rRNA gene trees, *Aquificota* species typically branch in close proximity to Thermotogota, suggesting a close evolutionary relationship, not a distant one.
Phylogenetic studies based on Hsp70 and Hsp60 proteins strongly support a deep branching position for *Aquificota* and a close relationship with Thermotogota.
Answer: False
Explanation: Phylogenetic studies based on Hsp70 and Hsp60 proteins, along with other CSIs, do *not* support a deep branching position for *Aquificota* or a close relationship with Thermotogota; instead, they suggest a relationship with Proteobacteria.
A three-amino-acid CSI in inorganic pyrophosphatase is unique to *Aquificota* and Proteobacteria, supporting their relationship.
Answer: False
Explanation: A *two*-amino-acid CSI in inorganic pyrophosphatase is uniquely shared by *Aquificota* and Proteobacteria, not a three-amino-acid CSI.
Comparative genomic studies are crucial for identifying CSIs and understanding the evolutionary relationships within *Aquificota*.
Answer: True
Explanation: Comparative genomic studies are indeed essential for identifying conserved signature indels (CSIs) and for understanding the complex evolutionary relationships within the *Aquificota* phylum.
A two-amino-acid CSI in inorganic pyrophosphatase is shared uniquely by *Aquificota* and Proteobacteria.
Answer: True
Explanation: A unique two-amino-acid conserved signature indel (CSI) in the inorganic pyrophosphatase protein is indeed shared by species from both *Aquificota* and Proteobacteria, supporting their evolutionary relationship.
What are Conserved Signature Indels (CSIs) primarily used for in the context of *Aquificota*?
Answer: To serve as molecular markers indicating shared evolutionary history and distinguishing features.
Explanation: Conserved Signature Indels (CSIs) are primarily used as molecular markers to indicate shared evolutionary history and distinguishing features among organisms, including *Aquificota*.
How do CSIs help differentiate between the Aquificales and Desulfurobacteriales orders?
Answer: By showing specific insertions or deletions in proteins unique to each order.
Explanation: CSIs help differentiate between the Aquificales and Desulfurobacteriales orders by revealing specific insertions or deletions in proteins that are unique to each group.
What unique molecular signature is shared by *Aquificota* and Thermotogales bacteria?
Answer: A 51-amino-acid insertion in their SecA preprotein translocase.
Explanation: *Aquificota* and Thermotogales bacteria share a unique 51-amino-acid insertion in their SecA preprotein translocase.
Where do *Aquificota* species typically branch in 16S rRNA gene trees?
Answer: In close proximity to the phylum Thermotogota, near the archaeal-bacterial branch point.
Explanation: In 16S rRNA gene trees, *Aquificota* species typically branch in close proximity to the phylum Thermotogota, often near the archaeal-bacterial branch point.
What evidence contradicts a deep branching position for *Aquificota* and a close relationship with Thermotogota?
Answer: Phylogenetic studies based on other gene/protein sequences and CSIs in universal proteins.
Explanation: Phylogenetic studies utilizing other gene/protein sequences and conserved signature indels (CSIs) in universal proteins contradict a deep branching position for *Aquificota* and a close relationship with Thermotogota.
What specific molecular evidence supports a relationship between *Aquificota* and Proteobacteria?
Answer: A unique two-amino-acid CSI in the inorganic pyrophosphatase protein.
Explanation: A unique two-amino-acid CSI in the inorganic pyrophosphatase protein provides specific molecular evidence supporting a relationship between *Aquificota* and Proteobacteria.
As autotrophs, *Aquificota* bacteria are primary carbon fixers, converting inorganic carbon into organic compounds.
Answer: True
Explanation: *Aquificota* bacteria are autotrophs and play a vital ecological role as primary carbon fixers, converting inorganic carbon into organic compounds.
Members of the Desulfurobacteriales are microaerophilic and can oxidize various compounds like sulfur.
Answer: False
Explanation: Members of the Desulfurobacteriales are strict anaerobes and exclusively oxidize hydrogen, whereas Aquificales are microaerophilic and can oxidize sulfur or thiosulfate.
The SecA insertion contributes to thermostability by forming a network of water molecules that stabilize ADP/ATP binding at high temperatures.
Answer: True
Explanation: The 51-amino-acid insertion in SecA contributes to thermostability by forming a network of water molecules near the ADP/ATP binding site, which stabilizes ADP/ATP binding at high temperatures.
The high G+C content in *Aquificota* rRNAs is essential for maintaining secondary structure stability at high growth temperatures.
Answer: True
Explanation: The very high G+C content in *Aquificota* rRNAs is indeed crucial for maintaining the stability of their secondary structures, which is essential for functionality at their high growth temperatures.
*Aquificota* and Thermotogota are both classified as psychrophilic eubacteria, thriving in cold environments.
Answer: False
Explanation: *Aquificota* and Thermotogota are both classified as thermophilic eubacteria, meaning they thrive in high-temperature environments, not psychrophilic (cold-loving) environments.
A 'microaerophile' requires high concentrations of oxygen to survive.
Answer: False
Explanation: A 'microaerophile' requires oxygen, but only at lower concentrations than those present in the atmosphere, not high concentrations.
*Aquificota* are considered hyperthermophilic organisms, thriving in extremely hot environments.
Answer: True
Explanation: *Aquificota* are classified as thermophilic eubacteria, and in some contexts, are considered hyperthermophilic, thriving in extremely hot environments.
What is the ecological role of *Aquificota* bacteria in their environments?
Answer: They are primary carbon fixers, converting inorganic carbon into organic compounds.
Explanation: *Aquificota* bacteria are autotrophs and serve as primary carbon fixers, playing a crucial role in converting inorganic carbon into organic compounds.
What is a key physiological difference between members of the Desulfurobacteriales and Aquificales orders?
Answer: Desulfurobacteriales exclusively oxidize hydrogen, while Aquificales can oxidize sulfur or thiosulfate in addition to hydrogen.
Explanation: A key physiological difference is that Desulfurobacteriales are strict anaerobes that exclusively oxidize hydrogen, whereas Aquificales are microaerophilic and can oxidize various compounds, including sulfur or thiosulfate, in addition to hydrogen.
How does the 51-amino-acid insertion in SecA contribute to the thermostability of *Aquificota* bacteria?
Answer: It stabilizes ADP/ATP binding at high temperatures by forming a water molecule network.
Explanation: The 51-amino-acid insertion in SecA contributes to thermostability by forming a network of water molecules that stabilize ADP/ATP binding at high temperatures.
What is the significance of the high G+C content in the rRNAs of *Aquificota*?
Answer: It is crucial for the stability of their secondary structures at high growth temperatures.
Explanation: The high G+C content in *Aquificota* rRNAs is crucial for maintaining the stability of their secondary structures at the high growth temperatures they inhabit.
What type of eubacteria are *Aquificota* and Thermotogota classified as, based on their temperature preference?
Answer: Thermophilic.
Explanation: Both *Aquificota* and Thermotogota are classified as thermophilic eubacteria, thriving in high-temperature environments.
What is a 'microaerophile' in the context of Aquificales?
Answer: An organism that requires oxygen, but only at lower concentrations than atmospheric levels.
Explanation: In the context of Aquificales, a 'microaerophile' is an organism that requires oxygen for survival, but only at concentrations lower than those present in the atmosphere.
The 51-amino-acid insertion in SecA in *Aquificota* and Thermotogales is believed to have developed due to lateral gene transfer.
Answer: False
Explanation: Phylogenetic studies indicate that the shared 51-amino-acid insertion in SecA in *Aquificota* and Thermotogales developed independently due to selective pressure from high temperatures, not through lateral gene transfer.
CSIs in proteins like Hsp70 and AlaRS suggest a specific relationship between *Aquificota* and the phylum Proteobacteria.
Answer: True
Explanation: Evidence from CSIs in proteins such as Hsp70 and AlaRS strongly supports an evolutionary relationship between *Aquificota* and the phylum Proteobacteria, particularly Campylobacterota.
The frequent grouping of *Aquificota* with Campylobacterota is primarily due to their identical 16S rRNA gene sequences.
Answer: False
Explanation: The frequent grouping of *Aquificota* with Campylobacterota is explained by some authors as a result of frequent horizontal gene transfer between these groups, not identical 16S rRNA gene sequences.
Lateral gene transfer was the primary mechanism for the shared SecA insertion between *Aquificota* and Thermotogales.
Answer: False
Explanation: Phylogenetic studies suggest that the shared SecA insertion between *Aquificota* and Thermotogales developed independently due to selective pressure, not primarily through lateral gene transfer.
Selective pressure from cold environments led to the SecA insertion in *Aquificota*.
Answer: False
Explanation: Selective pressure from *high-temperature* environments, not cold environments, is believed to have led to the SecA insertion in *Aquificota*, as this feature enhances thermostability.
Informational genes are generally more prone to horizontal gene transfer than non-informational genes.
Answer: False
Explanation: Informational genes, involved in core cellular processes, are generally considered *less* prone to horizontal gene transfer compared to non-informational genes.
The placement of *Aquificota* near the archaeal-bacterial branch point in 16S rRNA trees suggests a recent evolutionary origin.
Answer: False
Explanation: The placement of *Aquificota* near the archaeal-bacterial branch point in 16S rRNA trees suggests they might represent one of the *earliest diverging* lineages within the Bacteria, indicating an ancient, not recent, evolutionary origin.
Cavalier-Smith suggested that *Aquificota* are closely related to Archaea.
Answer: False
Explanation: Cavalier-Smith suggested that *Aquificota* are closely related to the Proteobacteria, not Archaea.
What is the proposed reason for the shared 51-amino-acid insertion in SecA in *Aquificota* and Thermotogales?
Answer: Independent development in response to selective pressure from high temperatures.
Explanation: The shared 51-amino-acid insertion in SecA in *Aquificota* and Thermotogales is proposed to have developed independently due to selective pressure from high-temperature environments, indicating convergent evolution.
Which bacterial phylum is suggested to have a specific relationship with *Aquificota* based on CSIs in important proteins?
Answer: Proteobacteria.
Explanation: Evidence from CSIs in important proteins suggests a specific evolutionary relationship between *Aquificota* and the phylum Proteobacteria.
How do some authors explain the frequent grouping of *Aquificota* with Campylobacterota?
Answer: As a result of frequent horizontal gene transfer between these groups.
Explanation: Some authors explain the frequent grouping of *Aquificota* with Campylobacterota as a result of frequent horizontal gene transfer, likely due to shared ecological niches.
What is 'lateral gene transfer' (LGT)?
Answer: The movement of genetic material between organisms other than by parent-offspring transmission.
Explanation: Lateral gene transfer (LGT) is defined as the movement of genetic material between organisms by means other than vertical transmission from parent to offspring.
What is the significance of the 'archaeal-bacterial branch point' in *Aquificota* phylogeny?
Answer: It suggests *Aquificota* might represent one of the earliest diverging lineages within the Bacteria.
Explanation: The placement of *Aquificota* near the archaeal-bacterial branch point in 16S rRNA trees suggests they might represent one of the earliest diverging lineages within the Bacteria, indicating an ancient evolutionary origin.