20 Questions
What is the first step hypothesized by scientists to create the smallest living units of life?
Synthesis of small organic molecules
Which gas was not a major component of the Earth's early atmosphere?
Oxygen
What was a challenge for life to begin on early Earth due to the impact of rock and ice chunks?
Intense heat and vaporization of water
Why is understanding the composition of the early Earth's atmosphere important for determining how life began?
To understand the formation of organic molecules
When did the oldest fossils of prokaryotic cells appear according to the geological record?
2.5 – 4 billion years ago
Which era marks the appearance of the oldest fossils of eukaryotes, invertebrates, and algae?
Proterozoic
Which event led to the End Ordovician extinction around 440 million years ago?
Ice age with a loss of 86% of species
What caused the End Permian Mass extinction around 251 million years ago which resulted in the loss of 96% of species?
Massive volcanic eruption causing elevation in CO2 and acidification of oceans
Which characteristic of Archaea is unique to them and not found in bacteria or eukaryotes?
Growth at very high temperature possible
What is a distinguishing feature of Thaumarchaeota that sets them apart from other Archaea?
Ammonia-oxidizing chemolithoautotrophic behavior
Which newly proposed candidate phylum of Archaea consists of species that inhabit hot water springs?
Aigarchaeota
What is a characteristic shared by most species in the Crenarchaeota phylum?
(Acido)thermophilic anaerobes
Why was the Kingdom Monera not an accurate taxonomy for prokaryotes?
Genetic analysis revealed that traditional groups like gram-negative bacteria were not monophyletic.
How did Woese & Fox contribute to the understanding of prokaryotic classification?
They proposed the 3-domain theory based on sequencing of ribosomal RNA.
How has molecular techniques influenced the classification of prokaryotes?
Molecular techniques have led to a debate on whether the 3-domain structure is accurate.
What was Lake's hypothesis regarding the domains of life in 1984?
There should only be 2 domains: bacteria and archaea, with eukaryotes included in archaea.
Which process performed by prokaryotes is crucial for unlocking carbon, nitrogen, and other elements from dead organisms?
Decomposition
What is the primary function of cyanobacteria in relation to oxygen?
Oxygen production
Which prokaryotes are responsible for converting atmospheric N2 into nitrogenous molecules for other organisms to use?
Nitrogen fixers
In a symbiotic relationship where one species benefits and the other is unharmed, what type of relationship is this categorized as?
Commensalism
Explore the evolution of prokaryotic taxonomy and classification through genetic analysis. Learn about the traditional classification methods based on characteristics like mobility, photosynthesis, and pathogenicity, and how molecular techniques have revolutionized the understanding of prokaryotes.
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