Final - Origins Flashcards
(66 cards)
What is the appearance of cyanobacteria in hot springs?
Cyanobacteria appear green, with color intensity increasing as cell density increases.
This phenomenon occurs in hot springs like those in Yellowstone National Park.
Where did the first organisms flourish before the atmosphere became oxygenated?
In ocean depths or beneath the surface of Earth.
These environments provided protection from strong radiation.
What type of conditions did the first prokaryotes likely withstand?
Harsh conditions, including high temperatures.
These conditions were common due to strong volcanic activity on early Earth.
What do microbial mats represent?
The earliest forms of life on Earth.
Fossil evidence of microbial mats dates back to about 3.5 billion years ago.
What is a microbial mat?
A large biofilm, a multi-layered sheet of prokaryotes, including mostly bacteria and archaea.
Microbial mats are typically a few centimeters thick and grow on moist surfaces.
How do the various prokaryotes in a microbial mat contribute to its appearance?
They carry out different metabolic pathways, reflecting various colors.
This diversity in metabolism is due to the different types of prokaryotes present.
What substance holds prokaryotes together in a microbial mat?
A gummy-like substance secreted by the prokaryotes.
This secretion helps maintain the structure of the microbial mat.
From where did the first microbial mats likely obtain their energy?
From hydrothermal vents.
Hydrothermal vents release geothermally heated water, providing a chemical energy source.
What energy source did some prokaryotes in microbial mats evolve to use about 3 billion years ago?
Sunlight.
This was a shift from dependence on chemicals from hydrothermal vents.
What is a hydrothermal vent?
A fissure in Earth’s surface that releases geothermally heated water.
Hydrothermal vents are crucial for certain ecosystems and the origin of life.
When did life begin on Earth?
Life began on Earth with prokaryotes, existing for billions of years before plants and animals appeared.
How old is Earth?
Earth is about 4.54 billion years old.
What is the basis for estimating the age of Earth?
The estimate is based on the dating of meteorite material.
Why are surface rocks on Earth not as old as Earth itself?
Most rocks have undergone geological changes, making them younger than Earth.
What do meteorites represent in terms of Earth’s age?
Meteorites are made of original material from the solar disk and are good indicators of Earth’s formation age.
Who obtained the original estimate of Earth’s age and in what year?
Clair Patterson obtained the original estimate of 4.54 billion years in 1956.
What type of atmosphere did early Earth have?
Early Earth had an anoxic atmosphere, meaning there was no oxygen.
What type of organisms could live in an anoxic environment?
Only anaerobic organisms could live in an anoxic environment.
What are phototrophs?
Phototrophs are organisms that convert solar energy into chemical energy.
What type of phototrophic organisms appeared within one billion years of Earth’s formation?
Phototrophic organisms that required an organic source of carbon appeared.
What evolved from simple phototrophs one billion years later?
Cyanobacteria, also known as blue-green algae, evolved from simple phototrophs.
What is the significance of cyanobacteria in Earth’s history?
Cyanobacteria began the oxygenation of the atmosphere.
What did the increase in oxygen concentration allow?
The increase in oxygen concentration allowed the evolution of other life forms.
Fill in the blank: Prokaryotes were the first forms of life on Earth and existed for billions of years before _______.
plants and animals appeared.
