Biodiversity Hotspots (Week 6 Lecture 9) Flashcards
How long has life existed on earth?
3.5 billion years
What percent of species that ever existed have gone extinct?
90%
______ ______ are periods in Earth’s history when abnormally large numbers of species die out simultaneously or within a limited time frame.
Mass extinctions
True or False: Extinction may be reversible.
False, irreversible
True or False: Human impacts have elevated the rate of extinction by at least a thousand to several thousand times the natural rate.
True
How many mass extinction have occurred on our planet?
5
When did the most severe mass extinction occurred.
End of the Permian period when 96% of all species destroyed
True or False: There is no benefit to a planet that undergoes a mass extinction.
False, mass extinction opens up the planet for new life forms to emerge
After what extinction did the dinosaurs appear?
Permian-Triassic extinction 250 MYA
The most studied mass extinction is the ______ extinction.
K/T
What is the great oxygenation event?
the biologically induced appearance of O2 in Earth’s atmosphere
What microbe is believed to become the first to produce oxygen by photosynthesis?
Oceanic cyanobacteria
______ ______ may have destroyed most obligate anaerobic organisms.
Free oxygen
True or False: Cyanobacteria were responsible for one of the most significantmass extinctionsin Earth’s history.
True
What was the third largest extinction in Earth’s history?
Ordovician-Silurian, 444 MYA 86% of species lost
What caused the ordovician-silurian mass extinction?
short, severe ice age that lowered sea levels, possibly triggered by the uplift of the Appalachians.
How was the planet chilled during the Ordovician-Silurian mass extinction?
Silicate rock sucked CO2 out of the atmosphere, chilling the planet
What type of species became more extinct during the Ordovician-Silurian mass extinction?
Sea creatures
True or False: The Late Devonian extinction may have been a series of extinctions over several million years, rather than a single event.
True
What was affected the most during the Late Devonian mass extinction?
Life in shallow sea areas
What happened in the Late Devonian mass extinction?
Sea bed became devoid of oxygen
What were the 4 possible causes of the Late Devonian mass extinction?
changes in sea level, asteroid impacts, climate change and new kinds of plants (most likely).
True or False: During the Permian-Triassic extinction there were at least two separate phases of extinction spread over millions of years.
True
What creatures were mostly affected during the Permian Triassic extinction?
Marine
