15 Questions
What does the term extinction mean?
The complete disappearance of a species
What is one of the biggest threats of extinction for species?
Natural disasters
When did the dinosaurs become extinct?
Following the Cretaceous extinction over 65 million years ago
What is a significant human involvement in causing extinction?
Habitat loss from human expansion and development
What is the biggest danger to most species according to the text?
Humans
What percentage of Earth's land has been adapted for human use?
75%
What percentage of Earth's freshwater resources have been used by humans?
75%
Which human activity is a major contributor to extinction in oceans?
Overfishing
What percentage of pollution comes from greenhouse gas emissions?
25%
How many species would be affected by global warming if the Earth was heated just 2 degrees Celsius?
5%
What is the natural extinction rate per year?
One species out of every one million species
Which event is considered the most recent and studied mass extinction?
Cretaceous extinction
What are the causes of notable extinct species mentioned in the text?
Hunting, climate change, and disease
What is the primary reason for scientists believing that Earth is heading towards a sixth mass extinction?
Human activities and climate change
What type of extinction occurs over a long period due to natural factors?
Background extinction
Study Notes
Understanding Extinction
- Notable extinct species include the Dodo Bird, Wooly Mammoth, Eurasian Aurochs, Sabre-tooth Cat, and Steller's Sea Cow, with causes including hunting, climate change, and disease.
- There are two main types of extinction: mass extinction, which is rare and sudden, and background extinction, a natural, long-term process.
- Mass extinction occurs when a major catastrophe leads to the death of over 50% of plant and animal life on Earth.
- Five mass extinctions have occurred on Earth, including the Ordovician-Silurian, Devonian, Permian, Triassic, and Cretaceous extinctions.
- Fossils are crucial in studying mass extinctions, providing insights into the species that became extinct and the events that led to their extinction.
- Background extinction, or the normal extinction rate, occurs over a long period due to natural factors such as climate change, population control, and predation.
- The natural extinction rate is one species out of every one million species per year, but human causes have accelerated this rate to 100-1000 times higher.
- Some scientists believe that the Earth is heading towards a sixth mass extinction, primarily due to human activities and climate change.
- Human practices like manufacturing, logging, fishing, pollution, habitat loss, and overhunting have significantly contributed to species extinction.
- Human-led extinction could be considered a third type of extinction, with impacts including sea level rise and a warming climate.
- Fossils are essential for understanding mass extinctions, providing insights into the species that became extinct and the events that led to their extinction.
- The Cretaceous extinction, the most recent and studied mass extinction, occurred 65 million years ago, and ongoing research aims to determine its exact dates and causes.
Test your knowledge about extinction with this quiz covering notable extinct species, types of extinction, mass extinctions, background extinction, human impacts, and the importance of fossils in understanding extinction events.
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