2.5 Mass Extinctions

Question 1

What is a mass extinction?

Answer 1

When death rates are greater than birth rates for lots of species at the same time

Question 2

How do mass extinctions promote biodiversity?

Answer 2

More food available
Lack of predators
More space or habitat for creatures to live

Question 3

How do mass extinctions cause death?

Answer 3

Mass extinctions cause death in multiple ways:

1. Suffocation
2. Physical trauma
3. Starvation
4. Poison
5. Disease

Question 4

How do flood basalt create mass extinctions?

Answer 4

A flood basalt event is a large scale volcanic eruption lasting 1000s of years
Ash from volcanoes will block out sun and cause short term global cooling
Volcanic gases build up in atmosphere causing long term global warming
Double action is devastating for life

Question 5

How do meteorite impacts cause mass extinction?

Answer 5

Huge energy released causing shockwaves and wildfires
If impact is at sea a large tsunami forms
Huge amounts of dust into atmosphere causing short term global cooling
Gases sent into atmosphere causing long term global warming

Question 6

What is the evidence of meteorite impacts?

Answer 6

Large craters
Soot and charcoal from wildfires in contemporaneous rock layers
Tektites - glass balls caused by vaporisation of rock ejected from crater
Shocked quartz - high pressure of impact alter the crystal structure
Rare elements in mud deposited around world eg iridium

Question 7

How does climate change cause mass extinction?

Answer 7

Starvation if plants cannot adapt to new climate
Knock on effect up food chain
Herbivores cannot eat - predators cannot eat
Loss of habitat increases competition for space and predation increases
Creatures live closer together so diseases spread easily
Desperation leads to eating poisonous plants or animals