3.2.9

Question 1

Define mass extinction

Answer 1

It is when at least 75% of all species on Earth are wiped out at the same time.

Question 2

How many major mass extinction events have occurred in Earth’s history?

Answer 2

Five

Question 3

Name some factors that caused past mass extinctions

Answer 3

Tectonic plate movements, super-volcanic eruption, climatic changes (including drought and ice ages), and meteorite impact

Question 4

What is the current extinction rate and what is said to be causing it?

Answer 4

The current rate of extinction of species is thought to be 140,000 species per year since approximately 10,000 BC. The major causes for the sixth extinction are thought to be human hunting and the rapid rise in human population.

Question 5

How has mass extinction resulted in new directions in evolution?

Answer 5

Mass extinction events have created empty niches and allowed new species to evolve and diversify, leading to increased biodiversity over time.