Timeline and Mass Extinctions (3)

Question 1

What is speciation?

Answer 1

The formation of new and distinct species in the course of evolution.

Question 2

How does speciation occur? (in relation to natural selection)

Answer 2

-Survival of the fittest refers to natural selection, which drives evolution and speciation -Only individuals with those favorable adaptations to an environment will survive -If the species changes over time, it results in speciation (different species) and evolution

Question 3

What did Charles Darwin find?

Answer 3

Species on each island are similar but differ slightly. Island species are more closely related to species on the nearest mainland.

Question 4

Give an example of Darwin’s theory that all species on islands are similar but differ slightly.

Answer 4

Flightless birds, such as the ostrich (Africa), emu (Australia), rhea(S.America) and the extinct kiwi (N. Zealand) show great similarities even though they live on different landmasses and live on different continents

Question 5

How did flightless birds separate?

Answer 5

Birds separated geographically when Gondwanaland separated

Question 6

What did the separation of Gondwanaland lead to? (2)

Answer 6

-Climates and habitats changed due to continental drift -New species developed due to different mutations and selections in their various environments

Question 7

What is the dead zone and why is it important?

Answer 7

Rock layers without fossils – dead zone The chemical composition of the rocks contains clues about the causes of the extinction.

Question 8

Why did species become extinct? (5)

Answer 8

-Species couldn’t adapt to changing environmental conditions -They didn’t have time to adapt to the quickly changing conditions -Other species developed into new species (old species no longer existed) -New species were better competitors and existing species couldn’t survive -Species were killed by whatever caused the mass extinction

Question 9

What is an extinction?

Answer 9

When massive numbers of species all over the world die simultaneously

Question 10

How many mass extinctions have there been?

Answer 10

5

Question 11

Put the 5 mass extinctions in order.

Answer 11

Ordivician Devonian Permian-Triassic Late Triassic Cretaceous tertiary

Question 12

What were death rates for each mass extinction? Ordovician Devonian Permian-Triassic Late Triassic Cretaceous tertiary

Answer 12

Question 13

What were the causes of each extinction?

Ordivician

Devonian

Permian-Triassic

Late Triassic

Cretaceous tertiary

Answer 13

Question 14

What is the sixth extinction?

Answer 14

• Damage is done by a man causing the extinction of species very quickly
• This extinction is caused by man
• Extinction is much faster than any previous extinction (taking decades instead of millions of years!)

Question 15

What are the causes of the sixth extinction? (3)

Answer 15

• Exploitation of natural resources
• Habitat destruction
• Pollution

Question 16

What caused the mass extinction? (4)

Answer 16

• Volcanic eruptions
• Continental drift
• Ice ages
• Meteorites

Question 17

Explain how volcanic eruptions caused mass extinction. (5)

Answer 17

1. Ash and dust blocked rays of Sun
2. No photosynthesis
3. Cooling of Earth
4. Acid rain
5. Global warming

Question 18

Explain how continental drift caused mass extinctions. (3)

Answer 18

• Plates of Earth’s crust move over melted rock
• Where plates join and rub against each other, volcanoes and earthquakes occur
• Continental drift is responsible for forming mountains

Question 19

What did continental drift result in? (3)

Answer 19

1. Increased competition between species
2. Changes in abiotic conditions that led to habitat changes
3. Increased volcanic activity

Question 20

Explain how ice ages caused mass extinctions. (5)

Answer 20

Most important effect: much drier earth with much less available water

Effects:

Lower sea levels

Warm inland seas dried up or became colder

Species migrated northwards to the equator

Less water available

Question 21

What happens when a meteorite collides with Earth? (6)

Answer 21

• Dust: no photosynthesis
• Sulphuric acid: acid rain
• Earth cooled down
• Animals couldn’t control body temperature died
• Gaseous exchange processes of organisms and availability of oxygen affected
• Fires