2.5 Origins And Development Of Life On Earth

Question 1

Where did life begin?

Answer 1

Around hydrothermal vents close to mid ocean ridges in ancient oceans

Question 2

How did life begin?

Answer 2

1. Sea water percolates into crust along faults and fractures
2. Water is heated in magma chambers and dissolves hydrogen sulphide
3. Water rises and dissolves minerals out of rocks
4. Fluids reach sea floor and precipitate to form hydrothermal fluids/ black smokers
5. Bacteria around vent feed on hydrogen sulphide by chemosynthesis

Question 3

How did life diversify?

Answer 3

When continents are spread out there is more shallow sea
So more space to live and animals can diversify
When all continents are together there is less shallow sea so more competition and less diversity

Question 4

Why has life diversified?

Answer 4

Evolution over 3500 million years ago from single cell organisms to complex multicellular life because of
Climate change
Mass extinctions
Evolution of predators

Question 5

What are the problems with the fossil records?

Answer 5

Have to die in right place to be preserved, low energy, no oxygen, rapid burial or high sedimentation rate
Need to be found by someone who cares
Bias towards marine creatures 
Bias towards creatures with hard parts
Record is incomplete as many fossils have been destroyed by deformation - faults and folds
Melting 
Metamorphism 
Weathering and erosion

Question 6

When did fish first evolve?

Answer 6

Ordovician period

Question 7

What is the oldest period when all the fossil vertebrates are present?

Answer 7

Cretaceous period

Question 8

What is the order of vertebrate evolution?

Answer 8

Oldest -> youngest

Fish, amphibians, reptiles, mammals, birds