6.1 and 6.2 The Origins Of Life on Earth/Exploring the Fossil Evidence

Question 1

When did life approx begin on earth?

Answer 1

3500million years ago

Question 2

How old is the earth predicted to be?

Answer 2

4500million years old

Question 3

What is the debate for where life on Earth came from?

Answer 3

Life developed due to the conditions on earth or simple life forms arrived from a different planet

Question 4

What is meant by dating rocks?

Answer 4

As fossils are found in rocks, we can date when the different organisms existed

Question 5

Why are scientists not clear about when life on Earth existed?

Answer 5

There is no repeatable or reproducible evidence

Question 6

Name 4 ways fossils can be formed.

Answer 6

• from the hard parts of animals that can’t decay, eg. Bones, teeth, shells and claws
• from organisms that haven’t decayed due to the lack of conditions for decay when they died, eg. Preserved in ice
• when the parts of the organism are replace by other materials such as minerals when they decay
• as preserved traces of organisms, eg. Footprints, burrows and rootlet traces

Question 7

Why did most organisms that does not leave a fossil?

Answer 7

The exact conditions for fossil formations were not present

Question 8

What are fossils?

Answer 8

The remains of organisms that lived many years ago which are found in rock

Question 9

Why did most early life forms not leave a fossil?

Answer 9

They had soft bodies so few traces were left behind

Question 10

Why are traces that were left behinds likely to have been destroyed?

Answer 10

Geological activity such as earthquakes would have destroyed them

Question 11

Name 3 reasons the fossil record is incomplete

Answer 11

• soft bodied organisms didn’t leave fossils
• many organisms died without the exact conditions for fossil formation
• some fossils have been destroyed over time

Question 12

What can we learn from fossils?

Answer 12

How different organisms have changed as life developed on earth

Question 13

Why can prehistoric remains stay in good shape in either glaciers, bogs or tree sap?

Answer 13

There is no oxygen reaching them there so they can’t decay

Question 14

Name 3 places where fossils can’t decay due to lack of oxygen

Answer 14

• glaciers
• bogs
• ancient tree sap

Question 15

Name 7 reasons for extinction in organisms

Answer 15

• new diseases
• new competition
• new predators
• no food
• environment dies
• habitat changes
• single catastrophic events

Question 16

Give 2 examples of habitat changes that could cause extinction of organisms

Answer 16

• rain forests being cut down

* meteors