Fossils

Question 1

What is a fossil

Answer 1

Any preserved trace left by an rganisms that lived in the past

Question 2

What are types of fossil

Answer 2

Burrows
Teeth
Bones
Footprints

Question 3

How are fossils formed

Answer 3

Formed when hard body parts or organisms such as bone or teeth are buried by drifting sand, deposited by rivers, volcanic ash

Question 4

Requirements for fossil formation

Answer 4

1. Quick burial
2. Presence of hard body parts
3. Absence of decay microorganisms
4. Long period of being left undisturbed

Question 5

Where are fossils often found?

Answer 5

1. Near lakes and rivers due to build up of sediment when flooding occurs
2. In caves because limestone may be deposited around dead organisms or the roof of the cave may collapse
3. Or found by chance or excavation of a site

Question 6

What are artefacts

Answer 6

Objects that have been deliberately made by humans

Question 7

Examples of artefacts

Answer 7

Stone tools
Beads
Carvings
Cave paintings

Question 8

How does the fossil record provide evidence for evolution

Answer 8

It provides evidence of which organisms lived on earth in the past and establishes links between species to determine commmon acenstry

Question 9

What are the two types of dating

Answer 9

Absolute dating

Relative Dating

Question 10

What is absolute dating?

Answer 10

Finding the actual date of a specimen

Question 11

What is relative dating?

Answer 11

Tells us if the sample is older or younger than the other

Question 12

What is potassium argon dating

Answer 12

It is dating volcanic rock next to the fossil not the fossil itself

Question 13

What is the P-A dating based on?

Answer 13

Based on the decay of radioactive potassium 40 to form calcium and argon

Question 14

What is P-A dating half-life?

Answer 14

Potassium has a half-life of 1.25-1.3B years so, over a period of 1.25B years, half the original potassium -40 would have decayed

Question 15

How can P-A age fossils?

Answer 15

The ratio of potassium 40 to argon 40 determines the age in a rock sample, the ratio of argon compared to potassium the older it is

Question 16

What is the limitations of P-A

Answer 16

1. Not all rocks are suitable because not all rocks are volcanic
2. Can only date a rock sample, not the fossil itself
3. Only date samples past 200 000 years
4. Must be suitable rock of the same age as the fossil

Question 17

What is radio carbon dating based on?

Answer 17

Based on the decay of radioactive isotope of carbon -14 to nitrogen

Question 18

What is the half-life of R-C dating?

Answer 18

Half life is 5730 years, so over a period of 5730 years there will be half the original carbon 14 amount

Question 19

How can R-C dating help to date fossils?

Answer 19

The ratio of carbon -14 to carbon 12 can help to determine the age of the fossil

Question 20

What is the limitations of R-C dating?

Answer 20

1. Required 3 grams of organic material

2. After 70 000 years the quantity of carbon -14 is too small to be used, can only date back than 60,000 years

Question 21

What is stratigraphy

Answer 21

The study of layers

Question 22

What are the principles of stratigraphy

Answer 22

1. Principle of rock strata

2. Principle of correlation of rock strata

Question 23

What is the principle fo rock strata

Answer 23

Assumes layers of the rock, the layers at the top are the younger than the below

Distortions in the earth’s crust do occur and the sequence of rock layers can be different

Question 24

What is the principle of correlation of rock strata

Answer 24

Have to match layers of rock from different areas to determine the youngest and oldest

This can be done by examining the rock and studying the fossils it contains

Particular fossils are widely distributed and were present on Earth for only a short time which can be used as index fossils