Chapter 11

Question 1

Fossil

Answer 1

Any preserved trace left by an organism that lived long ago

Question 2

Effect of soil type on fossilisation

Answer 2

Wet acidic soils= no preservartion (unless no oxygen is present)
Alakline soil= best fossils are formed as no minerals in the bone are dissolved.

Question 3

Location of fossils

Answer 3

Human fossils are found at the edge of lakes rivers, cave systems or volcanic areas as these conditions cause immediate burial to occur

Question 4

How are fossils discovered

Answer 4

Through erosion or a slow excavation process

Question 5

What conditions allow for preservation

Answer 5

Alkaline soils, no oxygen, limestone caves ‘
Nearby lakes and river systems
Quick burial

Question 6

Dating

Answer 6

Determining the age of the fossil or material

Question 7

Absolute dating

Answer 7

The actual age of specimen in years

Question 8

Relative dating

Answer 8

A comparison of fossils to tell us whether one sample is older or younger than another

Question 9

Potassium argon dating

Answer 9

The dating technique based on the decay or radioactive potassium to form calcium and argon

Question 10

Potassium 40

Answer 10

A radioactive isotope of potassium containing 21 neutrons that decays at a constant slow rate to form calcium 40 and argon 40.

Question 11

Carbon 14 dating

Answer 11

Dating technique based on the decay of the radioactive isotope carbon 14 to nitrogen

Question 12

Carbon 12 to Carbon 14 ratio

Answer 12

1:10^12

Question 13

Half life of carbon 14

Answer 13

5730 +/- 40

Question 14

Half life of potassium 40

Answer 14

1250 billion years

Question 15

AMS and what does it involve

Answer 15

Accelerator mass spectrometry
-Involves breaking up the sample into singular atoms - so that the number of atoms in each isotope can be counted

Question 16

What does carbon 14 dating require

Answer 16

Sample must be younger than 60,000 years
Material must contain organic compounds
At least 3 grams of organic compounds (for the “normal” method withous AMS)

Question 17

Stratigraphy

Answer 17

The study of layers- strata

Question 18

Principle of superposition

Answer 18

Assumes that the layers above are younger than those beneath them
-Must be applied with caution as crust can be distorte due to tectonic activity or human/animal burials/activities

Question 19

Correlation of rock strata

Answer 19

Involves matching rock strata from different areas- as rocks that contain the same fossil may be assumed to be the same age.

Question 20

Index fossils

Answer 20

fossils that are widely distirvuted but only occured during a limited time period
-Helpful to compare rock strata and allow relative dating to e more precise

Question 21

Problems with fossil record

Answer 21

Very incomplete as conditions do not always occur or occur at irregular periods of time
4 necessary conditions
-Quick burial
-Absence of decay organisms
-Long period stability
-Presence of hard body parts

Question 22

Phylogenetic trees

Answer 22

A diagram that represents the evolutionary relationship between a number of organisms derived from a common ancestor