CH11

Question 1

HALF LIFE

Answer 1

The time required for half of any quantity of radioactive material to decay into stable non-radioactive material.

Question 2

Nictitating membrane

Answer 2

A transparent fold of the skin’s third eyelid that protects the eyes of birds and reptiles and humans occurs as vestigial organ in the corner of the eye.

Question 3

Homologous structures

Answer 3

Structures with a similar structure but not necessarily a similar function

Question 4

• for fossils to be formed =

Answer 4

A quick barrel of the material needs to happen
The presence of hard body parts
An absence of decay organisms.
A long period of stability – needs to be left undisturbed

Question 5

problems with fossil records

Answer 5

Only a tiny proportion of the existing fossils have been discovered. Some are buried too deep or in inaccessible places, some have not been recognised and been destroyed by human activity. Dating the fossil may be problematic depending on the year.

Question 6

Potassium – argon dating

Answer 6

It is a technique based on the decay of radioactive potassium to form calcium and argon.
Potassium -40 is a radioactive isotope that forms calcium -40 and argon -40.
-Half-life of 1250 bill
- not all rock types are suitable for this message and can only date rocks older than 100,000 to 200,000 years.
- happens when rocks in volcanic eruptions bury bones

Question 7

artefacts

Answer 7

Objects that have been deliberately made by humans such as stone tools beads carvings caves.

Question 8

Carbon-14 dating

Answer 8

Carbon 14 is based on the decay of radioactive isotope of carbon 14 to nitrogen.
carbon 14 is formed in the upper atmosphere.
Plants absorb carbon dioxide and incorporate carbon 14 through photosynthesis. Animals and people eat plants and take in carbon 14
following death burial would and bones lose carbon 14 as it changes to nitrogen 14.
With death and organisms intake, I’ll come 14 ceases but the carbon 14 already in the tissue continues to decay at a fixed rate.
- cannot date further than 60,000 years and must contain organic compounds the amount of carbon 14 in the atmosphere varies which fluctuates the half life.

Question 9

stratigraphy

Answer 9

Is the study of layers or strata. Principle of superstition which assumes that in layers of sedimentary rock the layers on top of younger than those beneath them must be careful when applied as earths crust can be distorted and maybe turn upside dow.

The second use is the correlation of rock strata which involves matching layers of rock from different areas. Rockstar contain the same castles maybe assumed to be of the same age. Certain fossils are called index fossils.

Question 10

examples of vestigial structures

Answer 10

Wisdom teeth
Vertebrae for tail 
male have nipples
muscles at the base of hairs
human appendix