Changes in Biodiversity

Question 1

Conditions required for fossilisation

Answer 1

• Low oxygen
• Rapid burial of sediments
• A stable and moist environment
• Organism typically needs to contain hard/bony parts

Question 2

Steps in fossilisation

Answer 2

1. typically occurs underwater
2. organism dies and sinks to bottom of a water body
3. its body is rapidly covered by sediments
4. pressure of more sediment layers building up the weight of the water over a long period of time can turn the sediments into rock
5. hard body parts are preserved

Question 3

Fossils

Answer 3

the remains or impressions of a prehistoric plant or animal embedded in rock or preserved in petrified form

Question 4

Mineralised/petrified fossil

Answer 4

minerals from surrounding sediments leech through the bone and start to replace it. When it is dug up there is no actual bone remaining, just a stone copy.

Question 5

Mould fossil

Answer 5

bone decomposes very slowly and leaves a hole in the sedimentary rock that has formed around it. When the rock is eroded in that location, there is an impression in it.

Question 6

Cast fossil

Answer 6

rock pools over the fossil. This rock erodes slower than the sedimentary rock around it, making it visible

Question 7

Trace fossil

Answer 7

an imprinting or otherwise fragment of a fossil. Usually a print

Question 8

Transitional fossil

Answer 8

: fossils that show an intermediate species between two different types of animals

Question 9

Biosignature

Answer 9

Complex physical or chemical structures and its use of free energy and the production of biomass and wastes

Question 10

Relative Dating

Answer 10

science of determining the relative order of past events

Question 11

Principle of Superposition

Answer 11

fossils in rock strata closer to the surface are younger than rocks in deeper rock strata.

Question 12

Principle of correlation

Answer 12

if a fossil is of a similar age to others in the same layer.

Question 13

Index fossils

Answer 13

a fossil of a known age, typically very old that can be used to compare the relative age of other fossils

Question 14

Absolute Dating

Answer 14

process of determining an age on a specified chronology in archaeology and geology

Question 15

Absolute Dating Techniques

Answer 15

1. Carbon dating 14
2. Potassium argon dating
3. Electron spin resonance

Question 16

Carbon Dating 14

Answer 16

Carbon 14 is radioactive and decays over time into nitrogen 14 with a half-life of 5730 years

Question 17

Potassium Argon Dating

Answer 17

This technique determines the concentration of argon-40 in the rock near the fossil. Used to date extremely old fossils

Question 18

Biogeography

Answer 18

How organisms are distributed geographically.

Question 19

Homologous Structures

Answer 19

similar physical characteristics that indicate that species shared a (relatively) recent common ancestor (e.g. humans, cats, whales, bats have similar arms/hands)

Question 20

Analogous Structures

Answer 20

similar structures that evolved independently in species that do not share a common ancestor, yet developed the similar features due to facing similar selection pressures

Question 21

Vestigial Structures

Answer 21

no longer serves a purpose

Question 22

Comparative Embryology

Answer 22

 We can study embryos to see how we evolved through common ancestors (e.g. we can see tails, gills, etc. in vitro)

Question 23

Divergent Evolution

Answer 23

Where two species, who were originally closely related, become more dissimilar phenotypically over time.

• adaptive radiation: the rapid divergent evolution that results in lots of variation over a short period

Question 24

Convergent Evolution

Answer 24

Where two species, who were originally distantly related, become similar in their phenotypical characteristics due to encountering the same environmental conditions and selection pressures. Tends to have analogous structures because due to similar selection pressures.