Evidence for Darwin's Evolution

Question 1

What are 5 pieces of evidence for Darwin’s evolution?

Answer 1

Fossils, geography, embryology, anatomy and molecular and genetic evidence

Question 2

Define fossils, relative age, index fossil and absolute age

Answer 2

Fossils - preserved remains of organisms, traces of footprints, cordites (fossilised faeces) or impressions

Relative age - expression of geological age

Index fossil - distinctive, abundant fossil with wide geographic distribution over short period of time

Absolute age - uses isotopes and half-life (can use rate of decay)

Question 3

List the 4 types of fossils.

Answer 3

Permineralisation, natural cast, amber-preserved, preserved remains

Question 4

What are permineralisation fossils?

Answer 4

Minerals carried by water are deposited around a hard structure

Question 5

What are natural cast fossils?

Answer 5

Flowing water removes all of the original tissue, leaving an impression

Question 6

What are amber-preserved fossils?

Answer 6

Organisms become trapped in tree resin that hardens after tree is buried

Question 7

What are preserved remains fossils?

Answer 7

Entire organism becomes encased in a material such as ice, ash

Question 8

Describe relative dating

Answer 8

estimates time in which organisms lived
compares placement of fossils in layers of rock
scientists infer order in which species existed

Question 9

What are issues with relative dating?

Answer 9

wind and water erode strata, some areas uplifted or tilted, people and animals dig holes which results in mixing of strata

Question 10

Describe chronometric dating

Answer 10

places events in chronological position with reference to a universal time scale (calendar)
close approximations of true age of fossil

Question 11

Describe radiometric dating

Answer 11

isotopes are unstable in their nuclei, so they decay
isotopes have known half life (no. years takes for half of isotopes to decay)
e.g. 14C has half life of 5730 yrs -> 14N is decay product, age determined by comparing ratio of 14C to 14N (wider ration = older samples)

Question 12

Explain how geography can be used as a piece of evidence.

Answer 12

Island species most closely resemble nearest mainland species, populations can shoe variation from one island to another

Question 13

Explain how embryology can be used as a piece of evidence.

Answer 13

identical larva, different adult body forms
similar embryos, diverse organisms
shows common ancestry

Question 14

What are homologous structures?

Answer 14

same structure, different function

Are evidence of common ancestor

Question 15

What are analogous structures?

Answer 15

different structure, same function

Are NOT evidence of common ancestor

Question 16

What are vestigal structures?

Answer 16

Remnants of organs or structures that had a function in early ancestor

Question 17

Explain how molecular and genetic evidence can be used as a piece of evidence.

Answer 17

2 closely-related organisms will have similar DNA, RNA, and protein (amino acid) sequences
Gives evidence of common ancestor

Question 18

Explain how anatomy can be used as a piece of evidence.

Answer 18

homologous, analogous, vestigal structures

Question 19

Define mass extinction

Answer 19

rapid and widespread extinction of large number of species due to catastrophic global event or rapid, widespread environmental change (75% species dies out)