Natural and Artificial Selection - Darwin's Deductions and Evidence for Evolution

Question 1

what four observations did Darwin make

Answer 1

• species over-reproduce
• populations tend to remain fairly constant
• there is variation within a species
• offspring often resemble their parents - characteristics are inherited

Question 2

what three deductions did Darwin make from these observation

Answer 2

• there is a struggle for survival. individuals get eaten, die of disease or competition for resources
• individuals with characteristics that best adapt them for their environment are most likely to survive and reproduce
• if these characteristics can be inherited then the organisms will pass them onto their offspring

Question 3

what did Wallace do

Answer 3

recognised for independently forming the theory of evolution through natural selection

Question 4

what does the fossil record show

Answer 4

• different species were alive in the past, these have become extinct and new species have arisen
• shows species getting more complex as time goes on
• simplest found in oldest rocks

Question 5

what are the problems with the fossil record

Answer 5

• often incomplete
• usually only hard parts decay and many organisms have no hard parts
• fossils only form under certain conditions
• fossils can be destroyed by rock movement
• suspected fake fossils

Question 6

give some more recent evidence for evolution

Answer 6

• biological molecules
• protein variation
• DNA

Question 7

how do biological molecules provide evidence for evolution

Answer 7

many biological molecules found in all organisms - suggesting all species arose from one common ancestor
closely related species have more similarities

Question 8

how does protein variation provide evidence for evolution

Answer 8

• vital proteins (e.g DNA polymerase) are found in all living organisms
• higher organisms have added subunits that improve regulation
• cytochrome c shows patterns of changes - more change=more evolutionary distance

Question 9

how does DNA provide evidence for evolution

Answer 9

sequencing the bases in DNA allows for comparison, the more differences means there is a greater evolutionary distance

Question 10

how can mitochondrial DNA provide evidence for evolution

Answer 10

• mitochondria are passed to offspring in the egg during sexual reproduction
• mutations are more common in mitochondrial DNA than genomic DNA
• variations can be used to trace human evolution