5.21-2

Question 1

Summarise natural selection.

Answer 1

1 - organisms in a species have variation

2 - organisms with characteristics best adapted to the environment survive and reproduce, less well adapted die. ‘Survival of the fittest’

3 - Successful genes passed on and offspring possess the genes

4 - Repeated over generations.

Question 2

What are examples of evolution (animal)?

Answer 2

Peppered moths -
Used to pale coloured, they camouflaged against trees and weren’t eaten by predators. A mutation occurred and some became dark, they were visible and eaten by birds.
- Pale moths were common but during the industrial revolution the trees turned darker due to soot, making the dark moths better adapted to not being seen and eaten, thus causing them to dominate the population of moths via natural selection.

Question 3

What are examples of evolution (bacteria)?

Answer 3

Antibiotic resistant bacteria -
Mutation occurs in bacteria, usually kills them, sometimes it’s beneficial.
E.g. antibiotic resistance
Then when a human consumes antibiotics, bacteria don’t die if they’re mutated and through survival of the fittest, bacteria survive.

Question 4

How are fossils formed?

Answer 4

Reptile dies on the ground, decomposes and skeleton left to be covered by sand or soil and clay. Skeleton over time becomes mineralised and turns to rock
It is protected beneath the ground, as the rock shifts, the fossils reappear.

Question 5

How do fossils show evidence for evolution?

Answer 5

Fossils of simpler organisms in older rocks compared to more complex organisms in newer rock show evolution.

Also closely related organisms evolving can be examined through bone structure and anatomy. Shows how the eohippus (a dog sized horse) became the modern day horse.

Question 6

What happened to some fossils?

Answer 6

Lead to gaps in fossil record

Some destroyed in volcanic eruption or soft bodied organisms decompose quickly before fossilising.

Question 7

What is a modern method of showing evidence for evolution?

Answer 7

Molecular comparison

Scientists compare DNA and proteins in species, order of bases and amino acids to find similarities and differences in organisms.

Question 8

What does extinction show?

Answer 8

Evidence for evolution
>99% of species that have lived on this planet have died due to not being able to survive the changing conditions showing evolution has happened.

Question 9

What do rapid changes in species show?

Answer 9

As bacteria replicate it shows evidence evolution in action.