Evolution 5.1 Evidence for Evolution

Question 1

What is a species?

Answer 1

A species is a group of organisms that share common physical characteristics

Members of the same species are capable of breeding together to produce viable offspring

Question 2

What is evolution?

Answer 2

Evolution is the cumulative change in the heritable characteristics of a population

Question 3

What happens in speciation?

Answer 3

Evolution can lead one species to diverge into two separate species. One species can gradually diverge into separate species by evolution

Question 4

What do fossils tell us about evolution?

Answer 4

• Fossils demonstrate gradual change in physical characteristics of a species
• Fossils demonstrate species extinction

Fossils record the gradual change in the characteristics of a species over long periods of time

Question 5

What is a homologous structure?

Answer 5

A homologous structure is a physical characteristic shared by related species

Question 6

What does the pentadactyl limb tell us about mammals?

Answer 6

All mammals are descended from a common ancestor
The genetic code is universal.

This provides evidence that all living species share common ancestors.

Question 7

Outline the difference between artificial and natural selection.

Answer 7

Artificial selection:
Organisms are selected for a purpose (better tasting food crops, smarter sheepdogs, faster racehorses)
Artificial selection is carried out by humans

Natural selection:
Organisms are not selected for a purpose… instead the focus is on survival
Natural selection is driven by environment

Question 8

Outline a basic procedure for artificial selection

Answer 8

1. Test on which frogs jump the furthest
2. Breed the best jumping frogs
3. Wait for the offspring to grow up, then test them.
4. Repeat steps 2 and 3 for many generations

Question 9

How does artificial selection demonstrate evolution?

Answer 9

Selective breeding of domesticated animals (pets) shows this because they have evolved through human selection

Question 10

What is a cline?

Answer 10

A cline is a gradation in one or more characteristics within a species.

Question 11

Outline five types of evidence which support the

theory of evolution by natural selection

Answer 11

? fossils/paleontological: fossilized horse ancestors/other evidence
? homologous structures: pentadactyl limb/vertebrate embryos/other
? Selective breeding of domesticated animals shows that artificial selection can cause evolution
? recent observed evolution: resistance to antibiotics/melanistic (dark color) insects in polluted areas/other recent example
? geographic distribution: ring species/other evidence from geographical distribution
? biochemistry: cytochrome c/other biochemical evidence

Question 12

What explains similarities in structure when there are different function?

Answer 12

Evolution of homologous structures by adaptive radiation explains the similarity even when they have different functions.

Question 13

What is adaptive radiation?

Answer 13

When organisms come from the same origin, like from an ancestor that had a pentadactyl limb, and they become different because they perform different functions.

Question 14

What is a convergent evolution?

Answer 14

Organisms that have had different origins and have become similar because they perform the same or a similar function.

Question 15

Give evidence from patterns of variation.

Answer 15

Example: human skin colour as evidence for evolution:
• People with darker skin colour have evolved in places with high UV light –> protect them from cancer
• People with lighter skin colour have evolved in places with low UV light –> helps them to generate enough Vitamin D

Question 16

What is gradual divergence?

Answer 16

Continuous variation across the geographical range of related population matches the concept of gradual divergence.

Question 17

Does the continuous range in variation match the belief that species were created as distinct types of organisms?

Answer 17

No it does not. Continuous range in variation is not constant or unchanging.
It provides evidence for evolution and origin of species by evolution.

Question 18

How did melanistic insects evolve?

Answer 18

Dark varieties of typically light coloured insects are called melanistic. The most famous example is the peppered moth which developed the melanistic variety in polluted industrial areas for better camouflage (change in natural environment)