10.4 Evidence For Evolution

Question 1

Charles Darwin’s theory of evolution

Answer 1

Organisms best suited to their environment are more likely to survive and reproduce
They pass their advantageous characteristics onto their offspring
Gradually a species changes over time to have a more advantageous phenotype for its environment

Question 2

What did Charles Lyell suggest in his book - principles of geology?

Answer 2

Fossils were evidence of animals that lived millions of years ago
Uniformitarianism - idea that Earth was shaped by forces, such as sedimentation in rivers, wind erosion, deposition of ash and lava

Question 3

Darwin’s famous observations on Galápagos Islands

Answer 3

Different islands had different finches
Beaks and claws were different sizes/shapes
This was linked to the food available on each island

Question 4

How would all the finch population on an island share a characteristic?

Answer 4

A bird born with a beak more suitable to the food available would survive longer than a bird whose beak was less suited
It would have more offspring, passing on characteristic beak
Over time all finches would share this beak

Question 5

Why was it useful that Darwin sent specimens of organisms back to the UK to preserve and classify?

Answer 5

Enabled scientists to see specimens first hand
Can spot characteristics and links between organisms
Eg tortoises on different islands were different subspecies

Question 6

How was the theory of evolution presented to the Linnean society of London?

Answer 6

At the same time as Darwin, Alfred Wallace was working on his own theory of evolution
Sent his ideas for peer review before publication
Similar ideas, so presented a joint presentation

Question 7

When was theory of evolution proposed to the Linnean society of London?

Answer 7

In 1858

Question 8

Darwin’s book and when it was published

Answer 8

On the origin of species

1859

Question 9

What was the name given to Darwin and Wallace’s theory of evolution?

Answer 9

Theory of evolution by natural selection

Question 10

Why was Darwin’s book controversial at the time?

Answer 10

Theory conflicted with the view that God created all animals and plants on Earth
They were created only 6000 years ago
Darwin suggested humans evolved from apes, but widely held belief was that God created man in his own image

Question 11

Evidence for evolution

Answer 11

Palaeontology
Comparative anatomy
Comparative biochemistry

Question 12

What is palaeontology?

Answer 12

The study of fossils and the fossil record

Question 13

What is comparative anatomy?

Answer 13

Study of similarities and differences between organisms’ anatomy

Question 14

What is comparative biochemistry?

Answer 14

Similarities and differences between chemical make up of organisms

Question 15

What is the fossil record?

Answer 15

Over long periods of time, sediments are deposited on Earth to form layers of rock (strata)
Different layers correspond to different geological eras - most recent is on top
Rocks form a sequence from oldest to youngest - showing gradual change over time

Question 16

Evidence provided by fossil record

Answer 16

Fossils of simplest organisms are found in the oldest rocks, more complex organisms in more recent rocks - simple life gradually evolves
Sequence in which organisms are found matches their ecological links to each other eg - plants appear before animals, as animals require plants for survival
Studying similarity in anatomy of fossil organisms can show how closely related organisms have evolved from the same ancestor
Fossils allow relationships between extinct and living organisms to be investigated

Question 17

Why is the fossil record not complete?

Answer 17

Many soft bodied organisms decompose quickly before fossilising
Conditions needed for fossil formation are not always present
Fossils could be destroyed by Earth’s movements
Fossils could be undiscovered

Question 18

What is a homologous structure?

Answer 18

Structure that appears superficially different (and could perform different functions) in different organisms, but has the same underlying structure

Question 19

What does presence of homologous structures provide evidence for?

Answer 19

Divergent evolution
Different species have evolved from a common ancestor, each with adaptive features
Occurs when closely related species diversify to adapt to new habitats due to migration or loss of habitat

Question 20

Which are the two most studied molecules in comparative biochemistry?

Answer 20

Cytochrome C - protein involved in respiration

Ribosomal RNA

Question 21

What does the hypothesis of neutral evolution state?

Answer 21

Most of the variability in the structure of a molecule doesn’t affect function
Most of the variability occurs outside the molecule’s functional regions
Changes that don’t affect function are neutral
Their accumulation is not affected by natural selection

Question 22

How to discover how closely related two species are, using comparative biochemistry

Answer 22

Molecular sequence of particular molecule is compared
Look at order of DNA bases, or order of amino acids in a protein
Number of differences are plotted against rate of neutral substitution
From this, scientists can discover when the 2 species last shared a common ancestor
Closely related species have more similar DNA and proteins