4.6.3.1 Theory of Evolution (biology only)

Question 1

What did Charles Darwin propose and what was it backed by?

Answer 1

• Charles Darwin proposed the theory of evolution by natural selection
• as a result of observations on a round the world expedition, backed by years of experimentation and discussion and linked to developing knowledge of geology and fossils

Question 2

How and when did Charles Darwin publish his ideas?

Answer 2

• Darwin published his idea in ‘On the Origin of Species’ in 1859
• there was much controversy surrounding these revolutionary ideas

Question 3

What was Charles Darwin’s theory of evolution?

Answer 3

• individual organisms within a particular species show a wide range of variation for a characteristic
• variation exists within a species due to differences in their genes possibly as a result of mutations in DNA
• individuals with characteristics most suited to the environment are more likely to survive to breed successfully
• the genes/characteristics that have enables these individuals to survive are then passed on to the next generation (natural selection)
• over many generations the frequency of alleles/genes for this advantageous characteristic increase within the population
• individuals that are poorly adapted to their environment are less likely to survive and reproduce → this means that their genes are less likely to be passed on to the next generation

Question 4

Why was the theory of evolution by natural selection only gradually accepted?

Answer 4

• the theory challenged the idea that God made all the animals and plants that live on Earth
• there was insufficient evidence at the time the theory was published to convince many scientists
• the mechanism of inheritance and variation was not known until 50 years after the theory was published

Question 5

What was Jean-Baptise Lamarck’s theory?

Answer 5

• based mainly on the idea that changes that occur in an organism during its lifetime can be inherited
• if an individual repeated an action, the characteristic that allowed it to do this would develop further

Question 6

How was Lamarck’s theory proven wrong?

Answer 6

• know that in the vast majority of cases this type of inheritance cannot occur
• his theory was proven wrong when it was understood that changes caused by the environment were not passed on in the sex cells