Edexcel Biology GCSE Topic 4 – Evolution and Natural
Selection
Evolution
Evolution is the slow and continuous change of a species’ inherited characteristics. We
can use fossils as evidence for the theory of evolution
Natural selection
The steps to natural selection:
1) Within a population, there is genetic variation
2) There are positive alleles that are beneficial to an organism’s survival
3) The individuals with the positive characteristics are better adapted to the
pressures that will face them in the environment
4) This means they are more likely to survive and reproduce
5) The o spring of the successful are more likely to carry the useful allele
6) The unsuccessful are less likely to reproduce
7) So the unsuccessful allele dies out over time
8) The beneficial trait becomes more common.
Antibiotic resistance
Antibiotic resistance is strong evidence for the theory of evolution. Certain organisms
within a culture of bacteria could show stronger resistance to an antibiotic. This makes
them more likely to survive. The trait is passed on, leading to a culture with high
antibiotic resistance.
Charles Darwin
Charles Darwin published his theory of evolution in 1959, after he had travelled to the
Galapagos an found variations between the islands of the archipelago.
Alfred Russel Wallace
Alfred Russel Wallace worked at the same time as Darwin, but travelled to the Malay
Archipelago and found similar results. They ended up publishing papers on evolution
together, although they didn’t always agree.
Hominid fossils
“Ardi” is the name given to a fossil of Ardipithecus ramidus. She originated from Ethiopia
and is 4.4 million years old. The structure of her feet indicates a tree climber, whilst her
Selection
Evolution
Evolution is the slow and continuous change of a species’ inherited characteristics. We
can use fossils as evidence for the theory of evolution
Natural selection
The steps to natural selection:
1) Within a population, there is genetic variation
2) There are positive alleles that are beneficial to an organism’s survival
3) The individuals with the positive characteristics are better adapted to the
pressures that will face them in the environment
4) This means they are more likely to survive and reproduce
5) The o spring of the successful are more likely to carry the useful allele
6) The unsuccessful are less likely to reproduce
7) So the unsuccessful allele dies out over time
8) The beneficial trait becomes more common.
Antibiotic resistance
Antibiotic resistance is strong evidence for the theory of evolution. Certain organisms
within a culture of bacteria could show stronger resistance to an antibiotic. This makes
them more likely to survive. The trait is passed on, leading to a culture with high
antibiotic resistance.
Charles Darwin
Charles Darwin published his theory of evolution in 1959, after he had travelled to the
Galapagos an found variations between the islands of the archipelago.
Alfred Russel Wallace
Alfred Russel Wallace worked at the same time as Darwin, but travelled to the Malay
Archipelago and found similar results. They ended up publishing papers on evolution
together, although they didn’t always agree.
Hominid fossils
“Ardi” is the name given to a fossil of Ardipithecus ramidus. She originated from Ethiopia
and is 4.4 million years old. The structure of her feet indicates a tree climber, whilst her
