AQA GCSE Evidence of Evolution (Biology)
Evidence of Evolution
The theory of evolution by natural selection is widely accepted. It explains how living organisms change over time and how new species develop.
Today, there is strong evidence supporting this theory from:
Fossils
Antibiotic resistance in bacteria
Genetics (DNA and inheritance)
Fossil Evidence
Fossils show how organisms have changed over millions of years. Older fossils often look different from modern species, showing gradual change over time.
Fossils can also show:
Extinct species that no longer exist
Transitional forms (organisms with features of two groups).
Transitional forms represent an inbetween stage in evolution. This is where the organism has some old and new features at the same time.
This supports evolution because it shows organisms are not fixed and have changed over time.
Genetics and Inheritance
We now know that characteristics are passed on in genes. This explains how useful traits can be inherited by offspring.
Mutations create variation. If a mutation is beneficial, it can be passed on and increase survival chances.
This supports evolution because natural selection acts on inherited variation.
Antibiotic Resistance in Bacteria
Bacteria can evolve quickly because they reproduce rapidly.
Some bacteria have mutations that make them resistant to antibiotics. When antibiotics are used:
1.Non-resistant bacteria die
2.Resistant bacteria survive and reproduce
3.The population becomes mostly resistant over time
This is a real example of evolution happening today. In the image below
Stage 1: There is a mixture of antibiotic resistant and non antibiotic resistant bacteria.
Stage 2: An antibiotic is applied to the population
Stage 3: The non antibiotic resistant bacteria die
Stage 4: The antibiotic resistant bacteria have survived and reproduced. All of the population are now resistant to the antibiotic.
Scientific Evidence Today
Modern data from genetics, fossils, and observed evolution (like antibiotic resistance) all support Darwin’s theory.
This means evolution is now strongly supported by multiple lines of evidence.
Practice Questions
1.Give one way fossils provide evidence for evolution.
2.Describe how a resistant strain of bacteria can develop.
3.Why does antibiotic resistance spread quickly in bacteria?
Factors affecting the rate of photosynthesis
Measuring & calculating rates of photosynthesis
Inverse square law and photosynthesis
Economics of enhancing the conditions in greenhouses
Investigating the effect of light intensity on the rate of photosynthesis
Data analysis and nervous system
The effect of a factor on human reaction time
Controlling blood glucose concentration
Regulating water and nitrogen levels in the body.
Hormones and human reproduction
Using hormones to treat infertility
Control and coordination in plants using hormones
Investigating the effect of light or gravity on the growth of newly germinated seedlings