AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Students should be able to describe evolution as a change in the inherited…
Full specification wording
Evolution: Students should be able to describe evolution as a change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.
Evolution is a change in the inherited characteristics of a population over time through natural selection, and it may lead to a new species.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 1 of 4
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Evolution is a change in the inherited characteristics of a population over time through natural selection, and it may lead to a new species. The mechanism starts with genetic variation from mutation and sexual reproduction. Individuals whose characteristics suit the environment survive, reproduce and pass on their alleles, so allele frequencies change over generations. A population is all the organisms of one species in a habitat, so evolution is measured in populations, not individuals. If populations become so different, or are separated so they can no longer interbreed to produce fertile offspring, a new species may form. A method is to write the chain: variation, selection pressure, survival and reproduction, inheritance, allele frequency change, possible new species.
What earns the marks
- Evolution is a change in the inherited characteristics of a population over time.
- The mechanism is natural selection acting on genetic variation within the population.
- Individuals with advantageous alleles survive, reproduce and pass those alleles to offspring.
- Allele frequencies in the population change over many generations.
- If populations become reproductively isolated and can no longer produce fertile offspring, a new species may form.
Common mistakes and how to put them right
Defining evolution as an individual organism changing during its lifetime.
Put it right by defining it as a change in a population over generations.
Saying organisms evolve because they want to survive.
Put it right by stating that variation is random and selection is non-random.
Treating evolution and natural selection as identical.
Put it right by describing natural selection as the process and evolution as the change in inherited characteristics over time.
Exam tips
- Include the words population and over time in any definition of evolution.
- Explain natural selection as a sequence of variation, selection, reproduction and inheritance.
- State that a new species forms only if populations can no longer interbreed to produce fertile offspring.
Try the lesson
The start of the Evolution: Students should be able to describe evolution as a change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species. lesson, made from checked teaching notes for this specification point.
Have a go first
How is the process of evolution defined in terms of biological populations over many generations?
Listen
Evolution is a change in the inherited characteristics of a population over time through natural selection, and it may lead to a new species. The mechanism starts with genetic variation from mutation and sexual reproduction. Individuals whose characteristics suit the environment survive, reproduce and pass on their alleles, so allele frequencies change over generations. A population is all the organisms of one species in a habitat, so evolution is measured in populations, not individuals. If populations become so different, or are separated so they can no longer interbreed to produce fertile offspring, a new species may form. A method is to write the chain: variation, selection pressure, survival and reproduction, inheritance, allele frequency change, possible new species. A strong answer earns marks for these points. Evolution is a change in the inherited characteristics of a population over time. The mechanism is natural selection acting on genetic variation within the population. Individuals with advantageous alleles survive, reproduce and pass those alleles to offspring. Allele frequencies in the population change over many generations. A common slip: Defining evolution as an individual organism changing during its lifetime. Instead, defining it as a change in a population over generations. Exam tip: Include the words population and over time in any definition of evolution.
See it
Put it in order
Put these steps in the order they happen.
- 1. Allele frequencies change over many generations
- 2. New species may form
- 3. Populations become reproductively isolated
- 4. Genetic variation from mutation and sexual reproduction
- 5. Selection pressure from the environment
- 6. Can no longer interbreed to produce fertile offspring
- 7. Individuals with advantageous alleles survive and reproduce
- 8. Advantageous alleles passed to offspring
Key words
Say what each word means before you turn the card.
Natural selection
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Evolution
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Populations and species
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Speciation and reproductive isolation
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See every definition
- Natural selection
- The process that causes evolution, acting on genetic variation within a population, in which individuals with advantageous alleles survive, reproduce and pass those alleles to offspring.
- Evolution
- A change in the inherited characteristics of a population over time through a process of natural selection, which may result in the formation of a new species.
- Populations and species
- A population is all the organisms of one species in a habitat, so evolution is measured in populations, not individuals.
- Speciation and reproductive isolation
- If populations become so different, or are separated so they can no longer interbreed to produce fertile offspring, a new species may form.
Label the diagram
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