AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Evolution occurs by a process of natural selection and accounts both for…
Full specification wording
Key ideas: evolution occurs by a process of natural selection and accounts both for biodiversity and how organisms are all related to varying degrees.
Evolution is a change in the inherited characteristics of a population over many generations.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 9 of 26
- 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 many generations. It happens by natural selection. Within a population, individuals vary because of differences in their genes, often caused by mutation. Organisms compete for limited resources such as food, mates and space. Those with variations better suited to the environment are more likely to survive and reproduce, so they pass on the advantageous alleles. Over time, the useful alleles become more common in the population, and the population changes. This process can lead to new species when populations become so different that they can no longer interbreed. It also explains biodiversity, the variety of life on Earth, because different environments select for different features. All organisms share a common ancestry, so they are related to varying degrees, with closer relatives sharing more recent ancestors.
What earns the marks
- State that variation within a population arises from differences in genes, including mutations.
- Explain that organisms compete for limited resources, and those with advantageous variations are more likely to survive and reproduce.
- Describe how advantageous alleles become more common in the population over many generations.
- Explain that natural selection can lead to the formation of new species when populations become reproductively isolated.
- Link natural selection to biodiversity and to the idea that all organisms are related to varying degrees through common ancestry.
Common mistakes and how to put them right
Saying that organisms choose to change or adapt during their lifetime.
Put it right: Variation already exists, and natural selection acts on it over generations.
Thinking that individual organisms evolve.
Put it right: Populations evolve as allele frequencies change over time.
Believing that humans evolved from modern apes.
Put it right: Humans and modern apes share a common ancestor that lived in the past.
Exam tips
- Use the phrase 'survive and reproduce' to show how advantageous alleles are passed on.
- Link each step of natural selection to a change in the population, not to a single organism.
- When asked about biodiversity, refer to the variety of species and the different environments that select for different features.
Try the lesson
The start of the Key ideas: evolution occurs by a process of natural selection and accounts both for biodiversity and how organisms are all related to varying degrees. lesson, made from checked teaching notes for this specification point.
Have a go first
Which process explains why the many different species of finch on the Galapagos Islands each have a beak suited to the food available on their own island?
Listen
Evolution is a change in the inherited characteristics of a population over many generations. It happens by natural selection. Within a population, individuals vary because of differences in their genes, often caused by mutation. Organisms compete for limited resources such as food, mates and space. Those with variations better suited to the environment are more likely to survive and reproduce, so they pass on the advantageous alleles. Over time, the useful alleles become more common in the population, and the population changes. This process can lead to new species when populations become so different that they can no longer interbreed. It also explains biodiversity, the variety of life on Earth, because different environments select for different features. All organisms share a common ancestry, so they are related to varying degrees, with closer relatives sharing more recent ancestors. A strong answer earns marks for these points. State that variation within a population arises from differences in genes, including mutations. Explain that organisms compete for limited resources, and those with advantageous variations are more likely to survive and reproduce. Describe how advantageous alleles become more common in the population over many generations. Explain that natural selection can lead to the formation of new species when populations become reproductively isolated. A common slip: Saying that organisms choose to change or adapt during their lifetime. Instead, variation already exists, and natural selection acts on it over generations. Exam tip: Use the phrase 'survive and reproduce' to show how advantageous alleles are passed on.
Key words
Say what each word means before you turn the card.
Variation and mutation
Try answering aloud or in your head before turning the card.
Competition and survival
Try answering aloud or in your head before turning the card.
Natural selection over generations
Try answering aloud or in your head before turning the card.
Common ancestry and biodiversity
Try answering aloud or in your head before turning the card.
See every definition
- Variation and mutation
- Individuals within a population vary because of differences in their genes, often caused by mutation.
- Competition and survival
- Organisms compete for limited resources such as food, mates and space, and those with variations better suited to the environment are more likely to survive and reproduce.
- Natural selection over generations
- Over time, the useful alleles become more common in the population, and the population changes.
- Common ancestry and biodiversity
- All organisms share a common ancestry, so they are related to varying degrees, and different environments select for different features, explaining the variety of life on Earth.
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Key ideas: evolution occurs by a process of natural selection and accounts both for biodiversity and how organisms are all related to varying degrees.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge