Evolution Flashcards – AQA GCSE Combined Science: Trilogy (8464) — Biology — Foundation

Under what condition does natural selection occur?

Individuals with different heritable phenotypes differ in survival or reproductive success.

How can selection pressures such as predation, disease and competition affect phenotypes?

They can favour phenotypes that provide an advantage in the prevailing conditions.

How are favourable alleles passed on through natural selection?

Individuals with advantageous phenotypes are more likely to reproduce and pass their favourable alleles to offspring.

How can natural selection cause evolution over generations?

Favourable alleles can increase in frequency in the population’s gene pool.

What is evolution?

A change in allele frequencies in a population over time.

When did the earliest simple life forms develop?

More than three billion years ago.

How are all living species related to the earliest simple life forms?

They evolved from them through descent with inherited change over many generations.

How does the branching history of life arise?

Evolutionary lineages diverge from ancestral populations.

Why can species that share an ancestor have characteristics in common?

They inherit characteristics from their shared ancestral lineage.

What is speciation?

The formation of new species from an existing species.

How can separated populations accumulate inherited differences over generations?

They exchange few or no alleles, and differences accumulate, including through natural selection in different environments.

How may the phenotypes of separated populations change as inherited differences accumulate?

Their phenotypes may become increasingly different.

When are two populations regarded as distinct species?

When they can no longer interbreed to produce fertile offspring.