Organisms that are better adapted to their environment are more likely to survive, reproduce and pass on their genes to their offspring.

A feature that organisms have that helps them live in a particular place and survive.

A genetic variant is a region of DNA in which the sequence of nucleotide bases has been changed.

Natural selection at the genetic level

Combined science

Variation and genetic mutations

Mutations and evolution in bacteria

Pupils will learn about eukaryotic and prokaryotic cells, and that subcellular evidence, including from analysis of genomes, has led to the classification and sometimes reclassification of organisms into taxonomic groups from species to domains.

Pupils learned that the fossil record provides evidence of evolution from common ancestors through transitional species to modern species, and that the theory of evolution by natural selection can be used to explain phenotypic changes in populations of species over generations.

This unit covers genetic variation, comparing asexual and sexual reproduction. It explores mutations' impact on phenotypes, evolution through natural selection, and how scientific theories develop, explaining how advantageous traits lead to adaptation.

Variation and natural selection at the genetic level

deliberately to help organisms to evolve.

Izzy: Genetic variants can be helpful, harmful or neither.

Jacob: All genetic variants must be helpful, otherwise they wouldn’t happen.

Sofia: All genetic variants are harmful because they’re caused by mutations.

Laura: A genetic variant must be either harmful or helpful, it can’t be neither.

Mutations create genetic variants. Who has the correct idea about genetic variants?

Match the start of each sentence to its correct ending.

 do not change frequency over generations.

Because of natural selection, genetic variants that code for advantageous traits …

The nucleotide base sequence in DNA is changed.

The genetic variant is used as instructions for making a protein.

Because of the mutation, a different sequence of amino acids is joined together.

This may change the shape of the protein.

This may change the activity of the protein.

Put the statements in the correct order to explain how a mutation can affect an organism’s phenotype.

Individuals with the genetic variant were better adapted to their environment.

Individuals with the genetic variant were more likely to survive and reproduce.

Individuals with the genetic variant were more likely to pass it onto offspring.

Put the statements in the correct order to explain why the genetic variant that codes for black colouration in the peppered moth became more common when tree bark darkened.

only change due to selective breeding by humans.

Fossils show that the common characteristics of a species …

Lucas: Most features are caused only by our genes.

Jun: All features are caused by the environment.

Aisha: Most features are influenced by both our genes and the environment.

Who is correct about the features of organisms?

If a trait can be passed to an organism’s offspring, it is described as ...

A trait that helps an organism to survive in a particular place.

The struggle for resources that organisms need.

Individuals with advantageous traits are more likely to pass them on.

The process of making a new generation of offspring.

Match each word to its correct definition.

A mutation in an organism’s DNA creates a genetic ...

always changes the organism’s phenotype.

never changes the organism’s phenotype.

sometimes changes the organism’s phenotype.

If a mutation changes the sequence of nucleotide bases in an organism’s DNA, this …

Natural selection at the genetic level

Lesson outcome