Genetic diversity is the total number of different alleles in a population.

Genetic diversity leads to variation as different combinations of alleles result in different proteins being produced, resulting in different characteristics.

Genetic diversity influences natural selection as organisms with advantageous traits are more likely to survive, reproduce, and pass on their alleles, influencing the gene pool.

The more successful an organism is at reproducing, the more likely its alleles will be passed on to the next generation, increasing the allele frequency.

1. There is variation in characteristics within a species
2. Random mutations in the gene pool may result in new alleles that produce advantageous traits
3. Organisms with advantageous alleles that make them well adapted to their environment are more likely to survive and reproduce
4. Advantageous alleles are passed onto offspring
5. Over time, these alleles become more common in the population

Directional selection is a type of natural selection where one extreme phenotype is favoured over other phenotypes, shifting the normal distribution curve in that direction.

An example is antibiotic resistance in bacteria, where the resistant bacteria survive and reproduce.

Stabilising selection favours average phenotypes.

Stabilising selection narrows the normal distribution curve.

An example is human birth weight, where infants of average weight have higher survival rates.

An allele is a variant form of a gene. Different alleles can result in different observable traits.

Drug resistance evolves when microorganisms with a mutation that confers resistance survive drug exposure, reproduce, and pass the resistant allele on to offspring. Over time, the resistant population increases.

Drug resistance can make infections harder to treat, leading to increased mortality and healthcare costs.