Variation

A long strand of DNA that carries many genes. Chromosomes are found in the nucleus of cells.

A pattern of inheritance where both alleles are fully expressed at the same time in a heterozygous individual.

Example: blood type AB, where both A and B antigens are present.

A common X-linked recessive condition that affects the ability to distinguish between red and green colours.

A pattern of inheritance where one allele completely masks the effect of another. The dominant allele determines the phenotype whenever it is present.

Variation that shows a range of values with no clear categories.
Examples include height, body mass, and hand span.

A process during meiosis where homologous chromosomes exchange segments of DNA, creating new combinations of alleles.