NCEA Level 2 Genetic Variation

A complete set of vocabulary flashcards covering the key terms and concepts regarding genetic variation from the NCEA Level 2 curriculum.

Trait

A characteristic or feature of an organism, such as eye colour or height.

Quantitative Trait

A trait that shows a range of values and is usually controlled by many genes and the environment (e.g., height).

Qualitative Trait

A trait with distinct categories and little variation between them (e.g., blood group).

Inherited Trait

A trait passed from parents to offspring through genes.

Acquired Trait

A trait developed during an organism's lifetime due to environmental influences and not passed on genetically.

Gene

A section of DNA that codes for a specific protein or trait.

Genotype

The combination of alleles an individual has for a particular gene.

Phenotype

The observable characteristics of an organism resulting from its genotype and environment.

Dominant Allele

An allele that is expressed whenever it is present.

Recessive Allele

An allele that is only expressed when two copies are present.

Homozygous

Having two identical alleles for a gene ($AA$ or $aa$).

Heterozygous

Having two different alleles for a gene ($Aa$).

Mutation

A change in the DNA sequence that creates new genetic variation.

Gametic Mutation

A mutation that occurs in a sex cell (gamete) and can be inherited by offspring.

Somatic Mutation

A mutation that occurs in a body cell and cannot be passed to offspring.

Haploid

Having one set of chromosomes ($n$), such as sperm and egg cells.

Diploid

Having two sets of chromosomes ($2n$), one from each parent.

Crossing Over

The exchange of DNA between homologous chromosomes during meiosis.

Recombinant

A chromosome or offspring containing a new combination of alleles produced by crossing over.

Non-Recombinant

A chromosome or offspring that has the same allele combination as a parent chromosome.

Independent Assortment

The random distribution of chromosome pairs into gametes during meiosis.

Segregation

The separation of allele pairs during meiosis so each gamete receives one allele.

Incomplete Dominance

Neither allele is completely dominant, resulting in an intermediate phenotype.

Codominance

Both alleles are fully expressed in the heterozygous phenotype.

Complete Dominance

The dominant allele completely masks the recessive allele in a heterozygote.

Lethal Allele

An allele that causes death when present in a certain genotype.

Multiple Alleles

A gene with more than two allele forms in a population.

Linked Genes

Genes located on the same chromosome that tend to be inherited together.

Natural Selection

The process where individuals with advantageous traits survive and reproduce more successfully.

Evolution

A change in allele frequencies in a population over time.

Founder Effect

Reduced genetic variation when a new population is established by a small number of individuals.

Bottleneck Effect

Reduced genetic variation caused by a sudden decrease in population size.

Gene Flow

The movement of alleles between populations through migration and reproduction.

Genetic Drift

Random changes in allele frequencies, especially in small populations.