IB Biology Topic D3.2: Inheritance Key Definitions

An allele is a variation of a gene.

A box-and-whisker plot is a graphical representation that summarizes a dataset by showing its spread and central tendency.

The chi-squared test is a statistical method used to assess whether the occurrences of two species in a given area are due to chance or due to some form of association, possibly from ecological interactions like competition or mutualism.

Long strands of DNA, tightly coiled around histone proteins, carrying genes.

Continuous variation describes traits that exhibit a range of phenotypes without distinct categories.

Discrete variation involves traits that fall into distinct, separate categories.

A gene is a segment of DNA that codes for a specific trait, such as eye color or blood type.

The total collection of all alleles present in a population.

The intentional breeding of two different individuals that results in offspring that carry part of the genetic material of each parent.

Genotype refers to the genetic makeup of an organism, specifically the combination of alleles it inherits for a particular trait.

Haemophilia is a disorder where blood fails to clot properly due to a deficiency in a clotting factor.

Independent assortment refers to how alleles of different genes are distributed into gametes independently of one another.

A locus (plural: loci) is a gene’s exact location on a chromosome. It acts as the “address” that enables scientists to find and study genes within the human genome.

Meiosis is a type of cell division that reduces the chromosome number by half, producing four genetically distinct haploid cells. This process occurs in gamete-producing cells and is essential for sexual reproduction.

A mutation is a change in the DNA sequence, which can alter the instructions for building proteins or regulating cellular processes.

Pedigree charts are family tree diagrams that track the inheritance of traits across generations.

The phenotype of an organism refers to its observable traits or characteristics, which result from the interaction between its genetic makeup (genotype) and the environment.

Phenotypic plasticity is the ability of an organism to alter its phenotype in response to environmental changes.

A Punnett grid is a tool used to visualize the possible genotypes and phenotypes of offspring in a genetic cross.

Recombinants are individuals with new combinations of alleles and traits, differing from their parents.

Segregation is the process where the two alleles of a gene separate during gamete formation, ensuring each gamete receives only one allele.

A eukaryotic cell formed by the fusion of two gametes.