Unit 5: Hereditary Genetics

Meiosis is a type of cell division that reduces the chromosome number by ______, creating ______ cells.

half, haploid

The process in which homologous chromosomes exchange genetic material during prophase I is called ______.

crossing over

A cell with two sets of chromosomes is called ______, while a cell with one set of chromosomes is called ______.

diploid, haploid

The random alignment of homologous chromosomes during metaphase I is called ______.

independent assortment

The fusion of two gametes results in a ______, which is a ______ cell.

zygote, diploid

The law of ______ states that alleles for a trait separate during gamete formation.

segregation

The law of ______ states that genes for different traits assort independently during gamete formation.

independent assortment

An organism with two identical alleles for a trait is called ______, while one with two different alleles is called ______.

homozygous, heterozygous

A ______ allele is expressed even if only one copy is present, whereas a ______ allele is only expressed when two copies are present.

dominant, recessive

A genetic cross between two heterozygous individuals for one trait (Aa × Aa) results in a phenotypic ratio of ______.

3:1

In ______ dominance, the heterozygous phenotype is a blend of the two alleles.

incomplete

In ______, both alleles are fully expressed in the heterozygote.

codominance

A single gene affecting multiple traits is known as ______.

pleiotropy

A trait controlled by multiple genes is called a ______ trait.

polygenic

The presence of one gene affecting the expression of another gene is called ______.

epistasis

Genes located on the same chromosome that tend to be inherited together are called ______ genes.

linked

A ______ is a chart that traces the inheritance of a trait through generations.

pedigree

A chromosomal abnormality where a segment is missing is called a ______, whereas a repeated segment is called a ______.

deletion, duplication

The failure of chromosomes to separate properly during meiosis is called ______.

nondisjunction

Humans with an extra chromosome 21 have a genetic disorder called ______.

Down syndrome