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