different forms of a gene

allele that is always expressed if present

allele that is not expressed unless two copies (homologous) are present in an organism's genotype

two of the same alleles for a trait

having two different alleles for a trait

genetic makeup of an organism, allele combination (the letters)

physical characteristics

diagram that can be used to predict the genotype and phenotype combinations of a genetic cross

assortment of chromosomes for one trait doesn't affect the assortment of chromosomes for another trait.

when chromosomes separate in meiosis, each gamete (egg or sperm) will receive only one chromosome from each pair

a dominant (strong allele) will express itself over a recessive (weak) allele.

cross involving a single trait

cross involving two traits