ex. 45 [principles of heredity]

• alleles: different molecular versions of genes coding for the same traits
• homozygous: having two identical alleles of a particular gene, e.g. BB
• heterozygous: having two different alleles of a particular gene, e.g. Bb
• dominant: an allele that is expressed when present as either homozygous or heterozygous, e.g. B
• recessive: must be present in double dose to show its traits
• genotypes: the genetic makeup of an organism, expressed as a combination of alleles
• phenotype: the physical expression of a gene, the phenotype is the result of the interaction of the genotype and the environment
• incomplete dominance: both alleles express themselves in offspring