Trait - distinguishing characters or phenotypic features of an individual. (e.g. Blue eyes, black hair, etc.) Purebreed - having descended from ancestors of a distinct type or breed. Purebreed organisms in a given species or variety all share similar traits. (e.g. Purebred dog.) P Generation - Designation given to the parent generation.
F1 and F2 generation - First and second filial generation.
First Filial Generation - offspring from the cross of the P generation. Second Filial Generation - offspring of the first filial generation. Hybrid - an organism is heterozygous for a trait.
Monohybrid - a cross of two heterozygous individuals that differ in one trait. (Aa * Aa) Product Rule - the probability or chance that two or more independent events will occur together is the product of their individual probabilities of occurring alone. Punnett Square - simple grid used to illustrate all possible combinations of gametes from a given set of parents. (See "Punnett Square 08-01-13.png") Genotype - genetic makeup of an organism. It remains constant throughout an individual's life, and is indicated by a combination of letters. Phenotype - the physical or physiological traits of an organism.
A test cross is a cross of an individual of an unknown genotype with a homozygous recessive individual, used as a method to determine the unknown genotype.
This is how you determine if a particular organism is a homozygous dominant or heterozygous.
Note: It is impossible to determine the genotype of an organism that is expressing the dominant trait simply by looking at their appearance. P. 534, test cross.
Blending of the traits of two different alleles at one locus that occurs when neither allele is dominant. Co-Dominance
Two alleles may be expressed equally. The situation occurs when two different alleles for a trait are both dominant. Ex. Feather colour in chicken - black birds are homozygous for B, and...
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