Mendel verified true-breeding pea plants for certain traits before undertaking his experiments. The term "true-breeding" refers to:

1. genetically pure lines.
2. organisms that have a high rate of reproduction.
3. organisms that will produce identical copies of themselves upon reproduction.
4. organisms that are heterozygous for a given trait.
5. organisms that are homozygous for all possible traits.

genetically pure lines.

The physical appearance of an organism for a given trait is termed:

1. genetics.
2. dominance.
3. synapsis.
4. genotype.
5. phenotype.

phenotype