Question

mendels pea plants had either purple or white flowers. this means that the plants
can self - pollinate.
have two recessive traits.
have two alleles for the gene.
have two copies of a gene from one parent.

Explanation:

1. Analyze Option 1: Self - pollination ability is not directly related to having only purple or white flowers. Self - pollination is about how the plant reproduces, not about the flower color trait's genetic basis.
2. Analyze Option 2: A plant can't have two recessive traits for flower color in a simple dominant - recessive system for this trait (purple is dominant, white is recessive in Mendel's peas). Also, the fact that there are only two phenotypes doesn't mean two recessive traits.
3. Analyze Option 3: In Mendelian genetics, for a trait like flower color, an organism has two alleles for the gene (one from each parent). The presence of two distinct phenotypes (purple or white) is related to the two alleles (dominant and recessive) for the flower color gene.
4. Analyze Option 4: Organisms get one copy of a gene from each parent, not two from one parent. So this option is incorrect.

Answer:

C. have two alleles for the gene.