Final answer:
A pea plant that is homozygous for yellow seeds (YY) will produce gametes that are Y only, due to its two identical Y alleles for seed color.
Step-by-step explanation:
If a pea plant is homozygous for yellow seeds (YY), the gametes it will produce are Y only. This is because being homozygous means the plant has two identical alleles for seed color, in this case, Y. During gamete formation, each gamete receives one allele for each gene, and since both alleles in this plant are Y, all gametes will receive a Y allele.
Understanding Mendelian genetics and how traits are passed on through alleles, we know that a plant with a homozygous YY genotype can only produce Y gametes. This is true because each gamete carries only one allele for the trait, and this plant has only Y alleles to give.
A homozygous pea plant with the genotype YY will produce only gametes with the Y allele, so the answer is A. Y only. In a self-cross with another homozygous plant with the same genotype (YY), the resulting offspring will also have the genotype YY.