The edible pea (Pisum sativum) has a diploid number of 14 - VCE - SSCE Biology - Question 4 - 2007 - Paper 1

To determine the number of DNA molecules at the beginning of meiosis, we start with the diploid number of the organism. In this case, the edible pea has a diploid number of 14, indicating that it has 14 chromosomes.

During meiosis, the DNA is replicated during the S phase of the cell cycle before the actual meiotic divisions begin. Therefore, each chromatid replicates, resulting in two sister chromatids for each chromosome.

At the beginning of meiosis, the number of DNA molecules is doubled because each chromosome consists of two chromatids. Thus, the calculation is:

egin{align*} ext{Number of DNA molecules} &= 2 imes ext{Diploid number} \ &= 2 imes 14 \ &= 28 ext{Thus, the correct answer is D. 28.}

In summary, one cell in the ovary undergoing meiosis starts with 28 DNA molecules.