Final answer:
The haploid number (n) for Drosophila virilis is 6, as sperm nuclei, which are haploid, contain 6 chromosomes as opposed to the 12 chromosomes found in diploid somatic cells.
Step-by-step explanation:
In Drosophila virilis, the number of chromosomes found in somatic cells differs from that found in sperm nuclei. Somatic cells contain 12 chromosomes, making them diploid, while sperm nuclei contain only 6 chromosomes, which indicates they are haploid. In this context, n represents the number of chromosomes in a haploid set. Since sperm are haploid cells and contain 6 chromosomes, n equals 6 for Drosophila virilis.
The use of the term diploid refers to a cell that contains two sets of chromosomes, one set inherited from each parent. Thus, a diploid cell has 2n chromosomes. Conversely, haploid cells, such as gametes (sperm or egg cells), contain only one set of chromosomes, represented by n. This is a fundamental concept in genetics and is consistent with the information provided for other species, such as humans, where somatic cells are diploid with 46 chromosomes and gametes are haploid with 23 chromosomes.