Which statement defines a diploid cell?

Which statement defines a diploid cell?

• A. A cell with a single set of chromosomes
• B. A cell with two identical copies of each chromosome
• C. A cell that contains both sets of homologous chromosomes
• D. A cell with no chromosomes

Answer: (C)

Diploid means the cell has two complete sets of chromosomes, one from each parent. For every chromosome type, there is a pair of homologous chromosomes present, carrying the same genes in the same order but often with different alleles. This is what makes a cell diploid: two sets, two versions of each chromosome. The other descriptions don’t define diploidy. A single set describes a haploid cell; no chromosomes would be an empty or nonfunctional state; two identical copies would imply sister chromatids or perfectly identical homologs, which isn’t the standard definition of having two chromosome sets. In many organisms, including humans, this two-set arrangement in somatic cells contrasts with the single-set gametes produced in meiosis.

Diploid means the cell has two complete sets of chromosomes, one from each parent. For every chromosome type, there is a pair of homologous chromosomes present, carrying the same genes in the same order but often with different alleles. This is what makes a cell diploid: two sets, two versions of each chromosome.

The other descriptions don’t define diploidy. A single set describes a haploid cell; no chromosomes would be an empty or nonfunctional state; two identical copies would imply sister chromatids or perfectly identical homologs, which isn’t the standard definition of having two chromosome sets. In many organisms, including humans, this two-set arrangement in somatic cells contrasts with the single-set gametes produced in meiosis.