Which term describes a cell that contains only a single set of chromosomes and therefore only a single set of genes (Humans N = 23)?

• A. Diploid (2N)
• B. Monoploid
• C. Polyploid
• D. Haploid (N)

Answer: (D)

Having a single complete set of chromosomes means the cell is haploid. In humans, a haploid cell carries 23 chromosomes, one copy of each chromosome, so there is only one allele for many genes. This is the state of the gametes—sperm and egg. When fertilization occurs, the haploid genomes merge to form a diploid zygote with two copies of each chromosome (46 total). The term for cells with two complete sets is diploid, and for more than two sets it’s polyploid. Monoploid is a less common term that can describe the same idea in some contexts, but the standard label for a single chromosome set in humans is haploid.