Cells with only one set of chromosomes are called

• A. Diploid
• B. Haploid
• C. Genotype
• D. Allele

Answer: (B)

Having one complete set of chromosomes defines a haploid cell. In reproduction, gametes—the sperm and egg—are haploid so that when they fuse, the zygote ends up with two chromosome sets. A diploid cell, by contrast, has two sets and is typical of most body cells. Genotype refers to the specific alleles present at particular gene loci, not to the number of chromosome sets, and an allele is a variant form of a gene. So the term that describes cells with one set is haploid.