Diploid representation is symbolized by which notation?

• A. 2n
• B. n
• C. 3n
• D. 4n

Answer: (A)

Diploid representation is shown as 2n because it indicates two complete sets of chromosomes—one from each parent. The n notation refers to a single chromosome set (haploid), so 2n reflects two sets, while 3n or 4n would mean three or four sets (polyploidy), not diploidy. For example, in humans, somatic (body) cells are diploid with 46 chromosomes, written as 2n = 46; gametes are haploid with 23, written as n = 23. Fertilization restores diploidy by combining two haploid genomes into a 2n zygote.