The number of chromosomes in a gamete is represented by

Analyze the question The question asks how the chromosome number in a gamete (sex cell, such as a sperm or an egg) is represented.

Explain the concept

• Body (somatic) cells are diploid, written 2n. They contain two sets of chromosomes, one from each parent. In humans, 2n = 46.
• Gametes are haploid, written n. They contain only one set of chromosomes. In humans, n = 23.
• Gametes are formed by meiosis, which halves the chromosome number from 2n to n.
• At fertilisation, a haploid sperm (n) fuses with a haploid egg (n) to form a diploid zygote (2n). This restores the full chromosome number and keeps it constant from generation to generation.

Show the solution

1. Gametes are produced by meiosis (reduction division).
2. Meiosis reduces the chromosome number by half: 2n → n.
3. So a gamete has n chromosomes. For humans, that is 23.

Checking the options

• A. n – haploid number, correct for gametes.
• B. 2n – diploid number, found in body cells and the zygote.
• C. 4n – tetraploid, a polyploid condition, not normal for gametes.
• D. 23n – not a valid way to write chromosome number. 23 is the value of n in humans, not a multiple of it.
• E. 46n – also invalid, because 46 is the value of 2n in humans.

Answer: A (n)

Tip: Remember "Gametes are Haploid, n" (G–H–n). Body cells are 2n. Fertilisation is n + n = 2n. If an option has a number in front of the n, like 23n or 46n, it is usually a distractor.