Which statement best defines a diploid cell during meiosis?

• A. A cell containing two homologous sets of chromosomes (2n), one set inherited from each parent
• B. A cell containing a single set of chromosomes (n) that has already completed meiosis
• C. A cell containing only sister chromatids with no homologous chromosome pairs present
• D. A cell in which chromosomes have replicated so it is considered tetraploid (4n)

Answer: (A)

Verified step by step guidance

1. Understand the definition of a diploid cell: A diploid cell contains two complete sets of chromosomes, one set inherited from each parent. This is often represented as 2n, where n is the number of unique chromosomes.
2. Recall the chromosome number changes during meiosis: Meiosis starts with a diploid cell (2n), which undergoes DNA replication to form chromosomes with sister chromatids (still considered 2n but with duplicated DNA), then two rounds of division reduce the chromosome number to haploid (n).
3. Identify the key difference between homologous chromosomes and sister chromatids: Homologous chromosomes are pairs of chromosomes (one from each parent) that carry the same genes but may have different alleles, while sister chromatids are identical copies formed by DNA replication.
4. Analyze each statement in the problem: The correct definition of a diploid cell during meiosis is one that contains two homologous sets of chromosomes (2n), before the reduction divisions occur.
5. Conclude that the best statement is the one describing a cell with two homologous sets of chromosomes (2n), as this accurately defines a diploid cell at the start of meiosis.