During meiotic crossing over, which structures exchange DNA segments to produce recombinant chromatids?

• A. Homologous chromosomes as whole units without chromatid involvement
• B. Non-sister chromatids of homologous chromosomes
• C. Sister chromatids of the same chromosome
• D. Non-homologous chromosomes from different pairs

Answer: (B)

Verified step by step guidance

1. Understand the context of meiotic crossing over, which occurs during prophase I of meiosis and involves the exchange of genetic material to increase genetic diversity.
2. Recall that homologous chromosomes are pairs of chromosomes, one from each parent, that have the same genes but may have different alleles.
3. Identify that each homologous chromosome consists of two sister chromatids, which are identical copies formed during DNA replication.
4. Recognize that crossing over happens between non-sister chromatids, meaning chromatids belonging to homologous chromosomes but not identical copies of each other.
5. Conclude that the structures exchanging DNA segments to produce recombinant chromatids are the non-sister chromatids of homologous chromosomes.