Recombination is caused by-

Options

A. Crossing over alone
B. Crossing over and independent assortment
C. Independent assortment only
D. Chiasma formation

Answer

**Step-by-Step Solution:**

1. **Understanding Recombination**: Recombination refers to the process by which genetic material is rearranged during meiosis, leading to new combinations of alleles.

2. **Meiosis Overview**: Recombination occurs specifically during meiosis, which is the type of cell division that produces gametes (sperm and eggs) in sexually reproducing organisms.

3. **Identifying the Stage of Meiosis**: The key stage where recombination occurs is during Meiosis I, particularly in Prophase I.

4. **Focusing on Prophase I**: Within Prophase I, there are several stages, but the most critical for recombination is the Pachytene stage.

5. **Crossing Over**: During the Pachytene stage, homologous chromosomes pair up and exchange segments of genetic material in a process known as crossing over. This exchange results in new allele combinations.

6. **Independent Assortment**: After crossing over, during Metaphase I, the chromosomes align at the equatorial plate. The way these chromosomes are arranged and separated into daughter cells is known as independent assortment, which further contributes to genetic diversity.

7. **Conclusion**: Therefore, recombination is primarily caused by crossing over during the Pachytene stage of Prophase I in meiosis, along with the independent assortment of chromosomes during Metaphase I.

**Final Answer**: Recombination is caused by crossing over and independent assortment during meiosis.

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