Prophase I features includes crossing over between homologues. Choose the accurate description.

Prophase I features includes crossing over between homologues. Choose the accurate description.

• A. Chromosomes condense and pair, crossing over occurs.
• B. Sister chromatids separate.
• C. Spindle fibers disappear.
• D. The cell becomes diploid G2 stage.

Answer: (A)

During prophase I of meiosis, homologous chromosomes condense and pair together through synapsis to form tetrads, and crossing over occurs between non-sister chromatids. This exchange of genetic material at chiasmata creates recombinant chromatids, increasing genetic diversity in the gametes. The described combination of condensing, pairing, and crossing over is the defining feature of this stage. The other statements don’t fit: sister chromatids separate later, not in prophase I; spindle fibers form rather than disappear; and the cell remains diploid before meiosis begins (G2 is just before meiosis, after S phase), so it doesn’t “become” diploid at that stage.

During prophase I of meiosis, homologous chromosomes condense and pair together through synapsis to form tetrads, and crossing over occurs between non-sister chromatids. This exchange of genetic material at chiasmata creates recombinant chromatids, increasing genetic diversity in the gametes. The described combination of condensing, pairing, and crossing over is the defining feature of this stage. The other statements don’t fit: sister chromatids separate later, not in prophase I; spindle fibers form rather than disappear; and the cell remains diploid before meiosis begins (G2 is just before meiosis, after S phase), so it doesn’t “become” diploid at that stage.