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nmdcat.online July 14, 2026

Which of the following is a major source of heritable variation in sexually reproducing organisms that Darwin observed but could not genetically explain?

A. Mitotic division of somatic cells
B. Independent assortment of chromosomes and crossing over during meiosis
✓
C. The transcription of mRNA from template DNA
D. The physical wear and tear of tissues during an organism's life

📝 Explanation

Meiotic processes (independent assortment, crossing over, and random fertilization) shuffle alleles to create unique genetic combinations, producing the heritable variation key to selection.

📖 Additional Information

  • Mitotic division of somatic cells
  • Independent assortment of chromosomes and crossing over during meiosis
  • The transcription of mRNA from template DNA
  • The physical wear and tear of tissues during an organism's life

Meiotic processes (independent assortment, crossing over, and random fertilization) shuffle alleles to create unique genetic combinations, producing the heritable variation key to selection.

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