Mitochondrial DNA is inherited maternally.

• A. Unique to an individual
• B. Inherited maternally
• C. Found in the nucleus
• D. Degrades rapidly in light

Answer: (B)

Mitochondrial DNA is inherited maternally. This happens because the mitochondria—and their DNA—come from the egg cell, and after fertilization the offspring’s mitochondrial genome is transmitted through the maternal line. Sperm mitochondria are typically excluded or degraded, so the paternal contribution to mtDNA is minimal. That’s why mtDNA is used to trace maternal ancestry and to compare samples when nuclear DNA is degraded or unavailable. It isn’t unique to a single individual—maternal relatives share the same mitochondrial lineage for many generations. Also, mtDNA lives in the mitochondria, not the nucleus, and its relevance here isn’t about light exposure or rapid degradation.