Question

Study of the mitochondrial DNA of present day Native Americans points to _________.

a. The impossibility of their being related to East Asians who crossed the Beringia land bridge around 25,000 years ago.
b. The incompleteness of the human genome, at least at present.
c. A gap of roughly 10,000 years between the emergence of their genome in Siberia, and its transfer to the Americas.
d. The imprint of a bacterial infection that was acquired when one individual sailed across the Pacific to the vicinity of modern-day Seattle.

Answer 1

a. The impossibility of their being related to East Asians who crossed the Beringia land bridge around 25,000 years ago.

Mitochondrial DNA studies of present-day Native Americans provide evidence of their connection to East Asians who migrated via the Beringia land bridge approximately 25,000 years ago, with a time gap of about 10,000 years between this emergence and their settlement in the Americas.

Step-by-step explanation:

The study of the mitochondrial DNA (mtDNA) of present-day Native Americans supports the theory that there is a link between them and East Asians who crossed the Beringia land bridge around 25,000 years ago. This mitochondrial DNA evidence aligns with the Bering Land Bridge migration model, suggesting that during the last ice age, humans moved from Siberia to Alaska across a land bridge, and subsequently populated the Americas. This is further corroborated by genetic markers found on the Y chromosome shared between Asians and Native Americans. Consequently, the correct answer to the student's question is 'c', indicating that there was a gap of roughly 10,000 years between when the mitochondrial genome emerged in Siberia and its transfer to the Americas.