Final answer:
The statement that mitochondrial DNA (mtDNA) is used to include or exclude someone from a bloodline on the matriarchal side is true. MtDNA is exclusively maternally inherited and is utilized by researchers to trace maternal ancestry and study evolutionary relationships.
Step-by-step explanation:
Mitochondrial DNA (mtDNA) is indeed used as a class characteristic to trace lineage on the matriarchal side, which means the statement presented in the student's question is true. Mitochondria are special organelles within our cells that have their own DNA, separate from the nuclear DNA. This DNA is maternally inherited, as it is passed down from the mother during the fertilization process.
Every living person's mitochondrial DNA is a modified copy of their matrilineal ancestor's mtDNA. It accumulates mutations over time, which allows scientists and molecular anthropologists to trace evolutionary relationships and genealogy. Mitochondrial Eve, or mtMRCA, represents the most recent common matrilineal ancestor from whom all living humans descend on their mother's side.