Question

In recent years, DNA sequences (nucleotide sequence) of mt-DNA and Y chromosomes were considered for the study of human evolution, because
A. They are small and therefore easy to study.
B. They are uniparental in origin and do not take part in recombination.
C. Their structure is known in great detail
D. They can be studied from the samples of fossil remains.

Answer 1

Hint: Mitochondrial DNA or mt- DNA consisting of several unique properties have made it the molecular choice for the study of human evolution. It shows maternal inheritance that transfers from generation to generation without any changes. Whereas the Y chromosome is only present in males and makes it separable for evolution studies in humans.

Complete answer:
Mitochondrial DNA is a small circular genome found in a cell organelle called mitochondria. The scientists named Wilson and Sarich were chosen to study human evolution.
They are uniparental in origin and never participate in recombination. Mitochondrial DNA accommodates preserved sequences of DNA that don't participate in recombination and additionally they show maternal inheritance that is carried from generation to generation without any changes in the sequence of DNA thus mitochondrial sequences are typically studied for evolution in a human body.

Few unique properties of mitochondrial DNA (mt-DNA) are -
-Large copy numbers
-Inheritance from mother or we can say maternal inheritance
-Higher rate of mutation

Y chromosome (sex chromosome) is present only in male therefore throughout reproductive cell formation specific region of Y chromosome takes half in recombination referred to as pseudoautosomal region so the rest of the sequence of Y chromosome remains unchanged and is carried from generation to generation and is thus preserved. Thus Y chromosome also is used for the study of human evolution because the sequences area unit preserved and recombination don't occur in most a part of the sequences of DNA. Preserved sequences of DNA will surely be used to study evolution by a comparative analysis of the order.

Hence, the correct answer is option (B).

Note: Both mitochondrial DNA (mt-DNA) and Y chromosome shows some unique properties like they both are uniparental in origin means originated from one parent only. mt-DNA from mother and Y chromosome from father. Besides that, they don't take part in the process of recommendations and hence several parts of it remain unchanged that can be used for the study of human evolution because it transfers from generation to generation without any changes in it.