Question

Sequence of which of the following is used to know the phylogeny?
A. mRNA
B. rRNA
C. tRNA
D. DNA

Answer 1

A putative link between groups of creatures referred to as phylogeny. Carl Woese came up with the idea of life supporting his discovery that the genes encoding ribosomal RNA are ancient and distributed over all lineages of life with little or no gene transfer. More conserved sequences are likely to be more useful.

Complete answer:
Option A: mRNA is the messenger RNA , a molecule in cells that carries codes from the DNA within the nucleus to the sites of protein synthesis within the cytoplasm. It is only utilized in the Transcription process and it doesn't tell about Phylogeny.
So, option A is not correct.
Option B: rRNA is the ribosomal RNA, the genes for rRNA tend to be highly conserved for primer design and hypervariable regions to spot phylogenetic characteristics of micro-organisms and are often employed for phylogenetic studies, because of slow rates of evolution of genes of this region.
So, option B is correct.
Option C: tRNA is the transfer RNA , a kind of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein. tRNAs function at specific sites within the ribosome during translation.
So, option C is not correct.
Option D: DNA is the hereditary unit. It allows hereditary information to be passed from one generation to subsequent. Gene transfer is taking place here.
So, option D is not correct.

Therefore, Option B is the correct answer.

Note:
The $16S$ rRNA gene sequence became the foremost widely used marker gene for profiling bacterial communities. rRNA is a really important factor to determine Homology, to determine relationships between various organisms. Such molecules are considered as ancestral characters, and also are very useful to review Chemotaxonomy. Therefore, rRNA is commonly encouraged as molecular clocks to the phylogeny.