20
2. Why do mitochondria and chloroplast have their own DNA separate
from the nucleus?

Chloroplasts have their own DNA, often abbreviated as cpDNA. It is also known as the plastome when referring to genomes of other plastids. Its existence was first proven in 1962. The first complete chloroplast genome sequences were published in 1986, Nicotiana tabacum (tobacco) by Sugiura and colleagues and Marchantia polymorpha (liverwort) by Ozeki et al. Mitochondria of most organisms still have their own DNA because the genetic code for mitochondria is different from that of nuclear DNA in most organisms in which has been tested. This is the reason that mtDNA structural genes (i.e. those that code for proteins) have transferred to the nucleus so slowly after the original symbiotic relationship developed.

Explanation:

I think C or D

But choose D

hope this helped

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.