Answer:
Plasmid DNA play a important role for survival of a prokaryotic cell.
Option D is correct one.
Explanation:
In addition to the chromosome, many prokaryotes have plasmids, which are small rings of double-stranded extra-chromosomal ("outside the chromosome") DNA. Plasmids carry a small number of non-essential genes and are copied independently of the chromosome inside the cell. They can be transferred to other prokaryotes in a population, sometimes spreading genes that are beneficial to survival.
For instance, some plasmids carry genes that make bacteria resistant to antibiotics. (These genes are called R genes.) When the plasmids carrying R genes are exchanged in a population, they can quickly make the population resistant to antibiotic drugs. While beneficial to the bacteria, this process can make it difficult for doctors to treat harmful bacterial infections.
In the case of the gene that determines high cholesterol in the blood, the two alleles express incomplete dominance.
What this means is that the dominant allele is not completely dominant over the recessive allele. If the allele was completely dominant, even one allele would be enough to determine the individual's trait as dominant. But in the case of incomplete dominance between the alleles, the heterozygous individuals that have one dominant and one recessive allele are an ''in between'' phenotype.
A basic tenet of modern biology, first stated by Matthias Schleiden and Theodor Schwann in 1838–39, that cells<span> are the basic units of structure and function in living organisms. ... A </span>theory<span> of heredity must be reconciled with the </span>cell theory<span>.</span>
