As a researcher, you were asked to grow a cell in a medium containing radioactive nucleotides, which then get incorporated into DNA. Upon later examination, the radioactivity appeared to be concentrated in the:

A-

nucleus.

B-

endoplasmic reticulum.

C-

plasma membrane.

D-

peroxisome.

Nucleus

Explanation:DNA (Deoxyribonucleic acid) is a genetic material and carries the genetic information from one generation next generation. It restores the species identity. The Double helical model of DNA was given by the James Watson and Francis Crick in 1953 based on the Chargoff's rules and X-ray diffraction data of Wilkins and Franklins. According to them, two polynucleotide chains run twist around each other form right-handed double helix. Each nucleotide made up of a nitrogenous base, deoxyribose sugar, phosphate moiety.

The nucleus is a master control center of the cell and it was first discovered by the Robert Brown. It is a membrane-bound organelle harbor the genetic material called DNA. The integrity of DNA is maintained by the nucleus. When the cells are grown in radioactive nucleotides containing a medium, all the radioactive nucleotides are incorporated into the DNA, which is located in the nucleus so most of the radioactivity concentrated in the nucleus of the cell.