text: one freaking bio question i am not sure about. dna rna? a professor has been isolating and purifying dna and rna from a variety of organisms.  the label on one of the tubes has fallen off.  what sort of a test can she run to determine if the tube contains dna?     a. a test for the presence of adenine.   b. a test for the presence of guanine.   c. a test for the presence of cytosine.   d. a test for the presence of thymine.    e. a test for the presence of uracil. both rna and dna contain adenine, guanine and cytosine  only dna has thymine and only rna has uracil  therefore it would be d that tells the professor if theres a presence of dna