Question

which of the following is a key difference between dna and rna?
a. dna contains deoxyribose sugar, rna contains ribose sugar.
b. dna has thymine, rna has uracil.
c. dna is double - stranded, rna is single - stranded.
d. all of the above.

Explanation:

• Option a: DNA has deoxyribose sugar (missing an oxygen atom at the 2' - carbon of the sugar ring compared to ribose), while RNA has ribose sugar. This is a correct difference.
• Option b: DNA contains thymine (\(T\)) as one of its nitrogen - containing bases, and RNA contains uracil (\(U\)) instead (while both have adenine (\(A\)), guanine (\(G\)), and cytosine (\(C\))). This is a correct difference.
• Option c: DNA is typically double - stranded (in a double - helix structure), and RNA is usually single - stranded (though some RNAs can have secondary structures with base - pairing, but the general strand - number difference holds). This is a correct difference.

Since all of the options (a, b, and c) describe valid key differences between DNA and RNA.

Answer:

d. All of the above.