A Level Biology Practice Exam

What does the template strand refer to in DNA?

1. the strand that is identical to the resulting RNA strand

2. the antisense strand of DNA that serves as a template during transcription

3. the sense strand that directly encodes the protein sequence

4. a segment of RNA that is translated into proteins

The correct answer is: the antisense strand of DNA that serves as a template during transcription

The template strand in DNA refers to the antisense strand that serves as a template during transcription. During the process of transcription, RNA polymerase reads the DNA template strand to synthesize a messenger RNA (mRNA) strand. The mRNA is complementary to the template strand, which means it will have the opposite sequence of bases, thereby encoding the necessary information for protein synthesis. This relationship ensures that the correct protein sequence is produced based on the gene's DNA sequence. The other choices describe different components or relationships. One choice suggests that the strand is identical to the resulting RNA strand, which is inaccurate since the RNA is made complementary to the template strand. Another points to the sense strand encoding the protein directly; while it provides the same sequence as mRNA, it does not serve as the template during transcription. Lastly, mentioning a segment of RNA being translated into proteins does not relate to the function of the DNA template strand itself, as translation concerns RNA rather than DNA strands.