A Levels Biology (9700)•9700/11/M/J/20
Explanation
Calculating thymine bases from total strand length Steps:
- DNA is 15 base pairs long, so each strand has 15 nucleotides.
- Strand 1 has A = 6, C = 3, G = 4 nucleotides.
- Sum of known bases: 6 + 3 + 4 = 13.
- Thymine bases (T) = 15 - 13 = 2. Why A is correct:
- Total nucleotides per strand equals base pairs (15), so T = total - (A + C + G) by conservation of strand length. Why the others are wrong:
- B: 3 is the count of cytosine (C) bases.
- C: 4 is the count of guanine (G) bases.
- D: 6 is the count of adenine (A) bases.
Final answer: A
Topic: Structure of nucleic acids and replication of DNA
Practice more A Levels Biology (9700) questions on mMCQ.me