| Date | May 2017 | Marks available | 1 | Reference code | 17M.1.SL.TZ1.21 |
| Level | Standard level | Paper | Paper 1 | Time zone | Time zone 1 |
| Command term | Question number | 21 | Adapted from | N/A |
Question
Cladograms can be created by comparing DNA or protein sequences. The cladogram on the left is based on DNA sequences and the cladogram on the right is based on comparing protein sequences.
What is the reason that cladograms based on DNA sequences are more reliable predictors of the phylogenetic relationship of species than cladograms based on protein sequences?
A. Amino acids are not as chemically stable as DNA nucleotides.
B. DNA mutates but amino acids do not.
C. Several different triplets of bases can code for the same amino acid.
D. There are 20 different amino acids but only 4 nucleotides.
Markscheme
C
Examiners report
[N/A]
Syllabus sections
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