IB Biology HL 3.1.7 Karyotyping and Karyograms
Practise IB Biology HL 3.1.7 by evaluating karyograms, chromosome fusion evidence and species-level chromosome differences.
- Syllabus
- First assessment 2025
- Course
- Biology HL
- Level
- HL
Practise IB Biology HL 3.1.7 by evaluating karyograms, chromosome fusion evidence and species-level chromosome differences.
The table shows the number of amino acids that are different in the sequences of the protein FOXP2 from a human compared with four other primate species.

Using evidence from the diagrams, justify the hypothesis that chromosome 2 in humans arose from the fusion of chromosomes 12 and 13 with a shared primate ancestor.
a. length / size of chromosome 2 in humans and 12+13 in chimpanzees is approximately equal
OR
size of the human chromosome 2 is larger than either chromosomes 12 or 13 ;
b. (bands/banding) patterns/(DNA) sequences on chromosomes 12 and 13 match chromosome 2;
c. centromere sequences present in chromosome 2 where there is no centromere OR
chromosome 2 has an additional centromere sequence (within the chromosome);
d. telomere sequence present in chromosome 2 where there is no telomere
OR
chromosome 2 has an additional telomere sequence (within the chromosome);
e. presence of telomere sequences at the predicted fusion point in human chromosome 2;
f. chromosome 12 is inverted in the short arm of chromosome 2;
4 max