IB Biology HL A3.1.7 Karyotyping and Karyograms Questions
Karyotypes show chromosome number and structure in a cell. Karyograms arrange chromosomes by length, banding pattern and centromere position; human chromosome 2 provides evidence of fusion from two ancestral ape chromosomes.
Syllabus
First assessment 2025
Course
Biology HL
Level
HL
Exam points
Use a karyotype to identify chromosome number and structure in a cell.
Arrange chromosomes in a karyogram by length, banding pattern and centromere position.
Explain how human chromosome 2 supports fusion from two ancestral ape chromosomes.
IB Biology HL A3.1.7 Karyotyping and Karyograms Questions question 1
[Maximum number: 4]
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;