IB Biology SL 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 SL
Level
SL
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 SL A3.1.7 Karyotyping and Karyograms Questions question 1
[Maximum number: 3]
The western gorilla (Gorilla gorilla) is the largest primate. Sex determination in gorillas is the same as in humans. The image shows a karyogram of a gorilla.
Question (a)
(a)
Acrocentric chromosomes have a centromere near one end of the chromosome.
Draw a circle around the row on the karyogram that contains all acrocentric chromosomes.
[ 1 ]
third row (from the top);
Accept an arrow going to the third row or underlined. Must indicate the entire row.
Question (b)
(b)
Describe how a karyogram is constructed.
[ 2 ]
a. photograph/image of chromosomes in metaphase/mitosis/cell division; b. chromosomes arranged in (homologous) pairs; c. (pair chromosomes) according to size/length/centromere position; d. (pair chromosomes) by banding pattern;