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IB Biology SL A3.1.7 Karyotyping and Karyograms Questions

Construct and interpret karyograms to identify chromosome number, sex, trisomy and prenatal diagnostic evidence.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Arrange chromosomes by size, centromere position and banding pattern to construct a karyogram.
  • Interpret a karyogram to identify sex, haploid number and chromosome abnormalities such as trisomy 21.
  • Explain how chorionic-villus sampling supplies fetal chromosomes for prenatal karyotype diagnosis.

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Study A3.1.7—Karyotyping and karyograms conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

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.

Figure for Question IB Biology SL A3.1.7 Karyotyping and Karyograms Questions question 1 — IB Biology SL

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 ]

Question (b)

(b)

Describe how a karyogram is constructed.

[ 2 ]
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