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IB Biology HL 2.3.10 Non-disjunction and karyotype analysis Question Bank

Practise IB Biology HL 2.3.10 by analysing karyograms and meiotic mechanisms that produce aneuploidy.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Identify the meiotic stage and chromatid error responsible for non-disjunction.
  • Use karyotype evidence to diagnose chromosome abnormalities and their origin.

D2.1.10—Down syndrome question 1

[Maximum number: 1]

In a strain of soybeans, high oil content (H) in seeds is dominant to low oil content (h) and four seeds in a pod (F) is dominant to two seeds in a pod (f). A farmer crosses two soybean plants, both with high oil content and four seeds in a pod. The offspring have a phenotypic ratio of 9: 3: 3: 1.

The image shows the karyotype of a person who developed as a female.

Figure for Question D2.1.10—Down syndrome question 1 — IB Biology HL

Determine, with a reason, whether this karyotype shows that non-disjunction has occurred.

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