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IB Biology HL 3.2.21 Chi-squared test Question Bank

Practise IB Biology HL 3.2.21 by applying chi-squared test concepts to exam-style questions.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • identify the relevant biological structure, process or evidence
  • apply the correct biological mechanism to the question
  • evaluate the result using data, adaptation or ecological reasoning

D3.2.21 (HL)—Chi-squared test question 1

[Maximum number: 2]

The diagram shows one of Thomas Hunt Morgan's crosses of Drosophila in the early 20th century.

Figure for Question D3.2.21 (HL)—Chi-squared test question 1 — IB Biology HL

The chi-squared value was calculated as shown. Deduce, with reasons, whether the observed ratio differed significantly from the expected Mendelian ratio.

c2=Σ( Observed − Expected )2 Expected =1002.6c^{2}=\Sigma \frac{(\text { Observed }- \text { Expected })^{2}}{\text { Expected }}=1002.6
Table for Question D3.2.21 (HL)—Chi-squared test question 1 — IB Biology HL
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