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Clarify how to perform a test cross to determine an unknown genotype.

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Cambridge IGCSE BiologyInheritanceSupplement content

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Clarify how to perform a test cross to determine an unknown genotype

  • This point belongs to Monohybrid inheritance, especially Monohybrid inheritance outcomes.
  • You need to be able to clarify how to perform a test cross to determine an unknown genotype.
  • The key ideas to know are Explain.
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Explain

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This objective helps connect Monohybrid inheritance outcomes to exam-style questions, flashcards, and revision notes for Monohybrid inheritance.

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Paper 4 structured question: Monohybrid inheritance

Paper 4Theory (Extended)3 marks

Description

Test Cross Procedure

A plant shows a dominant trait, but its genotype is unknown. To find out, it is crossed with a plant that is homozygous recessive for the same trait. The offspring are then observed for their phenotypes.

  1. a

    Explain how this test cross can determine the unknown genotype of the plant showing the dominant trait.

    Aim for approximately 3 distinct marking points.

    [3]
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