logo

Cambridge IGCSE Biology practice

Paper 4 structured question: Monohybrid inheritance

Try the question first, then check the answer and practise the same topic again.

Attempt questionMonohybrid inheritance revisionRevise the key idea

At a glance

4

Paper

3

Marks

Topic

Monohybrid inheritance

Exam-style question

Try this first

Paper 4Theory (Extended)3 marks

Determining the genotype of an organism showing a dominant trait.

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]

0 of 1 part answered

Answer every part before opening the mark scheme.

Common mistake

No common mistake is linked to this question yet.

Related flashcards

Flashcard 1 of 6

Press Space to flip, arrows to move

Related practice questions

Question 1 of 5

Choose an answer, get feedback, then move sideways through the set.

0 of 4 attempted

Paper 4 structured question: Monohybrid inheritance

Paper 4Theory (Extended)3 marks

Data Table

Offspring Phenotypes from a Test Cross

A plant with an unknown genotype showing a dominant trait is crossed with a homozygous recessive plant. The following offspring were observed:

PhenotypeNumber of Offspring
Dominant trait50
Recessive trait50
  1. a

    Identify the genotype of the unknown parent plant based on the offspring data.

    Aim for approximately 1 distinct marking point.

    [1]
  2. b

    Explain why the offspring show this ratio of phenotypes.

    Aim for approximately 2 distinct marking points.

    [2]