logo

Cambridge IGCSE Biology practice

Paper 3 structured question: Monohybrid inheritance

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

At a glance

3

Paper

3

Marks

Topic

Monohybrid inheritance

Exam-style question

Try this first

Paper 3Theory (Core)3 marks

A pedigree chart shows the inheritance of a genetic trait in a family over three generations. Squares represent males, circles represent females, shaded symbols indicate individuals with the trait, and unshaded symbols indicate individuals without the trait.

Diagram Description

Pedigree Chart

Generation 1: One shaded circle (female) and one unshaded square (male) married. Generation 2: They have four children: one shaded square, one unshaded circle, one shaded circle, and one unshaded square. Generation 3: The shaded square from generation 2 marries an unshaded circle. They have two children: one shaded circle and one unshaded square.

GenerationIndividualSexTrait
1ParentsFemaleHas trait
1ParentsMaleNo trait
2Child 1MaleHas trait
2Child 2FemaleNo trait
2Child 3FemaleHas trait
2Child 4MaleNo trait
3Child 1FemaleHas trait
3Child 2MaleNo trait
  1. a

    Identify Which parent in generation 1 has the trait?

    Aim for approximately 1 distinct marking point.

    [1]
  2. b

    State Is the trait likely dominant or recessive? Explain your answer.

    Aim for approximately 2 distinct marking points.

    [2]

0 of 2 parts 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 3 structured question: Monohybrid inheritance

Paper 3Theory (Core)3 marks

Diagram Description

Pedigree Chart

Generation 1: Two unshaded parents (one male, one female). Generation 2: Four children: one shaded male, one unshaded female, one unshaded male, one unshaded female. Generation 3: The shaded male from generation 2 marries an unshaded female. They have two children: both unshaded (one male, one female).

GenerationIndividualSexTrait
1ParentsMaleNo trait
1ParentsFemaleNo trait
2Child 1MaleHas trait
2Child 2FemaleNo trait
2Child 3MaleNo trait
2Child 4FemaleNo trait
3Child 1MaleNo trait
3Child 2FemaleNo trait
  1. a

    Identify What type of inheritance pattern does this pedigree chart show?

    Aim for approximately 1 distinct marking point.

    [1]
  2. b

    State Why can two parents without the trait have a child with the trait?

    Aim for approximately 2 distinct marking points.

    [2]