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Edexcel IGCSE Biology 3.24 Interpreting Family Pedigrees Questions

Practise reading pedigree symbols to infer genotypes and carrier status, count heterozygous relatives, and predict offspring sex and phenotype ratios.

Syllabus
First assessment 2019
Course
Biology 4BI1

Exam points

  • Infer family members’ genotypes from pedigree symbols, affected status and known inheritance patterns.
  • Count heterozygous individuals in a pedigree from the stated allele inheritance and affected relatives.
  • Complete a pedigree by applying parental inheritance probabilities to predicted offspring sex and phenotype ratios.

Edexcel IGCSE Biology 3.24 Interpreting Family Pedigrees Questions question 1

[Maximum number: 1]

Reflexes are responses that protect the body and involve the central nervous system (CNS).

The photograph shows a breed of dog called a border collie.

Figure for Question Edexcel IGCSE Biology 3.24 Interpreting Family Pedigrees Questions question 1 — Edexcel IGCSE Biology

Some border collies have a genetic condition called sensory neuropathy.
Border collies with sensory neuropathy may be injured as their reflexes do not work well.

Sensory neuropathy is caused by a recessive allele, n . The dominant allele for not having sensory neuropathy is N .

The diagram shows a family pedigree for some border collies.

Figure for Question Edexcel IGCSE Biology 3.24 Interpreting Family Pedigrees Questions question 1 — Edexcel IGCSE Biology

How many individuals in this family have the genotype Nn ?

A

2

B

4

C

5

D

6

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