Practise family pedigree questions by working from symbols and affected relatives to determine genotypes, carriers and genetic-control claims.
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.
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.
How many individuals in this family have the genotype Nn ?
2
4
5
6