Catalase is an enzyme that decomposes hydrogen peroxide within cells. Red blood cells contain catalase. In some dogs, an inherited disorder means catalase is not made. This disorder is called acatalasia, and it results from a mutation in the gene for catalase.
(a)[2]
Define the terms gene and gene mutation.
(b(i))[3]
State the genotypes of the dogs labelled 1, 2 and 3 in Fig. 3.1.
(b(ii))[3]
Complete the genetic diagram to show how this is possible.
(b(iii))[1]
State the name given to the type of cross that you carried out in (b)(ii).
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Gene: a stretch of DNA that codes for a protein” …