84 NCEA Style Question: Inheritance of Alleles 85 KEY TERMS AND IDEAS:

1. Snapdragons have red, pink, or white flowers. Roan coats in Shorthorn cattle is a mix of red and white hairs.

(a) Define monohybrid cross:

(b) Use the inheritance patterns of codominance and incomplete dominance to explain these results (you may use extra paper if required):

2. A Drosophila male with genotype Cucu Ebeb (straight wing, grey body) is crossed with a female with genotype cucu ebeb (curled wing, ebony body). The phenotypes of the F1 were recorded and the percentage of each type calculated.

The percentages were straight wings, grey body 45%, curled wings, ebony body 43%, straight wings, ebony body 6%, and curled wings grey body 6%.

(a) What are the phenotypic characteristics being investigated here?

(b) What sort of cross is this? Justify your answer:

(c) Is there evidence of crossing over in the offspring?

(d) Explain your answer:

(e) Determine the genotypes of the offspring:

Straight wing: Cucu Grey body: Ebeb Curled wing: cucu Ebony body: ebeb

3. In guinea pigs, black hair (B) is dominant over white hair (b) and short hair (L) is dominant over long hair (l). Breeders use true breeding parents in order to produce consistent and reliable coat colour in guinea pigs. A breeder has a male guinea pig she knows to be BBLL and a female she knows to be bbll. She wants to use them to begin a breeding programme to produce a true breeding white, short haired guinea pig. In your answer you should include:

• A definition of true breeding • Relevant genotypes and phenotypes • The use of a Punnett squares and the correct use of the allele notation given • An explanation of how the desired pure breeding animal can be produced • An explanation of how the animal's ability to breed true could be proved.