Biology Answers

QUESTION THIRTEEN: GENETICSA pure breeding homozygous dominant short haired Siamese catis mated with a long haired recessive cat.ANSWER THIRTEEN: GENETICSa) Pure breeding means that an organism is homozygous for that traitb)llLLLl LlLl LlGenotype: LlPhenotype: all short haired(a)Long-haired SiameseDefine pure breeding.Short-haired Siamese(b) Complete the Punnett square for the cross described aboveand state the genotype and phenotype of the offspring (kittens).Use the letter L and l.(c) A breeder wishes to have an equal mixture of both longhaired and short haired Siamese kittens to sell. Explain how shecould best ensure that this occurs.c) Explains that a heterozygous short haired cat and a long haired cat is needed(or draws a Punnett square to show this) and then discusses the chance ofgetting either kitten.E.g. In order to have a mixture of both long haired and short haired kittens thebreeder would have to find a heterozygous short haired cat to mate with a longhaired cat (or 2 heterozygous individuals)llLlLl llLl llThen she would have a 50% chance of getting either long haired or short hairedkittens. Since cat litters are relatively large (5-8 kittens) then there should be avariety of both. (Recognises that Ll x ll is a better ratio than Ll x Ll for the mix ofphenotypes in the kittens)For Achievement your answer should have TWO correct statements.a) Correct definitionb) Either correct Punnett square (or genotype and phenotype correct forincorrect Punnett square)c) Recognises the need for a heterozygous individualFor Merit your answer should have both of:b) Correct Punnett square and correct genotype and phenotypec) Explains that a heterozygous short haired cat and a long haired cat isneeded (or draws a Punnett square to show this).Also may have 2 heterozygous individuals mating Ll x LlFor Excellence your answer should have both a) and b) and a fulldiscussion for c)