( 10 points ) You are studying wing colour in a newly discovered type of butterf
ID: 190068 • Letter: #
Question
(10 points) You are studying wing colour in a newly discovered type of butterfly. The ZW system is used in butterflies, where males are Z/Z and females are Z/W. You have two different populations of pure-breeding butterflies. One population has orange and black wings and the other has solid orange wings.
b) What does pure-breeding mean? (1 point)
You do a pair of reciprocal crosses with your two populations. CROSS A involves black and orange females crossed to solid orange males. All the F1 offspring of cross A have solid orange wings.
c) What have you learned from this cross? (1 point)
CROSS B involves a solid orange winged female and a black and orange male.
d) Predict the outcome expected if the wing colour trait is sex-linked. Use defined symbols of your choice in your explanation. (2 points)
e) Predict the outcome expected if the wing colour trait is autosomal. Use defined symbols of your own choice (2 points)
f) If the trait is sex-linked, predict the offspring expected if the F1 from cross B (described in part d, above) are interbred. (2 points)
please provide good explanations
Explanation / Answer
b) In a pure breeding oraganism, the parents always passed down a trait or phenotype to the offspring. The parents and offsprings in trub breeding will always share the same genotype.
c) in cross A, solid orange wings represent dominant character and black and orange wings means they are recessive. Let assume A= dominant, solid orange and a= recessive, black, orange. As they are purebreed, the cross was betwen dominant and recessive homozygous. The offspring will have heterozyguos phenotype and the F1 offspring will have heterozygous genotype which will show dominant phenotype.
d) If the trait is sex linke, then the male will have the genotype ZaZa and the female will have the genotype ZAW. The offspring thus will have the genotype ZA Za ( male) and ZaW ( females).
e) If the wing colour trait is autosomal then the offspring will have Aa genotype and they will show orange and black wing colour.
f) The possible genotypes of the offspring will be ZA/Za, ZA/W, Za/Za, Za/W and the ratio will be 1:1:1:1.
ZA
Za
Za
ZA Za
Za Za
W
ZA W
Za W
Half of the offspring will be male and half of the offspring will be female. Half of them will have solid orange and half will have black and orange.
ZA
Za
Za
ZA Za
Za Za
W
ZA W
Za W
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