Question

AP

Question 4 In the tongue sole fish (Cynoglossus semilaevis), sex is determined by a combination of genetics and environmental temperature. Genetically male fish have two Z chromosomes (ZZ), and genetically female fish have one Z chromosome and one W chromosome (ZW). When fish are raised at 22°C, ZZ fish develop into phenotypic males and ZW fish develop into phenotypic females. However, when fish are raised at 28°C, the Z chromosome is modified (denoted as Z*). Z*W individuals develop as phenotypic males that are fertile and can pass on the Z* chromosome to their offspring even when the offspring are raised at 22°C. A cross between a ZW female and a Z*Z male is shown in the Punnett square below. Z* Z W Z* Z Z* W ZZ | ZW z Predict the percent of phenotypic males among the F1 Offspring of the cross shown in the Punnett square if the offspring are raised at 22°C. B I v E 0 / 10000 Word Limit

Answer 1

Hi! .

the Z chromosome is changed to Z* at 28 degreees and the male who has a Z* in his genotype can transmit it to offsprings even at 22 degrees. So in the above cross between Z*Z male and ZW female the F1 generation will be Z*Z , Z*W , ZZ ,ZW.

in which

Z*Z is female even at 22 degrees.

ZW is female

ZZ is male

Z*W is male

%phenotypic males will be 50%