Question

You're a Pokemon breeder. You recently crossed a purple eared, yellow Pikachu to a black eared, green Pikachu. Both parents have two stripes on their tails. The offspring obtained from the first two litters in this cross had the following characteristics: All of the offspring were yellow. 8 had purple ears and one stripe on their tails. 6 had black ears and one stripe on their tails. 21 had purple ears and two stripes on their tails. 25 had black ears and two stripes on their tails.

a. For each character, report which trait is likely recessive and which is dominant (this may not be possible for all characters).

b. What are the genotypes of the parents that could give you this result?

c. Given your answers to a and b, what are the expected number of offspring per phenotype? Can you reject independent assortment of these genes given the original observed numbers from above? Provide statistical evidence to support your answer.

d. Assuming you produced another litter of 6 animals from these parents, what is the probability of obtaining the following offspring: 3 with two stripes and black ears, 2 with one stripe and purple ears, 1 with 1 stripe and black ears.

**The stripes and the ear colors are the traits we're focusing on, and we don't know if the parents are homozygous or heterozygous that's what we have to guess at on part b

Answer 1

a) given number of offspring are

offspring with purple ear and one stripes on their tail=   8

                            black ear and one stripes on their tail = 6

                           purple ear and two stripes on their tail= 21

                           black ear and two stripes on their tail = 25

considering trait independently ,

number of offspring with one stipe = 14

number of offsprings with two stripes= 46

there ratio is = 46:14 = 3.3 :1 which is very near to ratio 3:1, therefore two stipes is dominant trait and one stripe is recessive trait.

similarly for ear colour

number of offspring with purple ear = 29

number of offsprings with black ear = 31

their ratio= 31:29 = 1.06:1 which is very near to 1:1 therefore either colour could be dominant or recessive.

b) from both ratio we can conclude that both the parents are heterozygous for strip trait while either one of them are heterozygous for ear colour while other is recessive for ear colour.

C) total offspring is = 60

expected number of offspring for both the colour ear =30

expected number of offspring for two strip = 45 and expected number of offspring with 1 stripe = 15

chi square for each trait for this data and look for probability of accecptance of theory in chi square distributaion table.