1 In cow horned is a recessive trait polled hornless is domi

1) In cow, horned is a recessive trait, polled (hornless) is dominant. You cross two polled animals that both had a horned mother. In their progeny, you pick a polled steer. What is the probability that this steer is heterozygous? (2/3)

2) In the progeny of an F1 plant you expect four phenotypes resulting from the genetic action of dominant and recessive alleles at two independent genes. Out of 50 F2s, you count 27 double dominant, 7 and 9, respecitively, single dominants, and 7 double recessive phenotypes. What Chi Square value do you calculate for this outcome and do you reject the above hypothesis? (5.5, no)

3) A plant that is heterozygous for gene A is self-fertilized, and all the resultant offspring are continually self fertilized for another 4 generations. How many offsprings would you expect to be homozygous for gene A in the 4th inbreeding generation? (~94%)

4) A plant that is heterozygous for gene A is self-fertilized, and all the resultant offsprings are continually self fertilized for another 5 generations. How many offpsrings would you expect to be homozygous dominant for gene A in the 5th inbreeding generation? (~48%)

I have included the answers in the parenthesis after each questions. Please let me know how you got those answers in detail please :)

Solution

Answer:

(1)

Polled =P

Horned =p

Scenario 1:

P1 = PP(polled) x pp (horned)

F1 = Pp (all progeny are polled, heterozygous)

F2 = Pp x Pp

P

p

P

PP (polled)

Pp (polled)

p

Pp (polled)

Pp (horned)

2/3 are heterozygous polled steer