Question

1. A pea plant with genotype TtggFFRr is test corssed.

A) What is the genotype of the test parent ?  

B) What would be the probability of offspring with genotype ttggFfrr ?

Answer 1

Answer to Question :

Test cross can be defined as a cross between the parental homozygous recessive individual with any other individual to determine if they're heterozygous or homozygous dominant.

Answer to Part A) So going by the definition, the genotype of the test parent will be homozygous recessive which will be ttggffrr.

Answer to Part B ) Now we've to cross the given pea plant with the test parent. For that matter, we'll first find out types of possible gametes for both the individual. We'll use fork line method. Parental gametes will be all similar and of one type tgfr but the pea plant which is being test crossed will produce four different types of gametes. You can see in my handwritten solution.

Then using punnet square method we'll find out the proportion of individual with the genotype ttggFfrr. We can easily see that they exist in a ratio of 1:4 or they are 25 percent of all the offspring possible.