2 If you found a W warhawkiensis plant with large purple flo

2. If you found a W. warhawkiensis plant with large purple flowers, how could you determine its genotype? Describe the cross that you would use and all of the possible outcomes (eg. ‘If the genotype is _/_; _/_, then the outcome of the cross will be ….’.). Cross: Possible outcomes:

3. Short fur in cats is dominant to long fur. Two heterozygous short fur cats are crossed. If they have four kittens, what is the probability that they will have the following phenotypes? a) all short fur cats b) EITHER all short fur OR all long fur c) Three short fur and one long fur

Solution

2). To determine the genotype of an unknown plant with known phenotype, test cross is performed.

Test cross is a cross between dominant trait individual and recessive individual. It is done to determine the genotype (weather homozygous or heterozygous) of the individual in question mark. If the cross between the dominant trait and recessive individual results in both dominant and recessive phenotypes (in 1:1 ratio) in the offspring, the individual in question mark is “heterozygous.” If all the offspring are of dominant type, then the individual in question mark is “homozygous dominant.”

Assuming that the purple is dominant and is coded by the gene A, and the gene coding for the recessive phenotype for example white flowers is a; A is dominant over a.

Cross between the purple and white flower plants will have the progeny with the following genotypes.

Aa (heterozygous, purple)* aa (homozygous recessive), white ----> Aa (1/2, heterozygous, purple), aa (1/2, homozygous recessive, white). -à If this is the result of cross, the plant in question is heterozygous.

AA (homozygous, purple)* aa (homozygous recessive, white) ----> Aa (100%, heterozygous, purple), -à If this is the result of cross, the plant in question is homozygous.