In the Datura plant, purple flower color is controlled by a dominate allele P. W
ID: 181809 • Letter: I
Question
In the Datura plant, purple flower color is controlled by a dominate allele P. White flowers are found in plants homozygous for the recessive allele p. Suppose that a purple-flowered Datura plant with an unknown genotype is self-fertilized and that its progeny are 28 purple-flowered plants and 10 white-flowered plants. What is the genotype of the original purple plant? What is the probability that a randomly chosen purple F1 plants is a heterozygote? A gene that controls colorblindness is on the X chromosome. The colorblind allele is recessive to the normal allele. A woman who Is a carrier for colorblindness has a child with a phenotypically normal man, what is the chance that they will have a non-colorblind girl? A nondisjunction event led the couple to have a little boy with Klienfelter syndrome (XXY) and colorblindness. In which parent, did nondisjunction happen?Explanation / Answer
2. Since purple coloured flower may have eigher Pp or PP genotype and the ratio of the progeny are nearly 3:1, so on self fertilization, genotype PP will give only purple colour to all the plants.
So, the genotype of the purple coloured flower should be Pp.
(b) :- Since the ratio for the heterozygous and homozygous is 1:2:1, so the probability of the flower having heterozygous plant is 50%.
3. Since the man is phenotypically normal to the colourblindness, so there is 100% chance that they will have a non colourblind girl because no any gene for the colourblindness from the father will pass to the baby girl and mother is only a carrier for the colourblindness and it is recessive.
(b) :- Since the baby boy also have colourblindness along with the Kleinfelter syndrome due to the non dysjunction, this non dysjunction must be occured in the mother's gene because only mother is the carrier for the colourblindness.