Question

Familial hypercholesterolemia is a genetic disease that affects approximately one in 500 people worldwide. There is more than one genetic cause of the disease. In one type, heterozygous individuals have cholesterol levels >250 as children and often >300 as adults. However, homozygotes have cholesterol levels of >600 as children and can die of heart attacks in their 20s. These individuals entirely lack a functional LDL receptor. Which of the following would be the best description of the inheritance of this form of hypercholesterolemia? A. dominant epistatis B. codominant C. incompletely dominant D. complementary E. recessive epistatis

Iris and Raj just found out that they are going to have a baby. Iris’s maternal grandmother had Alper’s syndrome, which is inherited in an autosomal recessive manner. Iris’s parents are normal and you can assume her father is not a carrier. There is no history of this disorder in Raj’s family, so assume no one in his family is a carrier. What is the probability this baby will be a carrier for Alper’s syndrome? A. 0 B. 1/4 C. 1/2 D. 3/4 E. 2/3

Assume that a cross is made between AaBb and aabb plants and the offspring of the cross demonstrate the phenotypes associated with AB and ab in equal proportion. The results are consistent with which circumstances?

Answer 1

Answer 1) A) Dominant epistatis

if this disease occurs in 1 in every 500 individuals, it should firstly be noted that it is a common type of disease

the facts state that a heterozygous inheritment shows symptoms of the diseases but to a milder degree compared to the homoizygous inheritment, which means even if one allele is carrying the disease, it does not remain in the carrier state but actually gets expressed, therefore it shows that its a dominant trait.

Answer2) C 1/2

we know from the question that aper syndrome is a recessive trait therefore let the genotype of the Iris Grandmother be aa and grandfather be AA

Therefore Iris's mother becomes a carrier and her genotype is Aa. There is no specified history of Iris's father being a carrier/ diseased therefore his genotype will be AA

which means that there are 50% chances that Iris is a carrier. even if we consider that she is a carrier with genotype Aa, there is no evidence that her husband Raj has it since Raj's family has no history of the disease therefore Raj is AA

then the chances of the child being a carrier is AA X Aa = 50%

therefore the answer is 1/2

Answer 3) AaBb X aabb

AaBb produces AB Ab aB and ab

while aabb produces ab only

when we do a cross the phenotypic ratio will be 1:1:1:1 (AaBb , Aabb, aaBb, aabb) all different

thpis type of cross is called as a TEST CROSS

this is also known as a back cross where the F1 progeny is crossed with its recessive parent

i hope i was able to solve all your answers well :)