A colour blind man marries a woman with normal sight who has no history of colour blindness in her family. What is the probability of their grandson being colour blind?
0.5
1
Nil
Nil
C.
Nil
When a colour blind (XCY) marries to a woman with normal sight (XX) who has no family history of colour blindness, all of their sons will be normal pure and all of their daughters will be carriers as shown below:
So in the next generation, the children of all of their son will be normal in all conditions(except the case in which the wife involved is not carrier neither colour blind). For carrier daughters.
(i) If they many to a normal man 50% of their grandsons will become colour blind as
(ii) If carrier daughter marries to a colour blind man 50% of their grandson will be colour blind along with 50% of the grand daughter while rest 50% of the grand daughters will be carriers as
So in both the above cases, the result shows 50% of grand sons will be colour blind which in terms of over all progress (son + daughter) comes as 25% thus confirming the probability as 0.25.
The incorrect statement with regard to haemophilia is
It is a sex - linked disease
It is a recessive disease
It is dominant disease
It is dominant disease
If both parents are carriers for thalassemia, which is an autosomal recessive disorder, what are the chances of pregnancy resulting in an affected child?
No Chance
50%
25%
25%
Which enzyme/s will be produced in cell in which there is a non-sense mutation in the lac Y gene?
beta - galactosidase
Lactose permease
Transacetylase
A gene showing codominance has:
One allele dominant on the other
alleles tightly linked on the same chromosome
alleles that are recessive to each other
alleles that are recessive to each other
In the following human pedigree, the filled symbols represent the affected individuals. Identify the type of given pedigree. 
Autosomal dominant
X-linked recessive
Autosomal recessive
Autosomal recessive
In his classic experiments on pea plants, Mendel did not use
Seed colour
Pod length
Seed shape
Seed shape
Fruit colour in squash is an example of
recessive epistasis
dominant epistasis
complementary genes
complementary genes
A normal-visioned man whose father was colour-blind, marries a woman whose father was also colour-blind. They have their first child as a daughter. What are the chances that this child would be colour-blind?
100%
0%
25%
25%
