In a family, father and son express a sex-linked recessive trait. The mother is phenotypically normal. What is the probability that she might be a carrier for the trait?
1. | 0 | 2. | 0.25 |
3. | 0.5 | 4. | 1.0 |
In Drosophila melanogaster cinnabar eye is a sex-linked recessive trait. A female fly having cinnabar eyes is crossed with a wild-type male. The percentage of the male progeny of this cross with cinnabar eyes is expected to be:
1. | 0% | 2. | 25% |
3. | 50% | 4. | 100% |
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 chance that this child would be colour–blind?
1. | 100% | 2. | zero percent |
3. | 25% | 4. | 50% |
If a father and son are both affected by red-green colour blindness, then what can be said definitely?
I. | The son has received the trait from the father. |
II. | The mother of the affected son has to be affected by red-green colour blindness. |
III. | Any sister of the affected son can never be affected by red-green colour blindness. |
1. | I and II only | 2. | I and III only |
3. | II and III only | 4. | None |
If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is:
1. | Autosomal dominant | 2. | Autosomal recessive |
3. | Sex-linked dominant | 4. | Sex-linked recessive |