MCQs on Mendelian Disorders in Humans

The genetic disorders caused at a single genetic locus are referred to as Mendelian disorders. It is a type of genetic disorder in humans primarily caused either due to abnormalities in the genome or changes in a single genome. The condition is found to be present since birth. These disorders may or may not be inherited.

1. A type of autosomal recessive genetic disorder is

(a) Hemophilia

(b) Skeletal dysplasia

(c) Sickle cell anemia

(d) None of the above

Answer: (c)

2. Which of these is known as Royal disease?

(a) Colour blindness

(b) Haemophilia

(c) Sickle cell anaemia

(d) Alzheimer’s disease

Answer: (b)

3. The important example of point mutation is found in a disease known as

(a) Down’s syndrome

(b) Night blindness

(c) Thalassemia

(d) Sickle cell anemia

Answer: (d)

4. If the father in a family has a disease while the mother is normal, the daughters only are inherited by this disease and not the sons. Name this type of disease

(a) Autosomal recessive

(b) Autosomal dominant

(c) Sex linked recessive

(d) Sex linked dominant

Answer: (d)

5. Which of these phenotypes and genotypes in a man may be the correct result of aneuploidy in sex chromosomes?

(a) 22 pairs + XXXY females

(b) 22 pairs + XXY females

(c) 22 pairs + XY females

(d) 22 pairs + Y females

Answer: (b)

6. What will the condition of the progeny be if the father is normal while the mother has one gene for haemophilia and one gene for colour blindness on one of the X chromosomes

(a) All sons and daughters are haemophilic and colour blind

(b) Haemophilic and colour blind daughters

(c) 50% haemophilic colour blind sons and 50% colour blind daughters

(d) 50% haemophilic and colour blind sons and 50% normal sons

Answer: (d)

7. Cystic fibrosis is an autosomal recessive genetic disorder. If one parent of a child is a carrier possessing one copy of the faulty cystic fibrosis gene (Cc), other parent is not a carrier(genotype = CC). What are the chances that the child would have the disease?

(a) 100%

(b) 50%

(c) 25%

(d) 0%

Answer: (d)

8. Alpha 1 anti-trypsin deficiency is an autosomal recessive genetic disorder. What is the chance of any of the offspring to not express the disease phenotype if both parents are genotype (Aa)?

(a) 100

(b) 75

(c) 50

(d) 25

Answer: (b)

9. Which of the following is a trait of X-linked recessive

(a) Haemophilia

(b) Albinism

(c) Huntington’s disease

(d) None of these

Answer: (a)

10. The mode of inheritance for the trait – Fragile X syndrome is

(a) X linked dominant

(b) X linked recessive

(c) Autosomal dominant

(d) Autosomal recessive

Answer: (a)

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