Biology

Human Genetics and Disorders

844 Questions

Human Genetics and Disorders covers the inheritance patterns, genetic mutations, and molecular basis of hereditary diseases. Topics include sex-linked traits, cancer genetics, and metabolic disorders. This section tests knowledge critical for biology exams and general science papers.

Genetic mutationsInherited disordersCancer geneticsGenetic testingMendelian inheritance

Human Genetics and Disorders Questions

Multiple choice

A doctor told a couple that their son is suffering from a disease resulting from the deletions in the T-cell CD154 (CD40L) gene. Which of the following diseases must the doctor be referring to?

  1. Hyper-IgM syndrome

  2. Congenital X-linked agammaglobulinemia

  3. IgA deficiency

  4. Wiskott-Aldrich syndrome

  5. Deficiency in cytotoxic T-cell activity
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lack of CD154 (CD40L) prevents signalling to the B-cell CD40 to bring about Ig class-switching away from IgM.

Multiple choice

Thymidine dimers are usually the consequence of

  1. ultraviolet light exposure

  2. radiation exposure

  3. chemical exposure

  4. advanced paternal age

  5. chemotherapy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Thymidine dimers are a pair of abnormally chemically-bonded adjacent thymine bases in DNA, resulting from damage by ultraviolet irradiation.

Multiple choice

Which of the following are examples of autosomal recessive disorders?

  1. Thalassemia
  2. Cystic fibrosis
  3. Huntington's disease
  4. Haemophilia A

  1. 1 and 2

  2. 1 and 3

  3. 1 and 4

  4. 2 and 3

  5. 2 and 4
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is the correct answer. Thalassemia is a form of inherited autosomal recessive blood disorder characterised by abnormal formation of haemoglobin. Cystic fibrosis is an autosomal recessive genetic disorder characterised by the buildup of thick, sticky mucus that can damage many of the body's organs.

Multiple choice

Which of the following are examples of pleiotropy?

  1. Phenylketonuria
  2. Haemophilia
  3. Albinism
  4. Colour blindness
  5. Sickle-cell anaemia

  1. 1, 2 and 3

  2. 1, 3 and 5

  3. 2, 3 and 4

  4. 2, 4 and 5

  5. 3, 4 and 5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Pleiotropy occurs when one gene influences multiple, seemingly unrelated phenotypic traits. Consequently, a mutation in a pleiotropic gene may have an effect on some or all traits simultaneously. Well known examples of pleiotropy include phenylketonuria, albinism and sickle-cell anaemia.

Multiple choice

Obesity is considered to be the result of the combination of deletions, SNPs and gene mutations. Which among the following does not characterise monogenic obesity?

  1. It occurs due to the congenital leptin deficiency.

  2. The common monogenic obesity disorder was represented by excess of MC4R.

  3. The phenotype is directly and strongly related to the genotype.

  4. In leptin melanocortin pathway, leptin crosses the blood brain barrier and triggers the neurons present in the hypothalamus to generate peptides.

  5. The receptor gene mutations might be one of the reasons for severe obesity.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The mutation in the melanocortin-4 receptor protein (MC4R) which is a component of leptin-melanocortin pathway was detected to be related to obesity. The common monogenic obesity disorder was represented by MC4R deficiency. The obesity was accounted due to homozygous and heterozygous mutations in MC4R.

Multiple choice

The genetic abnormality called mongolism is an example of

  1. Allosomal abnormality

  2. Autosomal abnormality

  3. Y chromosomal abnormality

  4. X chromosomal abnormality

  5. Sex chromosomal abnormality
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The genetic abnormality called mongolism is an example of autosomal abnormality.