Biology

Human Genetics and Disorders

882 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 gene is a

  1. a type of body cell

  2. sleep inducing drug

  3. a kind of vitamin

  4. unit of heredity
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a polypeptide or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains.

Multiple choice

Which of the following are examples of autosomal dominant hereditary disorders?

P. Haemophilia Q. Phenylketonuria R. Achondroplasia S. Brochydatyly

Select the correct answer using codes given below:

  1. P and Q

  2. P and R

  3. Q and R

  4. Q and S

  5. R and S
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Achondroplasia is a form of short-limbed dwarfism. It is an autosomal dominant disorder. Brachydactyly is a shortening of the fingers and toes due to unusually short bones. It is an autosomal dominant disorder.

Multiple choice

Neonatal myasthenia occurs in about 12% of babies whose mother has myasthenia gravis. Neonatal myasthenia gravis is caused by

  1. an inherited genetic defect

  2. transplacental transfer of maternal IgG against the TSH receptor

  3. anti-idiotype to maternal IgG

  4. transplacental transfer of maternal IgG against the acetylcholine receptor

  5. maternal T-cells transferred across the placenta
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Transient neonatal autoimmune diseases are seen due to the transplacental transfer of maternal IgG autoantibodies in those diseases in which IgG is the effector component of the autoimmune response. The disease will be of the same type as seen in the mother because the autoantibodies will determine the target organ specificity. The neonatal disease resolves after a few weeks as the maternal IgG is catabolised.

Multiple choice

Which of the following statements regarding the autosomal recessive traits is wrong?

  1. The pattern of inheritance is horizontal.

  2. Closely related parents.

  3. The sex-linked genes are absent.

  4. In X-linked recessive traits mother is the carrier and father is healthy.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The abnormal genes located on X or Y chromosomes are called sex-linked genes. X-linked inheritance is more common and is expressed mostly as X-linked recessive traits

Multiple choice

The uniduchat syndrome is an example of

  1. deletion

  2. duplication

  3. Inversion

  4. translocation

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sometimes, a part of the chromosome is lost. This loss can be from one end or from chromosome parts between the ends. Accordingly, the former is known as terminal and the latter as interstitial deletion. Example:uniduchat syndrome: loss of half of the short arm of chromosome 5 in human.

Multiple choice

The high frequency of hip dysplasia, epilepsy and immune-system malfunctions in certain species of dog and are mainly consequence of

  1. Heterosis

  2. Ellis-van Creveld syndrome

  3. Consanguineous mating

  4. Random mating
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Consanguineous mating or inbreeding is an extreme form of positive assortative mating. It can result in a variety of homozygous recessive conditions showing up in phenotypes and a subsequent reduction in reproductive potential.

Multiple choice

High frequencies of genetically inherited diseases like thalessemia, haemophilia, etc in people who share a common ancestor is most likely the result of

  1. natural selection

  2. the founder effect

  3. genetic drift

  4. genomic selection
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This occurs when there is a small ancestral or founding population. The potentially numerous descendants of the founders often have similar genetic makeups. This explains why rare diseases are more frequent among descendants of people who had them.

Multiple choice

According to the recent studies, by the age of 35 years nearly 100% of people with Down syndrome develop

  1. Alzheimer syndrome

  2. Increased fertility

  3. Fragile-X syndrome

  4. Brett syndrome
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This progressive disease characterized by degeneration of brain cells resulting in severe memory loss usually occurs in old age for normal people, if it occurs at all. It is far more common among Down syndrome sufferers and it occurs at an earlier age.

Multiple choice

Brett syndrome is a rare form of mental retardation that can be more or less severe depending on the sex of the parent from whom it has been inherited. This unusual kind of inheritance pattern is known as

  1. a modifying gene inheritance

  2. genome imprinting

  3. incomplete penetrance

  4. pleiotropy
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When genes have a different effect depending on the gender of the parent from whom they were inherited, it is referred to as genome imprinting. Diabetes, psoriasis, and Prader-Willi syndrome are other examples of this phenomenon.

Multiple choice

Aditya's son is suffering from a chromosomal abnormality that causes males to have feminine body contours with large breasts, small penis, testes and prostate gland relatively little body hair; and sterility. This chromosomal abnormality may be

  1. Klinefelter syndrome

  2. XYY syndrome

  3. Triple-X syndrome

  4. XXXX syndrome
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The feminizing effects of Klinefelter syndrome can be diminished if boys are treated regularly with testosterone injections from the age of puberty on. As a result of this treatment, most become sufficiently ordinary in appearance to live in society without notice.

Multiple choice

Why is a mutation in the p53 gene so important?

  1. Cell division is stopped.

  2. Cells grow in size and multiple nuclei originates.

  3. The ras gene is inhibited.

  4. Cell division is uncontrolled.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When the p53 gene mutates, cell division is no longer regulated.

Multiple choice

Lactase deficiency is

  1. equally common throughout the world

  2. at its highest frequency in Europe

  3. at its lowest frequency in Asia

  4. none of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Lactase deficiency has a non-random distribution. Generally, it is the least common among Europeans. Asians and Native Americans have very high frequencies. In Africa, there are regions of extremely high frequency and others of low frequency.