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

The most significant limitation of molecular analysis of the HFE gene for screening for hemochromatosis in individuals of northern European descent is

  1. non-penetrance

  2. allelic heterogeneity

  3. locus heterogeneity

  4. variable expression
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A significant proportion of individuals who are homozygous for an HFE mutation will not develop signs or symptoms of iron overload. There are only two HFE mutations that account for most affected individuals, and HFE mutation accounts for the majority of cases of hemochromatosis in individuals of northern European descent.

Multiple choice

Which of the following is a major limitation of DNA-based carrier screening in cystic fibrosis?

  1. Laboratory errors in mutation analysis

  2. Nonpenetrance of many CFTR mutations

  3. Germline mosaicism

  4. Incomplete ascertainment of mutations
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The current approach to carrier detection involves testing of a limited panel of mutations, which results in failure to detect some of the rarer CFTR mutations. Negative carrier testing does not mean that an individual is not a carrier, though negative testing reduce an individual's risk of being a carrier.

Multiple choice

Select the CORRECT statement regarding the worldwide frequency distribution of the different ABO blood types.

  1. It is much composite, having both clinal and discontinuous patterns.

  2. It follows latitude lines suggesting that climate plays a significant role for determining the above trait.

  3. It is predictable, with each continent having its own unique type among the inherent populations.

  4. The people of each continent have their own distinct blood type.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This suggests that natural selection, migrations, genetic drift, the founder principle, and non-random mating were all potentially important factors in our evolutionary history.

Multiple choice

Which of the following statements is TRUE?

  1. The worldwide distribution patterns for the ABO blood system signifies the typological model of human variation.

  2. Human blood can be unambiguously typed, i.e. there is no degree of difference.

  3. Mapping the distribution of blood types has proven to be insignificant tool for studying the nature of human variation.

  4. Human blood cannot be unambiguously typed.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Unlike such traits as skin colour and hair texture, blood comes in specific, non-blending types. There are no shades of difference--you cannot be halfway between type O and A.

Multiple choice

Which of the following statements is CORRECT about the worldwide frequency distribution of blood types B and O?

  1. They very nicely overlap indicating that whatever factors have been selecting for type B have also been at work selecting for type O.

  2. Where type O is relatively high in frequency, type B is ultimately relatively low.

  3. They both are very alike to the distribution pattern of skin colour indicating that the same factors have been favoured for blood types and skin pigmentation.

  4. Where type B is relatively high in frequency, type O is relatively low.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Type O is most common among Native Americans. However, type B is extremely low in Americans.

Multiple choice

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

  1. modifying gene

  2. genome imprinting

  3. incomplete penetrance

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

When genes have different effects 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

Which of the following statements is TRUE?

  1. With the exception of monozygotic twins, each of us is unique in terms of the combination of tens of thousands of genetically inherited peculiar qualities that we possess.

  2. Blackish skin is found only among Africans and people whose ancestors came from Africa in recent centuries.

  3. Non-African people with black skin colour posses a close common ancestry with Africans.

  4. The personal physical qualities of an individual are determined by the genetic inheritance.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Except for monozygotic (identical) twins, it is highly likely that every one of us is genetically different from every other human whoever lived.

Multiple choice

A 15 year old boy develops a disorder, which is present in his father and no one else in the family is known to be affected. Which of the following modes of inheritance is least likely?

  1. Autosomal recessive

  2. Autosomal dominant

  3. X-linked recessive

  4. Sex-linked dominant
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An X-linked trait does not display male to male transmission. Any of the others are possible, including autosomal recessive, if the mother is also heterozygous (pseudo-dominant transmission).