Evolution & Genetics

Description: This test contains certain questfor medical aspirants.ions based on evolution & genetics which are highly helpful
Number of Questions: 25
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Tags: Genes heredity Mendel haemophlilia primates catastrophism linkage variations etc Gene Expression and Regulation Regulation of Gene Expression Inheritance Pattern of Haemophilia and Blood Groups in Human Beings Genetics and Evolution Chromosomal Theory of Inheritance
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In an experiment, it was discovered that there was a single human gene responsible for all of the various forms of physical destruction associated with diabetes, it would be referred as

  1. a modifying gene

  2. pleiotropy

  3. a regulator gene

  4. hox gene

Correct Option: B

Pleiotropy is a genetic inheritance pattern in which a single gene causes or affects an entire series of traits.

A regulator gene can

  1. alters the expression of another gene

  2. alters the sex of an adult human

  3. initiates the expression of another gene

  4. not code for repressor proteins

Correct Option: C

Regulator genes control the timing and duration of production of a variety of substances such as proteins in our bodies.

Incompletely penetrant genes are expressed in

  1. phenotypes

  2. genotypes

  3. heterozygous individuals

  4. homozygous individuals

Correct Option: A

The example of an incompletely penetrant genetic inheritance is multiple sclerosis. It apparently develops when an individual who carries the gene or genes for this disease is attacked by a virus that causes a flu-like illness.

Which among the following does not characterise polygenic traits?

  1. These are controlled by more than a single pair of alleles.

  2. These are responsible for a number of traits in the phenotype.

  3. These are found in either men or women, but not in both.

  4. The phenotype of an individual depends on alleles in multiple genes.

Correct Option: A

Polygenic traits are determined by multiple pairs of alleles. Simple Mendelian rules of dominance do not readily apply. Human stature is an example. It results from all of the genes that determine the size of all body parts from head to foot.

If a single pair of alleles determines the number of fingers for an animal species and homozygous dominant individuals have 8 fingers, heterozygous ones have 7, and homozygous recessive ones have 6, the inheritance pattern would be referred to as

  1. genome imprinting

  2. intermediate expression

  3. pleiotropy

  4. reduced penetrance

Correct Option: B

This hypothetical example would be an example of the intermediate expression of a trait. Apparently, this is rare. For most genes, it is expected that individuals with heterozygous genotypes will have phenotypes like homozygous dominant individuals.

Few individuals are AB blood types of the ABO blood system. They posses all the features of both type A and type B blood but they are not a blend of them. This is due to the

  1. codominance

  2. dominance

  3. blending

  4. pleiotropy

Correct Option: A

Codominant traits are the ones in which both alleles are expressed when the phenotype is heterozygous. In the case of the ABO blood type system, A and B are codominant. They are also completely dominant over O.

The genes for a trait are inherited by son & daughter of a couple but only show up in the phenotype of daughter, they are referred to as

  1. sex-controlled genes

  2. codominant genes

  3. sex-limited genes

  4. sex-linked genes

Correct Option: C

Only one gender actually has sex-limited genes expressed in the phenotype, while both inherit them. The typical heavy male facial beard is an example of a trait whose inheritance follows this pattern.

Angelman syndrome is a severe form of mental retardation which depends upon the gender of the parent from whom they are inherited. This unusual kind of inheritance pattern is known as

  1. modifying gene

  2. genome imprinting

  3. incomplete penetrant

  4. intermediate expression

Correct Option: B

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

If there was a gene for beauty in the body but the effect of this gene is altered by the inheritance of another gene, the latter gene is referred as

  1. sex-controlled gene

  2. modifying gene

  3. structural gene

  4. split gene

Correct Option: B

Modifying genes alter the effect of companion genes in the phenotype of an individual. A real life example is a gene that modifies the effect of a dominant cataract allele.

What would a gene be called if it is inherited by both the parents but expressed differently in the phenotype of son and daughter?

  1. Unstable

  2. Sex-controlled

  3. Recessive

  4. Operator

Correct Option: B

An example of a sex-controlled genetic trait is gout. While both men and women can get it, men generally have more severe symptoms.

The monozygotic twins may not have identical phenotypes because

  1. their genotypes are different

  2. their phenotypes are effected by environment

  3. their phenotypes are independent of their genotypes

  4. they develop from different zygotes

Correct Option: B

While monozygotic twins are identical in genetic makeup, but the individuals after conception and birth can alter their phenotypes.

The interaction between different genes is termed as

  1. multiple-allelism

  2. mutation

  3. syndrome

  4. epistasis

Correct Option: D

It is described as the interaction between genes. It can be contrasted with dominance, which is an interaction between alleles at the same gene locus.

Which of the following can be regarded as an exception to Mendel's concept that genes are passed on, unchanged, from one generation to other?

  1. Codominance

  2. Multiple-alleles

  3. Stuttering alleles

  4. Incomplete dominance

Correct Option: C

Stuttering or unstable alleles structurally change from generation to generation. Segments of these rare genes are doubled with each generation, resulting in an intensification of a trait. One form of muscular dystrophy apparently can follow this pattern.

Pick out the true statement regarding the karyotype analysis.

  1. It is frequently done on the cells of foetus because it cannot detect the most genetic disorders.

  2. It is now an important medical tool used in forecasting the likelihood that the foetus will be normal.

  3. It is not used, now a days, because human pregnancy has only a small risk of birth defects.

  4. It is the number and appearance of chromosomes in the nucleus of a prokaryotic cell.

Correct Option: B

When the family history or age of the mother indicates a high risk of gross chromosomal abnormalities, embryonic or fetal tissue samples are often collected and cultured so that a karyotype of the chromosomes can be analyzed.

The nature of an unborn child having severe genetic defect such as mental retardation, can frequently be detected by sampling

  1. mother's uterus cells

  2. foetal cells

  3. father's blood cells

  4. cells from zygote

Correct Option: B

A karyotype of the embryonic or foetal cells extracted from within a mother's uterus may show chromosome irregularities that are associated with specific kinds of major genetic problems.

In a family, having a history of genetic disorders, knowing the sex of a foetus can be important because

  1. sons will be more prone to autosomal defects

  2. daughters will be more prone to autosomal defects

  3. both son & daughter will be equally affected

  4. There will be more chances that sons will bear X-linked traits expressed in their phenotype.

Correct Option: D

There is a far greater probability of males expressing recessive alleles in their phenotypes if they are carried on X chromosomes. For females to have such traits, they would have to inherit the recessive allele for them on both of their X chromosomes.

In medical science, amniocentesis is an advanced technique which involves the sampling of

  1. amniotic fluid

  2. amnion

  3. placenta

  4. uterus

Correct Option: A

A foetus and the surrounding amniotic fluid are within the amniotic sac. Amniotic fluid mostly contains fetal urine but also has millions of fetal skin cells that can be cultured to produce a karyotype. As a result, this is what actually sampled.

The advanced medical techniques like amniocentesis, chorionic villi sampling, and alpha-fetoprotein sampling are mainly done for determining

  1. the date of birth of child

  2. the abnormalities in baby

  3. any genetic disorder of mother

  4. the date of conceiving

Correct Option: B

These are standard diagnostic tools to determine whether or not an unborn child is at risk for a small range of very serious genetic disorders.

An individual only has one X chromosome and no Y chromosome in his somatic cells. Such a condition is

  1. Metafemale

  2. Turner's syndrome

  3. Klinefelter's syndrome

  4. Down's syndrome

Correct Option: B

People with Turner syndrome are females who inherit only one X chromosome.Their genotype is usually written X0.

Karyotyping can be done from

  1. any cell in the body

  2. only sex cells

  3. only foetal cells

  4. only zygotic cells

Correct Option: A

Cells in blood, hair, finger nails, and any other tissues in our body can be cultured to create a karyotype of the chromosomes. Since all of your somatic cells will have the same chromosomes, it generally doesn't matter which ones are used.

Which among the following is a characteristic of individuals suffering from Down syndrome?

  1. They are only mildly mentally retarded.

  2. They often have other related medical problems.

  3. They generally have a longer life span than average.

  4. They generally suffers from obesity.

Correct Option: B

They have a much greater chance than average of having epilepsy, hypothyroidism, crossed eyes, cataracts, heart defects, hernias, a marked susceptibility to respiratory infections such as pneumonia, and childhood leukemia.

A female is suffering from unusually short height (average 4'7), webbed neck, & lacks all feminine secondary sexual characteristics. This chromosomal abnormality is caused by

  1. Triple-X syndrome

  2. Turner's syndrome

  3. XYY syndrome

  4. Klinefelter's syndrome

Correct Option: B

Women with Turner syndrome are essentially postmenopausal from early childhood and are sterile because their ovaries do not develop normally and they do not ovulate.

Pick out the true statements regarding the sex chromosome abnormalities in humans.

  1. These generally have mild effects, which are rarely fatal.

  2. These are not gender specific.

  3. These cannot be diagnosed before birth.

  4. These are more common than autosomal abnormalities.

Correct Option: A

Because sex chromosome abnormalities rarely result in an early death and their symptoms are not often severe, comparatively large number of people with these abnormalities survive to old age.

Which among the following chromosomal abnormalities causes male to have feminine body contours with bigger breasts; small penis and prostate gland with relatively little body hair and impotency?

  1. Klinefelter's syndrome

  2. XYY syndrome

  3. Richard Speck Syndrome

  4. Achard syndrome

Correct Option: A

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

Down syndrome involves an abnormality of chromosome pair number

  1. 3

  2. 11

  3. 21

  4. 23

Correct Option: C

In most Down syndrome cases, there is an extra chromosome 21 (i.e. trisomy-21). More rarely, there is a structural modification in one or both of the chromosomes in this homologous pair.

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