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Genetics and Evolution

Description: This test will help the students to prepare themselves more better as it covers many important topics.
Number of Questions: 15
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Tags: Inheritance Gene Expression and Regulation Regulation of Gene Expression Mutation Cytoplasmic Inheritance Genetics and Evolution Inheritance Pattern of Haemophilia and Blood Groups in Human Beings
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The doctor told his patient that he is suffering from a metabolic disorder caused by a mutation in the DHCR7 gene on chromosome 11. Which among the following disorders is the doctor referring to?

  1. Smith-Lemli-Opitz syndrome

  2. Phenylketonuria

  3. Neurofibromatosis type 1

  4. Sickle cell anemia

  5. Severe Combined Immunodeficiency


Correct Option: A
Explanation:

SLOS Chromosome SLOS is a metabolic disorder caused by a mutation in the DHCR7 (7-dehydrocholesterol reductase) gene on chromosome 11. This gene codes for an enzyme that is involved in the production of cholesterol. People who have SLOS are unable to make enough cholesterol to support normal growth and development.

We are all unique. Every one of us has a unique combination of traits. Which among the following variable traits are influenced by a combination of genes and environmental factors?

  1. Earlobe attachment

  2. Tongue rolling

  3. Dimples

  4. Handedness

  5. Freckles


Correct Option: B
Explanation:

Some people can curl up the sides of their tongue to form a tube shape. Tongue rolling is controlled by a single gene. However, people can learn to roll their tongue as they get older, suggesting that environmental factors also influences the trait.

Which of the following cellular proteins is affected directly by the treatment with everolimus?

  1. Hamartin

  2. mTOR

  3. Tuberin

  4. Rheb

  5. Akt


Correct Option: B
Explanation:

Everolimus is an inhibitor of mTOR, substituting for the lack of inhibition due to mutation of TSC1 or TSC2.

After examining a 14 years old child, doctors told the parents that their child is suffering from a chromosomal abnormality which is usually caused by nondisjunction of chromosomes. Which among the following chromosomal abnormalities, the child must be suffering from?

  1. Klinefelters syndrome

  2. Cri-du-chat

  3. Downs syndrome

  4. Williams syndrome

  5. Turners syndrome


Correct Option: A
Explanation:

Klinefelters syndrome is usually caused by nondisjunction of chromosomes. Nondisjunction happens when a pair of sex chromosomes fails to separate during egg (or sperm) formation. When an egg (or sperm) with an extra X chromosomes joins with a normal sperm (or egg), the resulting embryo will end up with three sex chromosomes (XXY) instead of the normal two (XX or XY). As the baby develops, the extra chromosome is then copied in every cell.

A man with a tumor carrying a translocation of chromosomes 9 and 22, is suffering from which of the following?

  1. Retinoblastoma

  2. Li–Fraumeni syndrome

  3. Soft tissue sarcoma

  4. Chronic myelogenous leukemia

  5. Hereditary nonpolyposis colon cancer


Correct Option: D
Explanation:

Chronic myelogenous leukemia is an uncommon type of cancer of the blood cells. The t(9;22) describes the Philadelphia chromosome, in which the bcr gene on chromosome 22 is juxtaposed to abl on chromosome 9.

The actual skin color of different humans populations is affected the pigment melanin. Which among the following genes regulates calcium in melanocytes?

  1. TYR gene

  2. SLC45A2 gene

  3. SLC24A5

  4. KITLG gene

  5. MC1R gene


Correct Option: C
Explanation:

This gene regulates calcium in melanocytes and is important in the process of melanogenesis.

Which of the following statements regarding the ABO blood types is incorrect?

  1. Antibodies to alien antigens in the ABO group lies in plasma.

  2. Individuals having type A blood will have the A antigen on the surface of their red cells.

  3. The environment potentially can determine which blood types in a population will be passed on more frequently to the next generation.

  4. Individuals having O blood group cannot receive A, B and AB blood.

  5. ABO blood type antigens are found on the surface of red blood cells.


Correct Option: E
Explanation:

ABO blood type antigens are not only found on the surface of red cells. They are also normally secreted in their body fluids, including saliva, tears and urine.

Upon chromosomal analysis, it was confirmed that Anuja's youngest son is suffering from a genetic disorder in which the defective gene is present on chromosome 7. The boy must be suffering from ________.

  1. single gene disorder

  2. dominant disorder

  3. mitochondrial disorder

  4. chromosome disorder

  5. multifactorial genetic disorder


Correct Option: A
Explanation:

This type of human genetic disorder occurs when a change happens in part of a gene's DNA sequence. Genes make proteins, and a mutation in the gene will result in the protein not being able to function properly. Cystic fibrosis is an example of a single-gene disorder. Patients with the condition have a defective gene on chromosome 7 called CFTR.

Which among the following is an ostensible transforming gene of avian sarcoma virus 17?

  1. Bcl-2 gene

  2. BCL3 gene

  3. c-jun gene

  4. TBX21 gene

  5. ZBTB16 gene


Correct Option: C
Explanation:

This gene is the putative transforming gene of avian sarcoma virus 17. It encodes a protein which interacts directly with specific target DNA sequences to regulate gene expression.

The phenomenon of anticipation is associated with which of the following types of mutation?

  1. Deletion

  2. Genomic imprinting

  3. Stop-Codon

  4. Triplet repeat expansion

  5. Missense


Correct Option: D
Explanation:

Anticipation occurs in association with triplet repeat expansion mutations. The larger the expansion is, the earlier the onset and the more instable the mutation will be. Larger expansions therefore, present earlier in life, and are prone to further expansion in the next generation.

A dominantly inherited trait affects a 12 year old boy and his grandmother, but not the parents. This best illustrates which of the following principles?

  1. Variable expressivity

  2. New mutation

  3. Somatic mosaicism

  4. Nonpenetrance

  5. Germline mosaicism


Correct Option: D
Explanation:

Non-penetrance means that a person has inherited the genetic change, but that it does not manifest the associated phenotype.

The biologist involved with immunochemistry is ________.

  1. John Gurdon

  2. George Emil Palade

  3. W. Boyer

  4. Linus Pauling

  5. Oswald Avery


Correct Option: E
Explanation:

Oswald Avery was one of the pioneers of the scientific discipline of immunochemistry.

Which among the following traits is a result of natural selection?

  1. Eye color

  2. Widow's peak

  3. Hitchhiker's thumb

  4. Tongue rolling

  5. Skin color


Correct Option: E
Explanation:

Human skin color ranges in variety from the darkest brown to the lightest pinkish-white hues. Human skin pigmentation is the result of natural selection. Skin pigmentation in human beings evolved primarily to regulate the amount of ultraviolet radiation penetrating the skin, controlling its biochemical effects.

Alpha satellite DNA is a repetitive sequence. It is preferentially localized at ________.  

  1. telomeres

  2. stalks of acrocentric chromosomes

  3. dark G-bands

  4. centromeres

  5. light G-bands


Correct Option: D
Explanation:

Alpha satellite DNA is a repetitive sequence known to be a major DNA component of centromeres in primates (order Primates).

Which of the following genetic conditions arises by unequal crossing over between X and Y chromosomes during meiosis in the biological father of an individual?

  1. 48, XXXX

  2. 49, XXXXX

  3. 47, XYY

  4. 48, XXYY

  5. XX male syndrome


Correct Option: E
Explanation:

XX male syndrome is a rare sex chromosomal disorder. Usually it is caused by unequal crossing over between X and Y chromosomes during meiosis in the father, which results in the X chromosome containing the normally-male SRY gene.

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