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 pleiotropy genetics zoology

A pleiotropic gene in humans is

  1. Marfan's syndrome

  2. Colour blindness

  3. Eye colour

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

Mutations in the human gene for fibrillin-1 (FBN1) in the Marfan syndrome and related disorders. Mutations in FBN1 produce Marfan syndrome, a pleiotropic autosomal dominant connective tissue disorder with prominent manifestations in the skeleton, eye and cardiovascular system.

So, the correct information is 'Marfan's syndrome.'

Multiple choice pleiotropy genetics zoology

The gene disorder phenyl ketonuria is an example for ___________.

  1. Polygenic inheritance

  2. Pleiotropy

  3. Multiple allelism

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

Phenylketonuria is a recessive autosomal disorder related to phenylalanine metabolism. It is controlled by a single gene having  multiple phenotypes. So it is a pleiotrophy. This disorder is due to the absence of a liver enzyme phenylalanine hydroxylase. Due to the lack of this enzyme, phenylalanine follows another pathway and gets converted into phenyl pyruvic acid. This phenyl pyruvic acid upon accumulation in joints causes arthritis. If it hits the brain, it causes mental  retardation known as phenyl pyruvic idiocy.

So, the correct option is ‘Pleiotrophy’

Multiple choice pleiotropy genetics zoology

In Drosophila gene for white eye colour is also responsible for depigmentation of body parts. It is an example of

  1. Oncogene

  2. Epistatic gene

  3. Hypostatic gene

  4. Pleiotropic gene

  5. Sex-linked
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The ability of a gene to have a multiple phenotypic effects is known as pleiotrophy and the gene is called Pleiotropic gene and the inheritance is called Pleiotropic inheritance. In Drosophila, a gene is responsible in controlling the colour of the eye and depigmentation of body parts. It is a pleiotropic gene.

So, the correct option is ‘Pleiotropic gene’.

Multiple choice pleiotropy genetics zoology

Which of the following disorders is not caused by pleiotropic alleles _______________.

  1. Sickle cell anemia

  2. Cystic fibrosis

  3. Phenylketonuria

  4. Erythroblastosis foetalis.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A.Sickel cell anaemia – Pleiotropic alleles

B.Cystic fibrosis – Pleiotropic alleles

C.Phenylketonuria – it is autosomal recessive disorder.

D.Erythroblastosis foetalis – It is also called hemolytic disease of the newborn, type of anemia in which the red blood cells (erythrocytes) of a foetus are destroyed in a maternal immune reaction resulting from a blood group incompatibility between the foetus and its mother.

So, the correct option is ‘Erythroblastosis foetalis’.

Multiple choice pleiotropy genetics zoology

Pleiotropic effect is found in

  1. Human skin colour

  2. Night blindness

  3. Haemophilia

  4. Sickle cell anaemia
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The ability of a gene to have a multiple phenotypic effects is known as pleiotrophy and the gene is called Pleiotropic gene and the inheritance is called Pleiotropic inheritance.

eg:Sickel cell anaemia

So, the correct option is ‘sickle cell anaemia’.

Multiple choice zoology important and common human diseases diseases caused by changes in lifestyle diseases and toxic substance non-infectious diseases

Alteration in which genes leads to cancer

  1. Proto-oncogenes

  2. Tumor suppressor gene

  3. Tumor virus gene

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Genes are found in the DNA of every cell of the human body. The functions of the cell, its growth pattern, divisions and life are all determined and control by the genes. Cancers in the human body are the result of mutations or changes in one or more genes in a cell leading to an abnormal protein or no protein at all. An abnormal protein in the cells causes them  to multiply uncontrollably and become cancerous. Any alteration in the tumour suppressor gene may result in cancer. 

The region of the viral genome (DNA in DNA tumour viruses or RNA in RNA-tumour viruses) that can cause a tumour is called an oncogene. These mutations are generally acquired mutations. However, alterations or mutations of cell proliferation genes or oncogenes lead to cancer.
So, the correct answer is option D. 

Multiple choice zoology important and common human diseases allergy and autoimmune diseases allergy non infectious diseases

Which of the following term is used as inherited tendency to develop allergic diseases?

  1. Atopy

  2. Epitope

  3. Virulence

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Atopy is the condition which has been developed due to exposure to allergens in which the person is susceptible to allergic reactions. This is an inherited syndrome. The person is more likely to develop the allergic reactions like rash, rhinitis, asthma, etc when encountered with the allergen. 

Thus, the correct answer is option A. 

Multiple choice zoology selection and evolution extinction extinctions environmental science

Choose the correct answers from the alternatives given.
The continued occurrence of sickle-cell disease in parts of Africa with malaria is due to

  1. Disruptive selection

  2. Continual mutation

  3. Fitness of the heterozygote

  4. Gene flow between populations
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sickle cell anemia is an inherited blood disease where red blood cells show an abnormal crescent (or sickle) shape. It is an autosomal recessive disease in which one gene of allele codes for a normal protein and the other one codes for defective hemoglobin (sickle-celled). 


Heterozygous individuals ie., carrying just one copy of the sickle mutation (inherited from either the father or mother), do not develop sickle cell anemia. However, such individuals are protected against malaria. This defective hemoglobin cause sickling of RBC in which malarial parasite cannot survive. This explains the high prevalence of this mutation in parts of Africa, where malaria is endemic.

So the correct answer is "Fitness of the heterozygote"

Multiple choice biology variation variation and its type natural selection introduction to genetics

Which of the following is not heritable?

  1. Point mutation

  2. Chromosomal mutation

  3. Somatic mutation

  4. Gene mutation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • Point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a sequence of DNA or RNA. Each triplet codon corresponds to an amino acid when translated to protein. When one of these codons is changed by a point mutation, the corresponding amino acid of the protein is changed.
  • Chromosomal mutation is presence or absence of one or more set of chromosomes in a cell or a structural abnormality in the normal set of chromosomes.
  • Somatic mutation is the occurrence of a mutation in the somatic cells (cells other than sperm and egg) of the organism. These are frequently caused by environmental factors like exposure to UV rays or to certain chemicals. 
  • Gene mutation is a permanent alteration in the DNA sequence that makes up a gene. They are of two types: Hereditary mutations (inherited from parents) and Acquired mutation (occur at some time during a person's life).
So, the correct answer is 'Somatic mutation'

Multiple choice zoology excretory system of human disorders of excretory system disorders related to the excretory system functions and disorders of kidney

Assertion  :  Phenylketonuria is a recessive hereditary disease caused by the body's failure to oxidize an amino acid phenylalanine to tyrosine, because of a defective enzyme

Reason    :    It results in the presence of phenylalanine in the urine


  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion

  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion

  3. If the assertion is true but the reason is false

  4. If both the assertion and reason are false

  5. If the assertion is false but reason is true
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Phenylketonuria results when there is a deficiency of liver enzyme phenyl alanine hydroxylase that converts phenyl alanine into tyrosine. It results with a high level of phenyl alanine in blood, tissue fluids and urine.

So, the correct answer is 'If both the assertion and reason are true but the reason is not a correct explanation of the assertion'

Multiple choice sexually transmitted diseases stds and infertility reproductive health reproduction biology

Which one is a sex-related disease?

  1. Christmas disease

  2. Klinefelter's syndrome

  3. Phenylketonuria

  4. Albinism
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
In haemophilia, the blood does not clot as it should. Haemophilia is normally an inherited disorder. It happens because of a defect in one of the clotting factor genes on the X chromosome. Haemophilia tends to occur in males since the gene can be passed from mother to son. Males typically lack a second X chromosome so they are unable to make up for the defective gene. Most females have XX sex chromosomes while most males have XY sex chromosomes.
Haemophilia B, also known as "Christmas disease," occurs when a person lacks clotting factor IX.
So, the correct answer is 'Christmas disease'.
Multiple choice sexually transmitted diseases stds and infertility reproductive health reproduction biology

Assertion:  Males suffer from sex-linked disorders more often than females.

Reason: Sex-linked traits are mostly governed by recessive genes.

  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion

  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion

  3. If the assertion is true but the reason is false

  4. If both the assertion and reason are false

  5. If the assertion is false but reason is true
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Males have only one X chromosome, so any recessive sex-linked gene on that chromosome will be expressed. Females have two X chromosomes, so they must inherit two copies of the recessive gene to express the trait, making it much rarer for them.