Multiple Choice Questions

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Gene which suppresses other gene's activity but does not lie on the same locus is called as

  • epistatic

  • supplementary

  • hypostatic

  • codominant


A.

epistatic

The phenomenon by which a gene suppresses the phenotypic expression of a non- allelic gene is called epistasis. In F2 generation, the ratio for epistatic gene is 12 : 3. 

The alleles which do not show dominant recessive relationship and are able to express themselves independently when present together are called co- dominant alleles.

Supplementary genes are a pair of non- allelic genes, one of which produces its effect independently in the dominant state while the dominant allele of the second gene is without any independent effect. Although, it is able to modify the effect of the former to produce a new trait.


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Assertion: Persons suffering from haemophilia fail to produce blood clotting factor VIII.

Reason: Prothrombin producing platelets in such persons are found in very low concentration.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


If a homozygous red-flowered plant is crossed with a homozygous white-flowered plant, the offsprings will be

  • half- white flowered

  • half- red flowered

  • all white flowered

  • all red flowered


Assertion : A gamete may carry either of the traits but not both.

Reason : This is Mendel's second law or law of independent assortment.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


Assertion: Blood group 'O' have anti-A & antiB antibodies.

Reason: It does not have any antigens.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


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Assertion : Haemophilia is a recessive sex linked disease.

Reason : Haemophilia occurs due to mutation of a structural gene on chromosome 15.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


XO-chromosomal abnormality in human beings causes

  • Turner's syndrome

  • Down's syndrome

  • Klinefelter's syndrome

  • None of these


The distance between two genes in a chromosome is measured in cross-over units which represent

  • ratio of crossing over between them

  • percentage of crossing over between them

  • number of crossing over between them

  • none of these.


Pure line breed refers to

  • heterozygosity only

  • heterozygosity and linkage

  • homozygosity only

  • homozygosity and self assortment


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Assertion: A geneticist crossed two plants, he got 50% tall and 50% dwarf progenies.

Reason: It follows Mendelian law as one of the parent plant might be heterozygous.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


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