Multiple Choice Questions

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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


D.

all red flowered

The red colour of flower dominates upon white colour of flower. In the present varieties both parents are of pure variety, therefore, the offsprings will be all heterozygous red flowered as shown below:

Parents                           RR                            rr

                             (Red flowered)           (White flowered)

Gametes                     R          R                 r          r

F1 generation                 Rr         Rr        Rr         Rr

(offspring)                  (Heterozygous red flowered plants)


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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.


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

  • epistatic

  • supplementary

  • hypostatic

  • codominant


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.


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


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Pure line breed refers to

  • heterozygosity only

  • heterozygosity and linkage

  • homozygosity only

  • homozygosity and self assortment


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.


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


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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.


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