Multiple Choice Questions

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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


C.

If assertion is true but reason is false

Haemophilia is also known as bleeder disease. It is an example of sex linked inheritance in humans. It is either of two hereditary disorders in which the blood clots very slowly, due to a deficiency of either of two coagulation factors -

  1. Haemophilia A- It is due to deficiency of factor VIII (antihaemophilic factor)
  2. Haemophilia B- It is due to deficiency of factor IX (Christmas factor).

The patient may experience prolonged bleeding following any injury or wound, and in severe cases there is spontaneous bleeding into muscles and joints. It is controlled by a sex-linked gene, which means that it is almost exclusively restricted to males; women can carry the disease- and pass it on to their sons- without being affected themselves. The genes encoding factors VIII and IX have been used in gene therapy trials for haemophilia.

Mutations of a structural gene on chromosome 15 is the molecular basis of Marfan syndrome. It is due to dominant mutation resulting in the production of abnormal form of connective tissues and characteritic extreme looseness of joints.


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Pure line breed refers to

  • heterozygosity only

  • heterozygosity and linkage

  • homozygosity only

  • homozygosity and self assortment


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


Which part of the world has a high density of organism?

  • Deciduous forests

  • Grasslands

  • Tropical rain forests

  • Savannahs


Assertion : Antigen can be easily recognized because it has antigenic determinants.

Reason : The recognition ability is innate.

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

  • epistatic

  • supplementary

  • hypostatic

  • codominant


Assertion : Chlorofluorocarbons are responsible for ozone depletion.

Reason : Ozone level decreases by as much as 67% every year.

  • 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 : Vegetable oils are fats which are present in plant cells in soluble form.

Reason : Vegetable oils occur only in cells of embryo.

  • 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 : Pollution is always caused by human activities.

Reason : Pollution is not different from contamination.

  • 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 : The earliest fossil form in the phylogeny of horse is eohippus.

Reason : Eohippus lived during the early pliocene epoch.

  • 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