Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

71.

Only one of the following four ways through which AIDS can spread?

  • Infected needles and syringes

  • Through mosquito bites

  • Looking after AIDS patient

  • Shaking hands, coughing, sneezing, hugging


A.

Infected needles and syringes

There are three main router for transmission of HIV, ie, AIDS virus. These are through sexual intercourse, transmission through blood transfusion, blood products, contaminated equipments, and from mother to baby. Infected needles and syringes (ie, equipments) are most efficient method of HIV infection.


72.

Indicate, the inheritance of which of the following is controlled by multiple alleles?

  • Colourblindness

  • Sickle cell anaemia

  • Blood group

  • Phenylketoneuria


C.

Blood group

A particular gene has been found to occur in two alternative forms or allelomorphs. The existence of more than two allelic forms of a gene is called multiple allelism and the alleles as multiple alleles, eg, blood group in human.


73.

The equation NnNt= B represents, which of the following?

  • Natality

  • Growth rate

  • Mortality

  • All of these


A.

Natality

Natality or birth rate is the rate of production of new individuals per unit of population per unit time through birth. Natality is expressed as Nnt and NnNt = Specific natality rate.

 


74.

Filariasis is caused by

  • dead adult filariae

  • microfilariae

  • biting of filarial worm

  • presence of bacteria in filarial wall


B.

microfilariae

Filariasis also called elephantiasis is caused by Wuchereria bancrofti or filarial worm. It spreads by bite of Culex mosquito.


75.

Identify which one of the following is an example, of incomplete ecosystem?

  • Grassland

  • Cave

  • River

  • Wetland


B.

Cave

Ecosystems are made up of biotic and abiotic components. Cave ecosystem is incomplete because it does not have all the biotic and abiotic (specially) components.


76.

The absence of which clotting factor leads to haemophilia-A?

  • Factor VII

  • Factor VIII

  • Factor IX

  • Factor X


B.

Factor VIII

Haemophilia-A is characterized by lack of antihaemophilic globulin (factor VIII). Haemophilia is caused due to X-linked recessive gene.


77.

Which of the following conditions is related to haemophilia?

  • A responsible recessive gene present in the X-chromosome

  • A responsible dominant gene presentin the X-chromosome

  • A responsible dominant gene present in the Y-chromosome

  • A responsible dominant gene present in the autosomal chromosome


A.

A responsible recessive gene present in the X-chromosome

Haemophilia is the most serious and notorious disease which is more common in man than in woman. The person which contains the recessive gene for haemophilia lacks normal clotting substance (thromboplastin) in blood so, amino injuries cause continuous bleeding and ultimate death. It is X-linked disease.


78.

Down's syndrome occurs as a result of

  • trisomy

  • tetrasomy

  • autopolyploidy

  • allopolyploidy


A.

trisomy

Down's Syndrome is Trisomy of 21st chromosome. It is characterized by mental retardation, short stature with stubby fingers and heart defects.


79.

Active immunity development is related to

  • natural killer cells

  • memory cells

  • helper T cells

  • suppressor T cells


B.

memory cells

Active immunity involves the active functioning of the person's own immune system which leads to synthesis of antibodies and or the production of immunologically active cells.


80.

Passive immunity can be obtained through

  • antigens

  • vaccines

  • antibiotics

  • antibodies


D.

antibodies

In passive immunity, antibodies from one individual are passed into another individual. They give immediate protection unlike active immunity which takes a few days or weeks to build up. However, it only provides protection against infection for a few weeks.