Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

71.

Double fertilization means

  • fusion of nucleus of male gamete with the egg nucleus

  • fusion of two polar nuclei

  • fusion of sperm nucleus with secondary nucleus

  • fusion of one sperm nucleus with nucleus and fusion of other sperm nucleus with secondary nucleus


D.

fusion of one sperm nucleus with nucleus and fusion of other sperm nucleus with secondary nucleus

Double fertilization was first observed by Nawaschin (1892) in Lilium and Fritillaria and confirmed by Grignard. It is characteristic of angiosperms. In double fertilization first fertilization is normal and second, as it involves three nuclei is known as triple fusion.


72.

Micro-organism which act as a vehicle for foreign gene transfer in higher plants

  • Agrobacterium

  • E. coli

  • T.M.V.

  • Bacillus anihracis


A.

Agrobacterium

The bacterium-Agrobacterium acts as avehicle for transfer of DNA or genes from one organism to another organism because it infects all dicot plants.


73.

Restriction enzymes are used in genetic engineering, because they

  • can degrade harmful proteins

  • can join different DNA fragments

  • can cut DNA at specific base sequence

  • are nucleases that cut DNA at variable sites


C.

can cut DNA at specific base sequence

Restriction enzyme are also known as molecular knifes or molecular scissors. They are isolated from bacteria. They recognize specific base sequence in DNA and cleave both strands of it.


74.

Which is social foresting species

  • Leucaena leucocephala

  • Tectona grandis

  • Mangifera indica

  • Rosa indica


A.

Leucaena leucocephala

Leucaena leucocephala is commonly known as subabool. It is a very fast growing leguminous plant and therefore is commonly used as social foresting species.


75.

Which type of DNA is found in bacteria

  • Helical DNA

  • Membrane bound DNA

  • Straight DNA

  • Circular free DNA


D.

Circular free DNA

Bacteria are prokaryotic in nature, in which typical chromosomes are lacking. DNA is circular and naked as it is not surrounded by histones (basic proteins which are responsible for coiled structure of nucleosome).


76.

In terrestrial ecosystem such as forest, maximum energy is found in which trophic level

  • T1

  • T2

  • T3

  • T4


A.

T1

In almost all ecosystem the maximum amount of energy is found in 1st trophic level.


77.

DNA polymerase enzyme is required for synthesis of

  • DNA from RNA

  • RNA from DNA

  • DNA from DNA

  • RNA from RNA


C.

DNA from DNA

The enzyme needed for replication of DNA i.e. formation of DNA from DNA is DNA polymerase III. DNA replication is initiated by RNA primer which is later removed by DNA polymerase I.


78.

Which of the following statement is correct about DDT

  • It is a biomagnifying biodegradable pollutant

  • It is non biomagnifying biodegradable pollutant

  • It is biomagnifying non biodegradable pollutant

  • It is not a pollutant


C.

It is biomagnifying non biodegradable pollutant

DDT has been recently banned because it is non-biodegradable and biomagnifying pollutant. Biomagnification means the increase in amount of DDT in the body of organism along with the increase in trophic level. Hence, the amount of DDT in 1st trophic level will be minimum and in top consumer will be maximum.


79.

2n-1 condition represent

  • tetrasomy

  • trisomy

  • monosomy

  • multisomy


C.

monosomy

When changes involve only a few chromosome say one or two and not the entire genome, the phenomenon is called aneuploidy. Monosomy is a case of aneuploidy, when there is loss of one chromosome from a pair of homologue.


80.

The part of earth in which life exist is known as

  • Lithosphere

  • Biosphere

  • Atmosphere

  • Hydrosphere


B.

Biosphere

Biosphere is the part of earth where life exists.