Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

71.

Among plants "pheromones" are secreted by the cells of the following plants for given function

  • all plants for growth and development

  • Yeast for facilitating mating

  • all fungi for sexual reproduction

  • Rhizopus for formation of zygospore


B.

Yeast for facilitating mating

Pheromone is a substance secreted to outside by an individual and received by a second individual of the same specie in which it induces a specific reaction e.g. fusion of two yeast cells during sexual reproduction.


72.

For the formation of tetrasporic embryosac, how many megaspore mother cells are required?

  • 1

  • 2

  • 3

  • 4


D.

4

Tetrasporic is the development when all the four megaspore nuclei takes part in the formation of the female gaemtophyte (embryo sac). In tetrasporic embryo sac, meiosis is not accompained by wall formation.


73.

DNA replication generally proceeds in a

  • 3 direction

  • 5 direction

  • 3 direction

  • 5 direction


A.

3 direction

DNA is made up of double helix of two complementary strands. Both the strands get seperated during replication. Each strand of the original DNA molecule then serves as a template for the production of its counterpart, hence, a process is known as semi- conservative replication.

DNA synthesis or replication always proceeds in 5'3' direction because DNA polymerase acts on the 3'- OH of the existing strand for adding the free nucleotides.


74.

Which of the following workers are related as ecologist, palaeobotanist and embryologist respectively?

  • B. Salmi, R. Mishra, P. Maheshwari

  • R Mishra, B. Sahni, P. Maheshwari

  • B. Sahni, P. Maheshwari, R Mishra

  • P. Maheshwari, R Mishra, B. Sahni


B.

R Mishra, B. Sahni, P. Maheshwari

Prof. Ramdeo Misra is known as the "Father of Ecology" in India. He obtained his Ph. D in Ecology in 1937 under Prof. W. H. Pearsall.

Prof. Birbal Sahni is called "Father of Indian Palaebotany".

Prof. P. Maheshwari is called "Father of Indian Embryology".


75.

The gases that produce green house gases are

  • CH4, CFCs, CO2

  • CO2, N2O, H2

  • CFCs, NO2, O2

  • CO2, N2, water vapour


A.

CH4, CFCs, CO2

Green house effect is the CO2 effect. It is due to CO2 layer in atmosphere and also by CFCs, SO2, NO2, CH4. These gases come from factories, automobile, agriculture, refrigerators, deforestation. These gases entrap the solar heat and prevents the escape of heat from earth to outer space, thus increasing the temperature of earth which further leads to global warming.


76.

Increase in toxic concentration from one trophic level to another trophic level is called

  • ecological toxification

  • bio- magnification

  • bioconcentration

  • cytological effect


B.

bio- magnification

The phenomenon through which certain pollutants (toxic substances) get accumulated in trophic level in increasing concentrations along the different trophic level is called biological magnification or ecological magnification.

Bioconcentration is the process by which a chemical concentration in an aquatic organism exceeds in water as a result of exposure to a waterborne chemical.


77.

What's the difference between RNA and DNA?

  • Base

  • Sugar

  • Sugar and base

  • Phosphate


C.

Sugar and base

DNA has deoxy ribose pentose sugar and four nitrogenous basesi.e.Adenine (A), Guanine (G), both are purines; Cytosine (C) and Thymine (T), both are pyrimidines.

RNA has ribose pentose sugar and four nitrogenous bases as in DNA except Uracil (U) in place of Thymine (T).


78.

If decomposers are removed what will happen to the ecosystem?

  • Energy cycle is stopped

  • Mineral cycle is stopped

  • Consumers cannot absorb solar energy

  • Rate of decompostion of mineral increases


B.

Mineral cycle is stopped

Decomposers are heterotropic organisms, mostly bacteria and fungi which live on dead organic matter or detritus. They release different enzymes from their bodies into the dead and decaying plant and animal remains. The extra cellular digestion of the dead remains, lead to the release of simple inorganic substances.


79.

The Triticale is an intergeneric hybrid between

  • wheat and maize

  • maize and rye

  • wheat and rye

  • bajra and wheat


C.

wheat and rye

The Triticale is the first man made cereal. It is formed by a cross between wheat (Triticum) and rye (Secale cerale) followed by allopolyploidy (multiplication of non- homologous chromosomes).

Triticum sp×Secale cerale

Diploid

Allopolyploidy

Triticale


80.

Which of the following is used as green manure?

  • Azolla

  • Azadirachta

  • Crotolaria juncea

  • Hevea brassiliansis


C.

Crotolaria juncea

Crotolaria juncea, ia a common name of sunn hemp. It is a quick growing crop. It is cultivated and ploughed under to incorporate it into the soil. A green manure crop supplies organic matter and additional nitrogen and also exercises a protective action against erosion and leaching.