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Biology

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

Which one of the following statements is correct?

  • Extensive use of chemical fertilizers may lead to eutrophication of nearby water bodies

  • Both Azotobacter and Rhizobium fix atmospheric nitrogen in root nodules of plants.

  • Cyanobacteria such as Anabaena and Nostoc are important mobilizers of phosphates and for plant nutrition in soil.

  • At present it is not possible to grow maize without chemical fertilizers.


A.

Extensive use of chemical fertilizers may lead to eutrophication of nearby water bodies

Eutrophication is caused by run off water from fertilized fields suburban lawns, feed lots and detergent rich sewage. It is phenomenon of nutrient enrichment of a water body.

Eutrophication is caused by run off water from fertilized fields suburban lawns, feed lots and detergent rich sewage. It is phenomenon of nutrient enrichment of a water body.


What is the term for the inflammation of cornea due to high absorption of UV-B radiation :
  • myopia
  • snow blindness
  • biomagnification
  • None of the above

B.

snow blindness

Which of the following pollutants is not produced by exhaust of motor vehicles ?
  • CO
  • Hydrocarbon
  • Fly-ash
  • NO

C.

Fly-ash

In the scrubber in the electrostatic precipitator the gases are passed through :
  • filter
  • lime
  • spray of water
  • both 2 and 3

D.

both 2 and 3

The meaning of BOD is :
  • Bacterial oxygen demand
  • Biological optimum density
  • Biochemical oxygen demand
  • Bioorganisation decay

C.

Biochemical oxygen demand

Ozone depletion will cause :
  • Forest fire
  • Pneumonia
  • Increased incidence of skin cancer
  • None of these

C.

Increased incidence of skin cancer