Multiple Choice Questions

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Photorespiration is favoured by

  • high O2 and low CO2

  • high CO2 and low O2

  • high temperature and low O2

  • high humidity and temperature


A.

high O2 and low CO2

Photorespiration is a respiratory process in many higher plants by which they take up oxygen in the light and give out some carbon- dioxide.

Oxygen is a competitive inhibitor of CO2 fixation. Increase in O2 concentration would favour the uptake of oxygen by Rubisco leading to increase in photorespiration.


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What are the sex organs provided in some bacteria?

  • Circular DNA

  • Gametes

  • Sex pili

  • Plasmid


The formation of canal system in sponges is due to

  • reproduction

  • porous walls

  • folding of inner walls

  • gastro- vascular system


The term 'Meiosis' was given by

  • Johansen

  • Knoll and Ruska

  • A. Flemming

  • Farmer and Moore


2,4- D is an effective

  • fungicide

  • weedicide

  • rodenticide

  • wormicide


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Cochineal insects have proved very useful for

  • rodents control

  • Parthenium control

  • cactus prevention

  • Eicchornia prevention


Which typical stage is known for DNA replication?

  • Metaphase

  • G1- phase

  • S- phase

  • G2- phase


'Gymnosperm' have how many species?

  • 1000

  • 900

  • 640

  • 300


Which vertebrate orgen receives only oxygenated blood?

  • Gill

  • Lung

  • Spleen

  • Liver


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The true statement about 'green-house effect' is that it is

  • caused only by CO2

  • caused by CO2, CFCs, CHand NO2 gases

  • caused by combination of many gases

  • none of the above