Multiple Choice Questions

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Which of the following theory gives the latest explanation for the closure of stomata?

  • ABA theory

  • Munch Theory

  • Starch glucose theory

  • Active K+ transport theory


D.

Active K+ transport theory

As per 'Active K+ transport mechanism' accumulation of K+ ions occurs in the guard cells during the day inresponse to light. It increases the turgidity of guard cells, consequently stomata open.

During night, ions move out of the guard cells into surrounding epidermal cells consequently guard cells become flaccid and stomata close.


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The light phase of photosynthesis is called

  • Hill reaction

  • photo action

  • pigment action

  • chlorophyllous process


Who said that 'transpiration is a necessary evil'

  • Curtis

  • Andersen

  • Steward

  • J.C. Bose


Root hair absorbs water from soil through

  • turgor pressure

  • ion exchange

  • osmosis

  • DPD


In plants, water supply is due to

  • osmosis

  • imbibition

  • guttation

  • adhesion force


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Water in plants is transported by

  • cambium

  • phloem

  • xylem

  • epidermis


Which of the following exhibits a direct porportionality to transpiration

  • Light and RH

  • Temperature and RH

  • Temperature and wind

  • RH and wind


Most accepted theory for ascent of sap is

  • capillary theory

  • root pressure theory

  • pulsation theory

  • transpiration pull


The most important force which pulls water up in tall trees is

  • imbibition force

  • osmotic force

  • cohesive force

  • electromagnetic force


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Transpiration would be lowest when

  • wind velocity is high

  • enough water is in the soil

  • atmospheric RH is high

  • high temperature and light


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