The rupture and fractionation do not usually occur in the water

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 Multiple Choice QuestionsMultiple Choice Questions

11.

In a ring girdled plant

  • the shoot dies first

  • the root dies first

  • the shoot and root die together

  • the shoot and root die together

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12.

Which one gives the most valid and recent explanation for stomatal movements?

  • Transpiration

  • Potassium influx and efflux

  • Starch hydrolysis

  • Starch hydrolysis

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13.

Which one gives the most valid and recent explanation for stomatal movements?

  • Transpiration

  • Potassium influx and efflux

  • Starch hydrolysis

  • Starch hydrolysis

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14.

The movement of a gene from one linkage group to another is called

  • inversion

  • duplication

  • translocation

  • translocation

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15.

The function of leghemoglobin in the root nodules of legumes is 

  • oxygen removal 

  • nodule differentiation

  • expression of nif gene

  • expression of nif gene

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16.

Guttation is the result of 

  • diffusion

  • transpiration

  • osmosis 

  • osmosis 

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17.

Carrier ions like Na+ facilitate the absorption of substance like

  • amino acids and glucose

  • glucose and fatty acids

  • fatty acids and glycerol

  • fatty acids and glycerol

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18.

Guard cell help in

  • protection against grazing

  • transpiration

  • guttation

  • guttation

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19.

The rupture and fractionation do not usually occur in the water column in vessel/tracheids during the ascent of sap because of 

  • lignified thick walls

  • cohesion and adhesion

  • weak gravitational pull

  • weak gravitational pull


B.

cohesion and adhesion

The Vertical conduction of water from root to aerial parts of the plant is called ascent of sap. The water molecules remain joined to each other due to a force of attraction called cohesion force. This attraction is due to the presence of hydrogen bonds between them. The magnitude of this force is very high, therefore, the continuous water column in the xylem cannot be broken easily due to the force of gravity or other obstructions offered by internal tissues in the upward movement of water. This adhesive property of water, ie, the attraction between the water molecules and the walls of xylem ensures the continuity of water column in xylem.

Due to transpiration water evaporates to outer atmosphere through stomata. As a result leaf cells develop low water potential and water from leaf veins moves into leaf cells. They xylem of the main stem. A pressure (pull) is thus, exerted by all the leaves on the stems, which is called transpiration pull. This is strong enough to pull up the column of water to a great height.

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20.

Passage cells are thin-walled cells found in

  • endodermis of roots facilitating rapid transport of water from cortex to pericycle

  • phloem elements that serve as entry points for substance for transport to other plant parts

  • testa of seeds to enable emergence of growing embryonic axis during seed germination

  • testa of seeds to enable emergence of growing embryonic axis during seed germination

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