Multiple Choice QuestionsIn a ring girdled plant
the shoot dies first
the root dies first
the shoot and root die together
the shoot and root die together
Which one gives the most valid and recent explanation for stomatal movements?
Transpiration
Potassium influx and efflux
Starch hydrolysis
Starch hydrolysis
Which one gives the most valid and recent explanation for stomatal movements?
Transpiration
Potassium influx and efflux
Starch hydrolysis
Starch hydrolysis
The movement of a gene from one linkage group to another is called
inversion
duplication
translocation
translocation
The function of leghemoglobin in the root nodules of legumes is
oxygen removal
nodule differentiation
expression of nif gene
expression of nif gene
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
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.
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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