Multiple Choice QuestionsWhich of the following facilitates opening of stomatal aperture?
Contraction of outer wall of guard cells
Decrease in turgidity of guard cells
Radial orientation of cellulose microfibrils in the cell wall of guard cells
Radial orientation of cellulose microfibrils in the cell wall of guard cells
The water potential of pure water is
Zero
Less than zero
More than zero but less than one
More than zero but less than one
Which of the following elements is responsible for maintaining turgor in cells?
Magnesium
Sodium
Calcium
Potassium
Some functions of the nutrient element are given below
The concerned nutrient is
Cu
Fe
Ca
Mo
Tyloses an outgrowth from ray or axial parenchyma cell into the lumen of a vessel, which partially or completely blocks the cavity are present in
Periderm
Heart wood
Sap wood
Secondary cortex
Most accepted theory for ascent of sap is
capillary theory
root pressure theory
pulsation theory
transpiration pull
D.
transpiration pull
Transpiration pull or the suction force is the force which aids in drawing the water upward from roots to leaves. In leaves, some amount of water is used for photsynthesis and excess of water is released into atmosphere through openings called as stomata.
Root Pressure Theory is the transverse osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves.
Pulsation theory or Vital force theory was not accepted because living cells are not involved in the ascent of sap as water continue to rise upwards in the plant.
Capillarity Theory is the capillarity movement of water due to adhesion and cohesion forces balanced by downward pull of gravity.
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
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