These MP Board Class 11th Biology Notes for Chapter 11 Transport in Plants help students to get a brief overview of all the concepts.
MP Board Class 11th Biology Notes Chapter 11 Transport in Plants
→ Loss of water in the form of vapour from aerial part of the plants through stomata, lenticel or cuticle is called as transpiration.
→ Loss of water in the form of vapour from any surface of the plant body is called as evapora¬tion.
→ In stomatal transpiration guard cells control the opening and closing of stomata.
→ Loftfield has classified the plants into three groups on the basis of daily stomatal movement: (i) Alfalfa type, (ii) Potato type, (iii) Barley type.
→ Guard cells contain a large number of chloroplasts.
→ The inner wall of guard cells is thick while outer wall is thin. Both walls are elastic.
→ According to Curtis, ‘Transpiration is a necessary evil’.
→ The opening and closing of stomata is being controlled by turgidity and flaccidity of guard cells respectively.
→ Stomatal pores open when guard cells are fully turgid.
→ During daytime stomata opens because guard cells photosynthesize and produce osmotically active substance.
→ Osmotic theory of stomatal opening and closing was proposed by Von Mohl (1856).
→ Starch ⇌ sugar hypothesis of stomatal opening and closing was proposed by Lloyd.
→ According to Steward, stomata is open during daytime when starch is converted into sugar at high pH and closed when sugars are converted into starch at low pH.
→ Phosphorylase enzyme was discovered by Hanes. It converts starch into glucose-1 -phosphate.
→ According to Steward, the OP of guard cells is not effected unless glucose-1 -phosphate is not converted into glucose and inorganic phosphate.
→ The rate of transpiration is measured with the help of potometer.
→ K+ ion transport method for stomatal opening and closing was proposed by Health, Zelitsch and Ruscka.
→ Proton transport method for the opening and closing of stomata was proposed by Levitt in 1974.
→ According to Levitt, when K+ ions enter the guard cell, stomata opens.
→ Loss of water in the form of water droplets from the margins of leaves is called as guttation.
→ Guttation takes place through hydathodes.
→ The cavity and loose tissue present below the hydathodes is called epithem.
→ In succulent plants stomata are open during daytime and closed during night-time. It is called as photoactive opening of stomata and plants are called photoactive.
→ The term guttation was proposed by Burgrstein, for exudation of water in the form of liquid from the margins of the leaves.
→ Xerophytic plants have higher rate of transpiration than mesophytes.
→ Percentage of water in the soil at permanent wilting point is called wilting coefficient.
→ Abscisic acid (ABA) results in the closure of stomata. It appears to block the active excretion of H+ ions from guard cells.
→ Plants can utilize only capillary water of the soil.
→ Difference between the diffusion pressure of a solution and its solvent is called as diffusion pressure deficit (DPD).
DPD = OP – TP or WP.