concept 23 - BIO10008

explain the significance of the evolution of vascular tissue

allowed rigid structures and transport for water and nutrients, thus the plants could grow taller and maximise their photosynthesis rates.

define the two components of water potential

pressure potential and solute potential

explain the important role of water in plants

water is needed for photosynthesis and transpiration the driving force for water to transport from the soil to the atmosphere through the stomata. (transpiration occurs in the mesophyll cells diffusing due to water potential in the the intercellular space then the moisture diffuses out from the stomata)

increase of turgor pressure for rigid structure

transporting from source to sinks

nutrients that plants acquire through uptake via roots

nitrogen

difference between apoplast and symplast

apoplast is faster and symplast is slower

apoplast water movement

symplast water movement

role of casparian strip

two types of water conducting cells in plants

vessel element and tracheids they are both dead cells

structure features of water conducting elements that make them well adapted for transporting water

cohesion of water from their hydrogen bonds creates a unidirectional flow from the roots to the leaves

adhesion of water molecules to the xylem walls creates a capillary action allowing the water to flow up passively from the tension in the veins

transpiration is the driving force of water, where mesophyll cells diffuse into the the intercellular space to diffuse out of stomata to provide tension to pull water up as the mesophyll cell’s films shrink as it diffuses

water potential - water tends to flow to negative water potential thus, the water potential is more negative in the atmosphere

how does water move from soil to top of the plants

why is the movement of water in one direction

in drought conditions tall trees sometimes form air bubbles within xylem vessels called embolism or cavitations, with reference to the tension cohesion model explain what the impact of the formation of embolisms would have on water transport

summarise and explain how cohesion, adhesion, transpiration and water potential all contribute to the movement of water from the soil, past the Casparian strip and to the leaves in plants

compare and contrast the water use and transpiration and photosynthetic rates in:

full sun, water in soil plentiful

rainy over cast, water in soil plentiful

full sun, drought limited water in soil

describe the process of water and sugar transport in a plant emphasising the essential differences between the two