xylem Flashcards
what adaptations does the xylem have
consists of dead cells
no end walls
pits (small gaps in the xylem wall
what are pits
small gaps in the xylem wall
what do xylem cell walls consist of
lignin
what are the benefits of lignin
water can adhere to lignin, and it provides strength to the xylem to prevent inward collapse
how are dead cells helpful
they consist of no organelles or cytoplasm which could possibly impede the flow
how are no end walls an adaptation
they form a continuous system of tubes for water transport
this allows water to move as a continuous column with no impeded flow
how are pits an adaptation
they allow for horizontal movement of water
what is adhesion
forces between the water molecules and hydrophillic lining of the xylem walls
what is cohesion
force between water molecules forming an unbroken column in the xylem
what is tension
pull generated by water evaporation.This creates a negative pressure inside the xylem
what does negative pressure inside the xylem mean
pressure is lower inside the xylem than outside of it
what is transpiration
evaporation of water as water vapour, from the leaves and shoots of plants. Usually through the stomata
what is the first step of mass transport of water
transpiration
diffusion of water vapour through the stomata. This lowers the water potential of the leaf cells and water moves from the higher water potential in the xylem to the leaf cells by osmosis
what is the second step of mass transport of water
water is drawn up the xylem which creates tension
what is the third step of mass transport of water
water molecules cohere together to form a continuous column of water
