plant transport

how is the xylem tissue formed ?

meristem cells in the vascular cambium divide by mitosis to produce living precursor cells which differentiate into xylem cells

what are the diff features of xylem walls ?

primary cell wall cellulose is laid down
secondary spiral shaped cell wall lignin

lignin - provides support to withstand tension - waterproof

spiral thickening - deposition of lignin in a spiral manner - allows flexibility

pitted lignin walls - allows lateral movement for water to move out of xylem vessels to other tissues / cells

how do xylems have hollow cells ?

programmed cell death (PCD)
hydrolytic enzymes break down the nucleus , organelles and cytoplasmic macromolecules

why do xylems have hollow cells ?

no organelles to obstruct flow allows for easier water flow

no end walls - continuous water column - minimises resistance to water flow

describe adhesion / capillary in the xylem

hydrophobic lignin cant form h bonds w/ water

in the xylem walls there are pits and walls w/ exposed hydrophilic cellulose