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GCSE Biology help

is it true that lignin starts to build up in xylem cells in which they start to lose organelles and horizontal cell walls?

ASAP response plz
@BrightBlueStar11

Good morning young lady/.man - sorry you have not had any help yet!

Lignin is the tough substance that gives wood its strength i.e. it is deposited in dead xylem with loss of organelles and the walls that separate individual xylem cells ["horizontal walls", which are like a sieve cos they need to be permeable to water oc].

Lignin is a phenolic polymer [phenol is a benzene ring with one -OH group, i.e. an aromatic alcohol] that cross-links with cellulose fibres in the plant cell wall, conferring great strength.

REMINDER:
Cell wall chemistry:-
PLANTS: cellulose
BACTERIA: peptidoglycan
FUNGI: chitin.

Enjoy your breaky - I shall now dig into my second!

Be safe!
M.
Original post by BrightBlueStar11
is it true that lignin starts to build up in xylem cells in which they start to lose organelles and horizontal cell walls?

ASAP response plz

Hi BBS11, hope you're well.
Lignin adds compressive strength and stiffness to the plant cell wall and is believed to have played a role in the evolution of terrestrial plants by helping them withstand the compressive forces of gravity. Lignin also waterproofs the cell wall, facilitating the upward transport of water in xylem tissues.
Hope this helps.

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