lecture 6 Flashcards
what are tracheids
primitive water conducting elements
where are tracheids found?
gymnosperm and angiosperm
what to tracheids look like?
long and thin with tapered ends
what is a pit-pair
two tracheids opposite one another at the ends. establishes a low-resistance pathway
what is a vessel element
advanced water conducting element (stacked to make a vessel)
where are vessels found?
only in angiosperm
special feature of vessel elements and function
perforation plate to transfer water more easily
are wider conduits more or less conductive?
more
are large vessels always better?
no, good for lots of water movement but can lead to bubbles and can be more susceptible to environmental damage
what is cavitation in the xylem?
a condition where air bubbles move into a vessel
what is a embolism?
the blocking of a vessel or tracheid by an air bubble or cavity
can embolisms spread between vessels?
yes
what do pit membranes do?
permit water flow and limit embolism spread
are vessels or tracheids more vulnerable to embolisms?
vessels
can embolisms spread from vessel element to vessel?
Yes, will fil entire vessel
