water transport

Question 1

state the function of the spiral band of lignin and explain why it is important that the xylem vessel is lignified this way (4)

Answer 1

1) strengthens xylem wall - to prevent collapse of xylem
2) improves adhesion of water molecules - reduces water loss through wall

Question 2

explain the function of pits (2)

Answer 2

1) allows water to move between vessels to bypass blockage
2) supplies water to other tissues