Xylem and Phloem

Question 1

How is the xylem structured?

Answer 1

Hollow tubes with dead cells
No cytoplasm / nucleus
No cell walls at the ends
Strengthened by lignin
Contain pits at the side of the walls, lumen on the interior

Question 2

What does the xylem transport?

Answer 2

Water and mineral salts

Question 3

What direction does the xylem transport?

Answer 3

Up only

Question 4

How is the xylem specialised for its function?

Answer 4

Lignin: provides structural support to the cells as they are dead
Pits to pass water laterally
No organelles so water flow is not restricted

Question 5

How is the phloem structured?

Answer 5

Living cells (known as sieve tube elements)
Companion cells attached to sieve elements
No lignin present
Contains sieve plates and pores at each end
Contains plasmodesmata at the sides of each cell

Question 6

What does the xylem transport?

Answer 6

Carbohydrates
Assimilates (products of photosynthesis)

Question 7

What direction does the phloem transport?

Answer 7

All directions

Question 8

How is the phloem specialised?

Answer 8

Companion cells: involved in ATP production of the sieve elements
Plasmodesmata: allows communication and flow of substances such as minerals between cells
Perforated walls