Structure + functions of the xylem

Question 1

What are the 2 main functions of the xylem?

Answer 1

Transport water + mineral ions, mechanical support

Question 2

What does water movement require + what is the flow of materials?

Answer 2

Cohesion +adhesion

Flow of materials is up roots to shoots + leaves

Question 3

What are the main structures in xylem?

Answer 3

Xylem vessels - long, hollow structures made by several columns of cells fusing together end to end

Also composed of tracheids

Question 5

What are the walls composed of?

Answer 5

Dead cells with lignin, also has unlignified areas called bordered pits, which allow water exchange

Question 6

What different types of structures can lignin form?

Answer 6

Rings, spirals, or solid tubes with unlignified areas (bordered pits)

Question 7

What are the 2 other tissues associated with the xylem in herbaceous dicots?

Answer 7

• Thick walled xylem parenchyma = Packs around xylem vessels, storing food, + containing tannin deposits
• Tannin = Bitter chemical that protests plant tissues from attack by herbivores due to bad taste

Question 8

What are xylem fibres?

Answer 8

Long cells with lignified secondary walls, provide extra strength, dont transport water