Plant Stems

Question 1

What are the 3 types of plant vessel?

Answer 1

• Phloem
• Xylem
• Schlyrenchma fibres

Question 2

What is the function of the xylem?

Answer 2

• Transports mineral ions and water up the plant

- Structural support

Question 3

What do xylem vessels look like?

Answer 3

Very long tube like structures formed from dead cells joined end to end

Question 4

How are xylem vessels found together?

Answer 4

Bundles

Question 5

What are the proportions of xylem vessels like?

Answer 5

Cells are longer than they are wide

Question 6

What is the lumen of xylem vessels like?

Answer 6

Hollow with no cytoplasm

Question 7

What are the walls of the xylem vessels like?

Answer 7

No end walls

Question 8

What allows the water and mineral ions to pass up xylem vessels?

Answer 8

It is an uninterrupted tube

Question 9

How do xylem vessels support the plant?

Answer 9

They are thickened with a woody substance – lignin

Question 10

How do water and mineral ions move in and out of xylem vessels?

Answer 10

Through pits in the walls where there is no lignin

Question 11

What is the function of the sclerencyhma fibres?

Answer 11

• Structural support

- NOT transport

Question 12

How are the sclerencyhma fibres similar to the xylem vessels? 3

Answer 12

• Longer than they are wide
• Hollow lumen
• Thickened with lignin

Question 13

How are sclerencyhma fibres different to xylem vessels?

Answer 13

• More cellulose
• Have end walls
• Don’t contain pits

Question 14

What is the function of the phloem tissue?

Answer 14

Transport soluble organic solutes e.g glucose from where they are made to where they are needed – translocation

Question 15

How is the phloem tissue similar to the xylem tissue?

Answer 15

Formed from cells arranged in tubes

Question 16

How is the phloem different to the xylem tissue?

Answer 16

Used only as a transport tissue, not support

Question 17

What 2 types of cell does phloem contain?

Answer 17

• Sieve tubes elements

- Companion cells

Question 18

What are sieve tube elements?

Answer 18

• Living cells joined end to end to create sieve tubes

- Their end walls have many holes in them to allow water through

Question 19

What are sieve tube element cells like?

Answer 19

• Very thin layer of cytoplasm
• Few organelles
• No nucleus

Question 20

How are the cytoplasm of sieve tube element cells connected?

Answer 20

Through holes in the sieve plates

Question 21

Why can’t sieve tube elements survive on their own?

Answer 21

Lacks nucleus and other organelles needed for cell function

Question 22

What is the function of the companion cells?

Answer 22

To carry out living processes for both itself and the sieve tube element cells

Question 23

Give an example of a function of the companion cell

Answer 23

To provide energy for the active transport of solutes

Question 24

Where are xylem vessels and phloem tissue found in the stem?

Answer 24

Grouped together to form vascular bundles

Question 25

Where is the sclerencyhma tissue found in the stem?

Answer 25

On the outside of vascular bundles

Question 26

What is the function of starch?

Answer 26

- Stores excess glucose in a plant | - When the plant needs more glucose it breaks down starch

Question 27

What is cellulose made up of?

Answer 27

Long unbranched chains of beta glucose joined by 1-4 glycosidic bonds

Question 28

How is cellulose different to starch?

Answer 28

Glycosidic bonds are straight so the cellulose chains are straight

Question 29

How are cellulose chains linked together?

Answer 29

Large numbers of hydrogen bonds form strong threads called microfibrils

Question 30

What do the strong threads in cellulose mean?

Answer 30

Cellulose can provide structural support for cells

Question 31

What feature of the cell wall gives plant fibres strength?

Answer 31

Made up of cellulose microfibrils in a net like arrangement

Question 32

What is the function of cellulose?

Answer 32

Forms cell walls in plants

Question 33

What else other than cellulose makes plant fibres strong?

Answer 33

Secondary thickening of cell walls

Question 34

What happens in the secondary thickening of cell walls?

Answer 34

- When structural plant cells e.g xylem and schlerenchyma have finished growing - They provide a secondary cell wall between the normal cell wall and the cell membrane - Secondary cell wall is thickened with more of a woody substance called lignin