Xylem and Phloem

Question 1

What does xylem transport and the direction?

Answer 1

Water and mineral ions from roots to leaves

Question 2

What does phloem transport and the direction?

Answer 2

Assimilates (mainly sucrose and amino acids) around the plant

Question 3

Why are xylem and phloem both tissues?

Answer 3

As they are made from different cell types

Question 4

What structures make up xylem?

Answer 4

-Xylem Vessels
-Xylem Parenchyma
-Cell Walls
-Annular lignin
-Spiral lignin
-Bordered Pits

Question 5

What are xylem vessels?

Answer 5

long empty tubes formed from cells called vessel elements

Question 6

What are xylem parenchyma?

Answer 6

forms packing tissue to separate and with xylem fibres, support the xylem vessels

Question 7

What is lignin (annular and spiral)?

Answer 7

It is formed by lignification-it waterproofs and strengthens the vessels so they can withstand pressure of water and help support the plant

Question 8

What are bordered pits?

Answer 8

Allow water minerals to move between vessels and into surrounding cells

Question 9

What are examples of the minerals that are transported?

Answer 9

Magnesium
NO3
Potassium
Phosphates

Question 10

What is the first adaption of xylem?

Answer 10

Lignin is usually arranged in rings or spirals

Question 11

Why is this adaptation useful?

Lignin is usually arranged in rings or spirals

Answer 11

To allow felxibility preventing the stem from breaking
-if it was continuous, stem would be rigid and unable to bend

Question 12

What is the second adaptation of xylem?

Answer 12

Xylem die once formed (happens during lignification)

Question 13

Why is this adaptation useful?

Xylem die once formed (happens during lignification)

Answer 13

So that xylem vessels form long tubes and there is nothing to disrupt or get in the way of the transpiration stream

Question 14

What is the third adaptation of xylem?

Answer 14

No sieve plates inbetween vessel elements-the cell walls inbetween them decay away completly once the xylem vessel has formed

Question 15

Why is this adaptation useful?

No sieve plates inbetween vessel elements …..

Answer 15

So there are no organelles/cytoplasm to get in the way of the transpiration stream

Question 16

What is the fourth adaptation of xylem?

Answer 16

Xylem vessles have a larger diameter than phloem vessels

Question 17

Why is this adaptation useful?

Xylem vessles have a larger diameter than phloem vessels

Answer 17

Plants need to transport more water than they do assimilates

Question 18

What structures make up phloem?

Answer 18

-Sieve tube
-Sieve tube element
-Sieve plate
-Companion cell
-Phloem parenchyma

Question 19

What are sieve tubes?

Answer 19

Don’t have lignin in their walls so they are thinner than xylem so don’t help to support the plant

Question 20

What are sieve tube elements?

Answer 20

Elongated living cells that form sieve tubes

Question 21

What are Phloem parenchyma?

Answer 21

Along with Phloem fibres and phloem parenchyma helps support the sieve tubes

Question 22

What is the first adaptation of phloem?

Answer 22

There are sieve plates in between the sieve tube elements (they don’t decay away completely like in xylem)

Question 23

Why is this adapatation useful?

There are sieve plates in between the sieve tube elements

Answer 23

To protect the plant-if a plant is attacked, enarby sieve plates can ‘close’ to protect adjacent cells and/or their assimilates
-also help to maintain pressure inside the sieve tube (important in trasnlocation)

Question 24

What is the second adaptation of phloem?

Answer 24

Sieve plates have lots of pores in them

Question 25

Why is this adapatation useful?

Sieve plates have lots of pores in them

Answer 25

To connect the cytop[lasm of adjacent cells which allows them to communicate with eachother (e.g. via hormones).
-also allow assimilates to pass through

Question 26

What is the third adaptation of phloem?

Answer 26

Sieve tube elements have no nucleus, a thin layer of cytoplasm and a few organelles (e.g. mitochondria)

Question 27

Why is this adapatation useful?

Sieve tube elements have no nucleus,thin cytoplasm & few organelles

Answer 27

To make it easier for the assimilates to pass through

Question 28

What is the fourth adaptation of phloem?

Answer 28

Each sieve tube element is associated with a companion cell

Question 29

Why is this adapatation useful?

Each sieve tube element is associated with a companion cell

Answer 29

-To carry out the living functions for the sieve tube element.
-CC also contain nuclues and many mitochondria to release energy for active transport/loading sucrose into sieve tubes during translocation

Question 30

How are sieve tube elements and companion cells connected?

Answer 30

By plasmodesmata