The Xylem and Phloem

Question 1

Why do plants need a transport system?

Answer 1

So all cells receive a strong supply of the nutrients they need

Question 2

How does having lignified walls help the xylem to complete its function?

Answer 2

Provides strength against hydrostatic pressure and it is impermeable to water

Question 3

How does having no end plates help the xylem to complete its function?

Answer 3

allows mass flow of water

Question 4

What does the xylem carry?

Answer 4

Water and mineral ions

Question 5

What do sieve tube elements do in the phloem?

Answer 5

Transport assimilates (sugars) around plants

Question 6

What do companion cells do?

Answer 6

aid active transport into sieve tube elements

Question 7

What do plasmodesmata do in phloem tissue?

Answer 7

Allow the flow of substances between cytoplasm of different cells

Question 8

What does the phloem transport?

Answer 8

organic compounds (assimilates)

Question 9

Describe the structure and function of the vascular system in roots

Answer 9

Xylem arranged in X shape - provides resistance

Question 10

Describe the structure and function of the vascular system in stems

Answer 10

Xylem on the inside of bundle - provide support and flexibility

Phloem on the outside

Layer of meristem cells in the middle

Question 11

Describe the structure and function of the vascular system in the leaves

Answer 11

Xylem and phloem form midrib and veins

Question 12

Types of tissue in xylems

Answer 12

vessels

fibres

parenchyma cells

Question 13

Types of tissue in phloem

Answer 13

Sieve tube elements

Companion cells

Question 14

are xylems dead or alive

Answer 14

dead

Question 15

Direction of movement in xylems

Answer 15

Upwards

Question 16

Direction of movement in phloems

Answer 16

Upwards and downwards

Question 17

Materials present in cell wall of xylem

Answer 17

Lignin and cellulose

Question 18

Structure of the vascular system in the roots

Answer 18

Xylem is an X shape
Phloem between the arms of the X

Question 19

Structure of the vascular system in the stem

Answer 19

In a ring shape on the outside layer
Xylem on the inside
Phloem on the outside
Separated by a layer of cambium

Question 20

Structure of the vascular system in the leaves

Answer 20

The xylem is on top of the phloem in the “veins” of a leaf

Question 21

Structure of xylem vessels

Answer 21

Long thick walls which contain lignin
Lignin waterproofs the walls = cells die

Continuous column of dead cells

Some places there isn’t enough lignification = bordered pits = allow water to leave the vessel to join another vessel or pass into cells

Question 22

Structure of companion cells

Answer 22

dense cytoplasm
large nucleus
many mitochondria
Many plasmodesmata

Question 23

Why do companion cells contain lots of mitochondria

Answer 23

Require large amounts of ATP;
loading of sucrose into the phloem