Transport Systems In Dicotyledonous Plants

Question 1

what is the pressure in the phloem?

Answer 1

2000kPa

Question 2

why do multicellular plants need transport systems?

Answer 2

• metabolic demands
• size
• surface area:volume ratio

Question 3

what are dicotyledonous plants?

Answer 3

plants that make seeds containing two cotyledons.

Question 4

what are cotyledons?

Answer 4

organs that act as food stores for the developing embryo plant and form the first leaves when the seed germinates.

Question 5

what are herbaceous dicots?

Answer 5

dicot plants with soft tissues and a relatively short life cycle.

Question 6

what is a vascular system?

Answer 6

the transport vessels running through the stem, roots and leaves.

Question 7

what are the two main transport vessels in herbaceous dicots?

Answer 7

the xylem and the phloem.

Question 8

where are the vascular bundles in the stem?

Answer 8

around the edge of the stem for strength and support.

Question 9

where are the vascular bundles in the roots?

Answer 9

in the middle to help the plant withstand the tugging strains that result as leaves and stem moves in the wind.

Question 10

where are the vascular bundles in the leaf?

Answer 10

the midrib. helps support leaf structure.

Question 11

what is the function of the xylem?

Answer 11

• the transport of water and mineral ions.
• support.

Question 12

what is the function of the xylem?

Answer 12

• the transport of water and mineral ions.
• support.

Question 13

is xylem dead or alive?

Answer 13

dead.

Question 14

what is the direction of travel in the xylem?

Answer 14

from the roots to the shoots and leaves.

Question 15

what are xylem vessels like?

Answer 15

• long
• hollow
• made by several columns of cells fusing together end to end.

Question 16

what are the other two tissues associated with xylem?

Answer 16

• xylem parenchyma.
• xylem fibres.

Question 17

what do thicked wall xylem parenchyma do?

Answer 17

• packs around xylem vessels.
• stores food.
• contains tannin deposits.

Question 18

what is Tannin?

Answer 18

tannin is found in parenchyma tissue. it is a bitter, astringent-tasting chemical that protects plant tissues from attacking herbivores.

Question 19

what are xylem fibres?

Answer 19

long cells with lignified secondary walls that provide extra mechanical strength but do not transport water.

Question 20

what are the different ways lignin can be laid down in xylem vessels?

Answer 20

• rings
• spiral
• relatively solid tubes with lots of small unlignified areas called bordered pits.

Question 21

what are bordered pits?

Answer 21

unlignified areas where water leaves the xylem and moves into the other cells of the plant.

Question 22

is phloem dead or alive?

Answer 22

living

Question 23

what is the role of phloem?

Answer 23

transports food in the form of organic solutes around the plant from the leaves where they are made by photosynthesis.

Question 24

what is the flow of materials in the phloem?

Answer 24

from source to sink. can travel up or down the plant.

Question 25

what are the main transporting vessels of the phloem?

Answer 25

sieve tube elements.

Question 26

are phloem tubes lignified?

Answer 26

no

Question 27

what are the areas between phloem cells called?

Answer 27

the walls become perforated toform sieve plates. They let phloem contents flow through.

Question 28

what is the vacuole membrane called?

Answer 28

the tonoplast

Question 29

what happens when large pores appear in cell walls?

Answer 29

the tonoplast, the nucleus, and some other cells break down

Question 30

do mature phloem cells have a nucleus?

Answer 30

no

Question 31

what links companion cells to sieve tube elements?

Answer 31

plasmodesmata.

Question 32

what are plasmodesmata?

Answer 32

microscopic channels through the cellulose cell wall linking the cytoplasm of adjacent cells.

Question 33

do companion cells maintain their nucelus and organelles?

Answer 33

yes.

Question 34

what supporting tissues does phloem tissue contain?

Answer 34

fibres and sclereids.