Module 3 - Transport in Plants

Question 1

what is the need for plant transport systems?

Answer 1

• metabolic demands
• size
• surface area:volume

Question 2

metabolic demands in plants:

Answer 2

make own glucose for phaotosynthesis
removal of waste products
transport of hormones from source to sink
absorption of mineral ions

Question 3

size of plants:

Answer 3

pelennial plants live for a long time therefore can become very large
plants need effective transport systems to move substances both up and down form tip of roots to leaves and stem

Question 4

SV:V in plants:

Answer 4

leaves are adapted to have relativly large sa:v for exchange of gas with the air
yet the plant as a whole has a small SA:V - theyrefore cannot rely on just diffusion alone

Question 5

what are dicot plants?

Answer 5

plant that contains two cotyledons (embryos) that act as food stores for the developing embryo

Question 6

what are the characterisitics of herbaceous dicots?

Answer 6

soft tissue
relativly short life cycle

Question 7

characterisitics of woody dicots?

Answer 7

hard, lignified tissue
long life cycle

Question 8

what is the vascular system of herbaceous dicots?

Answer 8

xylem and phloem arranged together in vascualr bundles at he edge to give strengeth and support

Question 9

what is the midrib of dictot plants?

Answer 9

main vein carrying the vascular tissue through the organ - helps support structure of plant

Question 10

what is the function of the xylem?

Answer 10

transport of water and minerals
support

Question 11

what is the direction of transportation in the xylem?

Answer 11

UPWARDS from root to shoots and leaves

Question 12

what is the structure of the xylem?

Answer 12

long
hollow
made by several coloums of cells fusing together end to end

Question 13

what are the two other tissues associated with the xylem in herbaceous dicots?

Answer 13

thick walled xylem parenchima
xylem fibres

Question 14

what is the purpose of thick walled xylem parenchyma?

Answer 14

packs around xylem vessels
store food
contain tannin deposits

tannin = bitter tasting chemical that protects plant from attack

Question 15

what is the purpose of xylem fibres?

Answer 15

long cells with lignified secondary walls that provide extra mechanical strength (do not transport water)

forms rings, spiraled, solid tubes with small unlignified areas called boardered pits
where water leaves xylem moving to other areas of plant

Question 16

what is the function of the pholem?

Answer 16

liviing tissue that transports food in form of organic solutes

supplies plant with sugars and amino acids needed for cellular respiration

Question 17

what is the direction of transport in phloem?

Answer 17

both UP AND DOWN the plant

Question 18

what is the structure of the phloem?

Answer 18

sieve tube elements - long hollow structure + non-lignified
sieve plates - let substances through phloem
companion cells - connect to STE by plasmodesmata (they’re very active cells)