Part One Transport Plants

Question 1

Why plants need transportation system

Answer 1

• transport water and minerals from the roots to leaves

- transport sugars from the leaves to the rest of plant

Question 2

Vascular tissue

Answer 2

Xylem - water and soluble mineral ions upwards

Phloem - assimilates, such as sugars, travel up or down

Question 3

Xylem and phloem in young root

Answer 3

Xylem core
Phloem found between arms of x like xylem bundle
This arrangement provides strength - w/ stand pushing forces roots exposed to.
Endodermis - meristem cells (pericycle)

Question 4

Xylem and phloem in the stem

Answer 4

Non- woody and young woody plants bundles separate and discrete.
Older Woody plants continuous ring - strength and flexibility to withstand bending forces of stems and branches

Xylem inside
Cambium middle (meristem)
Phloem outside

Question 5

Xylem and phloem in the leaf

Answer 5

Bundles from the midrib and veins of a leaf

Xylem on top of phloem

Question 6

Xylem consists of

Answer 6

Vessels to carry water and dissolved mineral ions
Fibres support
Living parenchyma cells (packing tissue) - separate and support vessels

Question 7

Xylem vessels

Answer 7

Lignin impregnates walls
Lignin may be spiral, annular(rings) or reticulate (network broken rings).
Lignification not complete – boarded pits.

Question 8

Xylem adaptations

Answer 8

Dead cells aligned end to end to form a continuous column
The tubes are narrow so watercolour doesn’t break easily and capillary action affective
Border pits allow side movement of water
Lignin patterned to allow plant to grow and stretch

Question 9

Flow of water in xylem not impeded because

Answer 9

No cross walls
No cell contents, nucleus or cytoplasm
Lignin thickening prevents walls from collapsing

Question 10

Phloem made up of

Answer 10

Sieve tubes
Made up of
Sieve tube elements and companion cells

Question 11

Sieve tube elements

Answer 11

Lined end to end
No nucleus no cytoplasm 
Perforated sieve plates
Perforations allow movement of sap 
Sieve tubes very thin walls and usually five or six sided

Question 12

Companion cells

Answer 12

Large nucleus and dense cytoplasm

Numerous mitochondria to produce ATP needed for the active processes needed to load assimilate actively into sieve tubes

Question 13

Pathways of water

Answer 13

Water can pass through cellulose molecules in cell e the wall
Many plants housetrained by cytoplasmic bridges with plasmodesmata joining cytoplasms

Question 14

Three pathways

Answer 14

Apoplast
Symplast
Vacuolar

Question 15

Apoplast

Answer 15

Spaces in cells and between the cells

Mass flow not osmosis
Dissolved mineral ions and salts can be carried in the water

Question 16

Symplast

Answer 16

Cytoplasm through the plasma membrane and then passes through the. Plasmodesmata to next cytoplasm

Question 17

Vacuolar

Answer 17

Same as symplast but water can enter that vacuoles also

Question 18

Pathway of water leaving the leaf

Answer 18

Xylem to leaf
Osmosis to spongy mesophyll and also apoplast pathway
Water evaporates from the walls are spongy Mesophyll
Water defuses out leave by open stomata
Movement dependent on the water vapour potential gradient

Question 19

Transpiration stream important because

Answer 19

Transports useful mineral ions up plant
Maintained so turgidity
Supplies water for growth so elongation and photosynthesis
Supplies that water that can evaporate and keep plant cool and hot day

Question 20

Factors affecting transpiration

Answer 20

Light intensity
Temperature
Relative humidity 
Air movement 
Water availability

Question 21

Water uptake across roots

Answer 21

Root hair cell - water and minerals
Down the water potential gradient to endodermis of the vascular bundle
Apoplast pathway to endodermis and then Casparian strip blocks so symplast pathway used

Question 22

Casparian strip ensures

Answer 22

Water and dissolved minerals have to pass the cell cytoplasm through plasma membranes
Plasma membrane contains transporter proteins which actively pump mineral ions from the cytoplasm of the cortex house into the medulla and xylem.
So water potential of Majilla more negative so water moves into them by osmosis
Water can’t pass back into the cortex after entering medulla as endodermal cells is blocked by Casparian strip

Question 23

3 things that help movement of water up stem

Answer 23

Root pressure - medulla water pressure builds up and forces water into xylem
Transpiration pull - cohesion tension theory - water lost at the top of Column
Capillary action - adhesion can pull water against side of vessel