9)Transport in Plants

Question 1

Why do multicellular plants need transport systems

Answer 1

Need important substances to survive
Get rid of waste substances
Have a small SA : Vol ratio
Diffusion to too slow
Move substances from individual cells quickly

Question 2

What is the 2 types of tissue involved in Transport systems

Answer 2

Xylem
Phloem

Question 3

What is the role of the xylem

Answer 3

Transport water and mineral ions

Question 4

What is the role of the phloem

Answer 4

transport sugars up and down the plant

Question 5

How are xylem vessels adapted for transporting water and minerals

Answer 5

Lonv , tube like
No end walls = uninterupted tube for water

Cells are dead = no cytoplasm

Lignin walls = help support xylem vessels and allow support , prevent collapsing inwards

Pits = water and ions move in and out of the cell.

Question 6

What structures do phloem tubes have

Answer 6

Phloem fibres , parenchyma , sieve tube elements, companion cells

Question 7

How do Sieve tube elements allow transport in the phloem

Answer 7

Living cells

End to end create sieve tubes
allow solutes to pass through
no nucleus , thin cytoplasm

Question 8

How do companion cells allow transport in phloem

Answer 8

lack of nucleus of phloem
Companion cell for every sieve tube element
Carry out function for both structures
Provide enrgy for active transport

Question 9

What is the symplast pathway

Answer 9

Through living parts of the cell - Cytoplasm
Connect through plasmodesmate

Question 10

What is the apoplast pathway

Answer 10

goes through non-living parts - cell walls
Absorbent to==so water can diffuse into them.
Move from high hydrostatic preassure to low hydrostatic pressure

Question 11

From when does the water change path

Answer 11

water gets to the endodermis in the root and reach the casparian strip

Question 12

How does water move up in the plant

Answer 12

Cohesion and tension.
Water evaporates by transpiration
Creates tension / suction which pulls water
Cohesive as they stick together so it creates a column of water.

Adhesion - attracted to the walls and help water to rise up

Question 13

What is transpiration

Answer 13

stomata opens to let carbon dioxide in and water out also .
Gas exchange

Question 14

What are the factors the affect transpiration rate

Answer 14

Light
Temmperature
Humidity
Wind

Question 15

How does Light affect transpiration

Answer 15

The lighter , the faster the rate
Stomata opens when it is light , when it is dark stomata is closed

Question 16

How does Temperature affect ranspiration

Answer 16

Higher temp , faster the rate
More energy so eaporate inside the leaf fast , create a steeper water potential .
Make water diffuse out faster

Question 17

How does humidity affect transpiration rate

Answer 17

Lower humidity , faster transpiration rate
Create a greater water potential gradient

Question 18

How does wind affect transpiration

Answer 18

Windier , faster rate
Lots of movement blows away water molecules. Increase potential gradient

Question 19

How are Xerophytic plants adapted to reduce water loss

Answer 19

Sunken pits - sheltered from the wind

Layers of hair - Traps moist air , reduces potential gradient

Rolled leaves - trap moist air , reduce exposed surface area to wind

Thick waxy layer - reduce water loss and is waterproof

Spines - reduces surface area for water loss

Question 20

How are hydrophilic plants adapted to survive in water

Answer 20

Air spaces - allow plant to float
Large surface area - allow float
Stomata on upper surface - max gas exch
Flexible leaves and stems - prevent damage from water currents

Question 21

What is translocation

Answer 21

Movement of substances ( assimilates ) around the plant
Energy-required
from source to sink

Question 22

Describe mass flow hypothesis

Answer 22

Active transport used to actively load solutes into sieve tube
Lowers water potential inside sieve tube , water enters by osmosis
from xylem and companion cells
Creates high pressure inside at source end
Solutes removed at sink

Question 23

What is active loading

Answer 23

Move substances into the companion cell from surrounding tissues.
Use of co-transporter proteins#
In companion cell - ATP used to actively transport H ions out of celll
Cause a concentration gradient
H bind to co-transporter proteins in companion cell and re-enter cells
Sucrose binds to protein and move into cell