Water & Sugar Transport (4)

Question 1

What is a plant?

Answer 1

= a bundle of tubes with its base embedded in the ground.

Question 2

Through what process does water movement occur? & How?

Answer 2

Osmosis due to root pressure.

Question 3

From the … to the … water moves via osmosis?

Answer 3

From the …ground.. to the ..roots.. moves via osmosis.

Question 4

Through what “force” does water travel from the roots?

Answer 4

Capillary action.

Question 5

What is capillary action facilitated by when assisting water to move upwards from the roots?

Answer 5

Electric charge.

Question 6

What role does transpiration play in water transport?

Answer 6

It allows water to reach the top parts of tall plants.

Question 7

What helps transpiration in enabling water to reach the top parts of tall plants?

Answer 7

Evaporation.

Question 8

Through what/what manner does water move from the roots to the leaves?

Answer 8

Via a single column.

Question 9

What allows the column of water to reach heights exceeding 90m?

Answer 9

Cohesion tension.

Question 10

What facilitates the whole process of water transport?

Answer 10

Atmospheric pressure.

Question 11

Lay out the water movement process generally.

Answer 11

Water moves from ground to roots (osmosis).
|
Water then moves from roots to leaves through a single column (capillary action + cohesion & adhesion).
|
Water exits leaves into the atmosphere via stomata (transpiration + evaporation).

Question 12

How does water absorption by the roots occur?

Answer 12

Water & mineral uptake occurs via the root hairs through diffusion of this water & minerals.

Question 13

Function of root hairs?

Answer 13

Increase SA.

Question 14

Which part of roots are the least impermeable?

Answer 14

Mature regions of the root.

Question 15

What are the 3 main pathways for water & mineral absorption via the roots?

Answer 15

• Apoplast.
• Symplast.
• Transmembrane.

Question 16

Describe each pathway?

Answer 16

● Apoplast
= via cell wall intracellular spaces.

● Symplast
= via entire cell network.

● Transmembrane
= via cell membrane & tonoplast.

Question 17

What produces/generates root pressure?

Answer 17

Solute accumulation in the xylem.

Question 18

Why is root pressure generated?

Answer 18

Due to the decrease in osmotic & water potential of the xylem. Therefore, a combination of these forces leads to a positive pressure in the xylem.

Question 19

Root pressure value?

Answer 19

0.2 MPa.

Question 20

What is the xylem in the context of water transport?

Answer 20

= the longest part of the water pathway through the plant.

Question 21

Name & state what happens to the 2 transport cells which are also xylem types?

Answer 21

Tracheids & Vessel elements
- they’re both dead at maturity & remain as hollow tubes.

Question 22

How does water move in the xylem? (2)

Answer 22

• Bulk flow.
• Driven pressure.

Question 23

What is bulk flow?

Answer 23

= movement of fluid driven by pressure (differences in pressure potential) that moves the entire solution much faster.

Question 24

Water moves through xylem with …?

Answer 24

Low resistance.

Question 25

What is water potential?

Answer 25

= potential of an area to possess water.

Question 26

Cohesion-tension model/Cohesion-adhesion model?

Answer 26

= explains how water gets transported up the tree.

Question 27

What is the cohesion-adhesion of xylem dependent on?

Answer 27

Properties of water.

Question 28

Cohesion?

Answer 28

= the tendency of water to cling together.

Question 29

Why does water cling together?

Answer 29

Because of the H-bonds thus causing the formation of a continuous column of water.

Question 30

Adhesion?

Answer 30

= the ability of water to interact with the wall of xylem.

Question 31

Why is water able to interact with the wall of xylem?

Answer 31

Because water is slightly polar in nature.

Question 32

How does adhesion advantage the water column? (2)

Answer 32

• Strengthens water column.
• Prevents water from slipping down.

Question 33

Cohesion = … + … ?

Answer 33

Cohesion = Water + Water.

Question 34

Adhesion = … + … ?

Answer 34

Adhesion = Water + Cell wall.

Question 35

What is transpiration?

Answer 35

= process where water is carried through plants from roots to the stomata of leaves & released into the atmosphere.

Question 36

Transpiration = ?

Answer 36

the driving force that pulls water from shoots to the root.

Question 37

How does transpiration pull water from shoots to roots? Explain (2).

Answer 37

• It applies tension that draws water column first in the leaves then down the stem & roots.

• Water molecules that are lost then get replaced by other molecules from leaf veins.

Question 38

What are stomata?

Answer 38

= small pores in the leaf epidermis.

Question 39

What do stomata do? / Function?

Answer 39

They open & close to control the transpiration rate in plants.

Question 40

Explain stomata procedure. What happens? (4)

Answer 40

• Pores are boarded by 2 guard cells.

• Stomata opens when water enters guard cells & closes when water exits guard cells.

• Active transport of K+ ions causes water to flow via osmosis.

• Stomata open.

Question 41

Through what organ does sugar transport occur?

Answer 41

Phloem.

Question 42

What are the 2 components of phloem?

Answer 42

• Sieve tubes.
• Companion cells.

Question 43

Pressure-flow model?

Answer 43

= states that leaves are the source of the sugar that’s actually transported by the phloem.

Question 44

What directions do water & sugar(organic molecules) move in respectively?

Answer 44

● Water
= unidirectional.

● Sugar/organic molecules
= multi directional.

Question 45

Differences between transpiration & translocation? (5)

Answer 45

● passive × active.

● water+minerals × sucrose+aa+hormones [WHAT DOES IT TRANSPORT?]

● tracheids+vessel elements × sieve tubes+companion cells [COMPONENTS]

● dead × alive [STATE AT FUNCTIONAL MATURITY]

● moves water+minerals from roots to shoot × moves organic molecules from source (leaves/storage organ) to the sink [DIRECTION OF TRAVEL]