Multicellularity

Question 1

What is water required for (4)

Answer 1

Photosynthesis
Transport solutes
Cooling of plant
Structural support

Question 2

Macro/micro nutrients needed for growth (3)

Answer 2

Iron (micro) → chlorophyll colour/enzyme/electron transport
Nitrogen (macro) → DNA/ATP/phospholipid
Phosphorus (macro) → small and stunted

Question 3

Definition of water potential

Answer 3

tendency of solution to take up water from pure water through semi permeable membrane

Question 4

Calculate water potential

Answer 4

Water potential = SP + PP

Question 5

HIGH solute potential = ___ water potential

Answer 5

LOW

Question 6

HIGH pressure potential = ___ water potential

Answer 6

HIGH

Question 7

How does turgor pressure affect plant

Answer 7

Low turgor pressure = water moves into cell by osmosis (wilt/flaccid)
High turgor pressure = turgid

Question 8

Direction of water flow

Answer 8

From (+) WP –> (-) WP

Question 9

What is apoplast pathway

Answer 9

Water and solutes pass through cell walls - rapid and unregulated

Question 10

What is symplast pathway

Answer 10

Water pass through plasmodesmata in cytoplasm - slow and regulated

Question 11

Describe the water movement from root to vascular bundle

Answer 11

Water movement through roots by apoplast/symplast pathway
Water and solutes from apoplast → symplast
Water and solutes remain in symplast pathway
Solutes actively pumped into apoplast pathway
Water passively osmosis into apoplast pathway

Question 12

What and where is the casparian strip

Answer 12

Roots in endodermis - blocks apoplast pathway

Question 13

What is xylem made of

Answer 13

Vessel elements

Question 14

Definition of transpiration

Answer 14

Loss of water by evaporation through the leaves

Question 15

Steps of transpiration

Answer 15

During transpiration water diffuses out of the stomata
Water evaporates from mesophyll cell walls
Tension pull apoplast pathway
Pulls water in veins in to turn leaf outwards

Question 16

Transpiration-cohesion-tension mechanism

Answer 16

(T) surface tension in apoplast of mesophyll cells - water pulled by adjacent cells into apoplast = negative pressure moves water out of cell
(C) tension pulls water up passively
(T) tension in stem cause water diffuse by osmosis into roots

Question 17

Rank from lowest to highest water potential (soil/leaf/atmosphere)

Answer 17

soil > leaf > atmosphere

Question 18

What is stomata activity regulated by (4)

Answer 18

light intensity
co2
temperature
water

Question 19

Stomata activity in presence of light

Answer 19

Protons are pumped out
Ions (K+/Cl-) enter 
water enters by osmosis
increase turgor pressure
open pore

Question 20

Stomata activity in presence of NO light

Answer 20

Less active proton pump
K+/Cl- diffuse out passively
Water followed by osmosis
Pressure goes down
pore closes

Question 21

How does light cause changes for stomata activity (light present)

Answer 21

Light activates photoreceptor
Signalling cascade activates proton pump
H+ pumped out of cell
Electrochemical gradient cause K+ in
Symport protein imports CL- and H+

Question 22

Definition of translocation

Answer 22

Movement of carbohydrates/solutes through phloem = translocation

Question 23

When do source and sinks change

Answer 23

Over seasons (carrot)

Question 24

What are the phloem components

Answer 24

Sieve tube element cell
Companion cell
Sieve plate
Plasmodesmata

Question 25

Why does the phloem need companion cell

Answer 25

cell lacks ribosomes/nucleus/golgi/cytoskeleton

Question 26

Describe the mass flow through phloem

Answer 26

Sucrose actively transported from companion cell → sieve tube cell
Sucrose accumulate = WP lowers = high water potential to low water potential movement by osmosis
Increase in pressure
Sucrose active transport into sink cell cause increase in WP in sieve tube element
Water leaves phloem by osmosis

Question 27

What does removing the bark of tree affect

Answer 27

phloem transport