Resource Acquisition And Transport In Vascular Plants

Question 1

What is light capture determined by?

Answer 1

Canopy structure and phyllotaxy

Question 2

Canopy structure

Answer 2

How many leaves are there; more leaves=more light absorbed

Question 3

Phyllotaxy

Answer 3

Arrangement of leaves; no leaves covering each other=more light absorbed

Question 4

What is nutrient acquisition determined by?

Answer 4

Root structure, proliferation of high nutrient zones, and symbiotic associations w/ mycorrhizal fungi

Question 5

Apoplastic route

Answer 5

Moves through matrix of cell walls and intercellular space of cortex; passively moving; not passing through cell membranes

Question 6

Symplastic route

Answer 6

Moves through cells via plasmodesmata

Question 7

Transmembrane route

Answer 7

Combination of apoplastic and symplastic; ions move across membrane to leave cell then transported into another part of cell

Question 8

Casparian strip

Answer 8

Waxy layer that prevents anything from entering via apoplastic route

Question 9

What changes do water and nutrients have to do to reach the vascular cylinder?

Answer 9

Go from apoplastic to symplastic

Question 10

Passive transport

Answer 10

Diffusion across a membrane

Question 11

Active transport

Answer 11

Pumping of solutes across a membrane using ATP

Question 12

Aquaporins

Answer 12

Water channel proteins

Question 13

Osmosis

Answer 13

Determines the net absorption or loss of water by a cell

Question 14

Water potential

Answer 14

A measurement that combines the effects of solute concentration and pressure

Question 15

Transpiration

Answer 15

Evaporation of water from a plants surface; plants lose a large volume of water because of this

Question 16

What replaces the water lost via transpiration?

Answer 16

The water gained by bulk flow called xylem sap

Question 17

How does the sap rise and is it pulled?

Answer 17

Water moves in via roots because they adjust its osmotic potential (-) so water can move in

Xylem tissue cannot adjust b/c dead, but water is being moved up because of the negative pressure caused by a vacuum (created by water being pulled from the top but not being replenished fast enough)

Water moves up to the leaves b/c they modify their water potential by affecting the osmotic component

Water is pulled out of the plant because of the dry air’s high negative pressure

Question 18

Which direction does water flow?

Answer 18

Regions of high water potential to regions of low water potential

Question 19

What unit is water potential?

Answer 19

Megapascals

Question 20

Solute potential

Answer 20

Also called osmotic potential; is proportional to # of dissolved molecules; more solutes=more negative

Question 21

Pressure potential

Answer 21

Physical pressure on a solution

Question 22

What helps move the water up the xylem in the trunk?

Answer 22

Adhesion w/ cell wall and cohesion w/ other water molecules

Question 23

How do guard cells open stoma?

Answer 23

H+ ions are pumped out, K+ ions move in -> low osmotic/solute potential, water moves in; slow process; guard cells are turgid

Question 24

How do guard cells close stoma

Answer 24

H+ pumped in, K+ leaves , higher osmotic/solute potential, water moves in; quicker process; guard cells are flaccid

Question 25

How does wilt happen?

Answer 25

If lost water is not replaced by transport of water

Question 26

Name a reason why transpiration can be good.

Answer 26

Results in evaporative cooling, lowering temp. of plant and preventing denaturing of enzymes

Question 27

Phloem sap

Answer 27

Aqueous solution that is high in sucrose and is transported to a sugar sink via diffusion or bulk transport

Question 28

Sugar source

Answer 28

Organ that is a net producer of sugar like mature leaves

Question 29

Sugar sink

Answer 29

Organ that is a net consumer or storer of sugar, like a bulb or tuber

Question 30

Companion cell

Answer 30

Supports the sieve tube element and transfers/modifies sugars

Question 31

Sieve tube element

Answer 31

Disperses sugar through plant and the sugar is then consumed at sugar sinks

Question 32

How does sap move through a sieve tube?

Answer 32

Sugar is loaded into phloem Since sugar is going into the phloem from the xylem there is a low osmotic potential. This causes phloem to swell. Sugar then leaves phloem into sinks which increase osmotic potential and water moves from phloem back to xylem. Water is recylced