Transport in Plants Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Potometer

A

used to estimate the transpiration rate
actually measures water uptake by the plant
assumed that uptake is directly related to water loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Radioactive tracer

A

i.e. C14

tracks the movement of organic substances in a plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Ringers

A

if ring of bark (includes phloem, not xylem) is removed from a wood stem, bulge formsabove the ring
fluid from bulge has higher sugar conc. than fluid below - evidence of downward flow of sugars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Aphids

A

aphids used to pierce the phloem to allow sap to flow out

sap flows out quicker nearer leaves than further down stem - evidence of pressure gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Metabolic inhibitor

A

if put into phloem, translocation stops therefore active transport is involved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

OBJECTIONS

A

sugar travels to many sinks, not just to one with highest water potential
sieve plates would create a barrier to mass flow.
lots of pressure required for solutes to get through at a reasonable rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Phloem tissue

A

adapted for transporting solutes
sieve tube elements - living cells that form tube
supported by companion cell, providing the energy required for active transporting solutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Translocation

A

movement of solutes
requires ATP
moves solutes from source to sink (where it’s made to where it’s required)
enzymes maintain conc. grad from source to sink by breaking down solutes constantly (always a conc. grad)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Mass Flow Hypothesis

A

solutes actively transported from companion cells into sieve tubes of phloem at source
water potential lowered
water enters phloem via osmosis from xylem and companion cells
high pressure in sieve tubes at source end of phloem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Mass Flow Hypothesis (2)

A

solutes at sink end used up
water potential less negative inside sieve tubes so water leaves sieve tubes via osmosis
pressure at sink end of phloem decreased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Mass Flow Hypothesis (3)

A

all results in pressure gradient from source to sink end
gradient pushes solutes along sieve tubes towards sink
when they reach sink they’ll be used for respiration or stored i.e. as starch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Xylem

A

long tube structure formed from dead cells (vessel elements) joined from end to end
no end walls meaning uninterrupted tube so water passes through easily

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Cohesion Tension theory

A

water evaporates from leaves at ‘top’ of xylem
creates tension, pulling more water into leaf
cohesion of water molecules means column of water in xylem from leaves to roots moves upwards
water enters the stem through the roots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Transpiration

A

Evaporation of water from a plants surface (especially the leaves)
water evaporates from moist cell walls
accumulates in spaces between cells in leaf
stomata open, water moves out of leaf down conc. grad

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Light and Transpiration

A

lighter = faster transpiration rate

stomata open when light to get more CO2 for photosynthesis. stomata close in the dark

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Temperature and transpiration

A

higher temperature = faster transpiration rate
water molecules have more energy so evaporate from cells faster, increasing conc. grad from leaf to surroundings
diffusion increses

17
Q

Humidity

A

lower humidity = faster transpiration rate

dry air = steep conc. grad = higher transpiration rate

18
Q

Wind

A

windier = faster transpiration rate
air blows water molecules away from around stomata
=increased conc. grad