Mass Transport In Plants

Question 1

Why do plants need a specialised exchange system

Answer 1

They have a low surface area to volume ratio
Can’t rely on diffusion alone

Question 2

What is transpiration

Answer 2

The loss of water vapour from the stomata by evaporation

Question 3

What four things effect the rate of transpiration

Answer 3

Light
Temperature
Humidity
Wind

Question 4

Relationship between light and transpiration + why

Answer 4

More light more stomata open = larger surface area for evaporation

Question 5

Relationship between temperature and transpiration

Answer 5

More heat means more kinetic energy so more evaporation

Question 6

Relationship humidity and transpiration

Answer 6

More water vapour in the air will make the water potential more positive outside the leaf so reduces the water potential gradient less transpiration

Question 7

Relationship between wind and transpiration

Answer 7

More wind will blow away humid air that has water vapour and therefore maintains the water potential gradient

Question 8

What is cohesion

Answer 8

When water molecules stick together

Question 9

What is adhesion

Answer 9

When water stick to other molecules

Question 10

What 3 tings make it possible for the xylem to transport water all the way from the roots

Answer 10

Cohesion
Adhesion in capillary
Root pressure

Question 11

Why does cohesion help is xylem

Answer 11

Water sticks as a column so is easier to be transported

Question 12

The narrower/wider the xylem the impact of capillarity (adhesion)

Answer 12

Narrower

Question 13

Explain root pressure + why helps water transportation

Answer 13

As water move in root increase volume of liquid in root so increases pressure
Increase pressure forces water upwards

Question 14

What does the phloem transport

Answer 14

Organic substances

Question 15

What two cells does the phloem contain

Answer 15

Sieve tube
Companion cells

Question 16

Features of side tube elements in phloem

Answer 16

Living cells
No nucleus
Few organelle

Question 17

What is the role of the companion cell

Answer 17

Provides ATP for active transport

Question 18

What is translocation

Answer 18

The movement of sugars from the source(s) to the sink(s)

Question 19

What is the growth tissue in plants called

Answer 19

Meristem

Question 20

Explain why water moves up the stalk of plants

Answer 20

Water evaporates from leaves through stomata
Water potential gradient pulls up the water and osmosis creates tension
Cohesion maintains the column of water

Question 21

When anomalies are present which average should you use
Mean
Mode or median

Answer 21

Median

Question 22

How to use a scalpel correctly

Answer 22

Cut away from yourself
On a non-slip surface

Question 23

Why can an organism exchange directly with its environment

Answer 23

SHORT DIFFUSION PATHWAY

Question 24

The rate of water movement through the shoot in a photometer may not be the same as the rate of water movements through the shoots of a whole plant why

Answer 24

Plant had roots

Question 25

Why do we need control variable

Answer 25

To make results comparable

Question 26

How does increase in temperature allow more pigment out

Answer 26

Damage to cell membrane
Proteins denature
Increases fluidity of phospholipid bilayer

Question 27

Explain how to achieve a calibration curve

Answer 27

Produce know concentration of X
Measure absorbency at each concentration
Plot a graph of absorbance on the y-axis and concentration on the x-axis and draw a curve
Use absorbance of sample to find protein concentration from curve

Question 28

Why is less transpiration an advantage

Answer 28

More water available for photosynthesis

Question 29

Why is it bad if oxygen does not reach respiring cells

Answer 29

Not enough oxygen for aerobic respiration

Question 30

Describe cohesion-tension theory of water transport

Answer 30

Water lost from leaf because of transpiration
Lowers water potential of leaf cells
Water pulled up xylem creating tension
Water molecules cohesion creating column of water
Adhesion between water molecules and walls of xylem