3.6 Mass Transport in Plants

Question 1

What is cohesion?

Answer 1

Water molecules sticking to each other using H bonding to form a continuous column

Question 2

What is adhesion?

Answer 2

Water molecules sticking to the walls of the xylem

Question 3

What is tension?

Answer 3

Water moves into the cells of the leaf by osmosis creating a negative pressure inside the xylem

Question 4

Why does water move into the cells of the leaf from the xylem?

Answer 4

As water evaporates out of the stomata the cells of the leaf are losing water creating a lower water potential

Question 5

What is the transpiration stream?

Answer 5

Water moves into the root hair cells by osmosis, up the xylem and into the cells of the leaf

Question 6

What is transpiration?

Answer 6

Water evaporating out of the stomata

Question 7

How does light intensity impact transpiration?

Answer 7

Higher light intensity opens more stomata so more water evaporates

Question 8

How does temperature impact transpiration?

Answer 8

Higher temperature provides more energy so evaporation is faster

Question 9

How does wind speed impact transpiration?

Answer 9

Wind moves water vapour away from stomata so transpiration is faster

Question 10

How does humidity impact transpiration?

Answer 10

If there is more water surrounding the stomata transpiration is slower

Question 11

Why is the trunk of a tree narrowest at midday?

Answer 11

Most transpiration so adhesion is at its strongest

Question 12

How are xylem vessels adapted to withstand adhesion?

Answer 12

Lignin makes them strong to withstand force from water

Question 13

What property of water allows cohesion?

Answer 13

Polarity

Question 14

What is a potometer?

Answer 14

A piece of equipment allows the measurement of the rate of transpiration

Question 15

What is the source in reference to a plants glucose?

Answer 15

Where glucose is produced in photosynthesis - the leaves

Question 16

What is the sink in reference to a plants glucose?

Answer 16

Where glucose is needed for respiration - the roots

Question 17

What is the role of the sieve tube elements?

Answer 17

Cells that allow transport of molecules from source to sink

Question 18

What is the role of companion cells?

Answer 18

Provide energy for active transport

Question 19

How are the sieve tube elements adapted to allow movement of substances?

Answer 19

Few organelles = hollow
Perforated ends = substances can move through

Question 20

How is sucrose moved into sieve tube elements?

Answer 20

Active transport

Question 21

What is glucose converted into for transportation?

Answer 21

Sucrose

Question 22

Which cells do respiration to release energy for active transport?

Answer 22

Companion cells as they have many mitochondria

Question 23

Where does water move into the phloem from?

Answer 23

From the xylem

Question 24

How does water moving into the phloem effect hydrostatic pressure?

Answer 24

Increases it

Question 25

What direction is the movement caused by the hydrostatic pressure caused by water movement into the phloem?

Answer 25

Downwards towards the roots

Question 26

What happens to sucrose once it is in the roots?

Answer 26

Used in respiration or stored for later use

Question 27

What happens to water once it is in the roots?

Answer 27

Moves into xylem by osmosis

Question 28

What is done for a ringing experiment?

Answer 28

A chunk of stem cut out containing phloem

Question 29

Describe the expected results of the ringing experiment.

Answer 29

Bulge above missing chunk containing sucrose dissolved in fluid

Question 30

What does a radioactive marker on carbon show?

Answer 30

Movement of glucose from source to sink

Question 31

Why can insects passively drink from phloem?

Answer 31

Fluid is high pressure