mass transpoort in plants

Question 1

what are all the parts of the leaf

Answer 1

cuticle

stomata

veins

xylem

phloem

upper epidermis

palisade mesophyll

spongy mesophyll

lower epidermis

Question 2

how is water absorbed

Answer 2

via root hair cells by osmosis as the xylem has a low water potential at the start

Question 3

what happens when the water reaches the xylem

Answer 3

it is transported against gravity along its long thick-walled tubes

Question 4

what exactly is transpiration

Answer 4

evaporation of water vapour through stomata

Question 5

what is the first step of the cohesion tension theory

Answer 5

water is bipolar so hydrogen bonds are formed between molecules (cohesion)

Question 6

what is the second step of the cohesion tension theory

Answer 6

this results in a continuous water column being created in the xylem

Question 7

what is the third step of the cohesion tension theory

Answer 7

water evaporates out of the stoma,so the column is pulled up the xylem (transpirational pull)

Question 8

what is it called when the column is pulled up the xylem

Answer 8

a transpirational pull

Question 9

what is the fourth step of the cohesion tension theory

Answer 9

this puts tension on the xylem making its diametre increase

Question 10

how can a xylem form a column

Answer 10

xylem cells are hollow because theyre dead

xylem cells have no end walls so a column can form

Question 11

what does the phloem do

Answer 11

transport organic substances via translocation

Question 12

where does the mass flow hypothesis take place

Answer 12

the phloem

Question 13

what are all the components of the phloem

Answer 13

sieve tube element

lateral sieve area

sieve tube palate

Question 14

what is the first step of the mass flow hypothesis

Answer 14

organic molecules e.g. sucrose are created by photosynthesis and are transported to the companion cells by facilitated

Question 15

what is the second step of the mass flow hypothesis

Answer 15

sucrose is actively transported into the phloem/sieve tube elements by co-transport with hydrogens ions

Question 16

what is the third step of the mass flow hypothesis

Answer 16

this decreases water potential,so water enters the phloem from the xylem by osmosis

Question 17

what is the fourth step of the mass flow hypothesis

Answer 17

this increases volume,increasing hydrostatic pressure

Question 18

what is the fifth step of the mass flow hypothesis

Answer 18

sugars used in respiring cells,increasing water potential,so sugars exit by osmosis,decreasing hydrostatoc pressure

Question 19

what is the sixth step of the mass flow hypothesis

Answer 19

a hydrostatic oressure gradient is therefore created from the phloem to respiring cells