transport in plants

Question 1

what is the function of the xylem

Answer 1

transport water and minerals from the roots to the leaves

Question 2

what is the function of the phloem

Answer 2

to transport sucrose and amino acids made by the plant through photosynthesis to photosynthesising regions in the roots and stem

Question 3

what are root hair cells

Answer 3

single celled extensions of epidermis cells

Question 4

what is the journey of water from the soil to the plant

Answer 4

soil -> root hair cell -> root cortex -> xylem vessel -> mesophyll cells

Question 5

what is transpiration

Answer 5

Transpiration is the loss of water vapour from plant leaves by evaporation of water at the surfaces of the mesophyll cells followed by diffusion of water vapour through the stomata.

Question 6

how is lost water recollected

Answer 6

Water travels up xylem from the roots into the leaves of the plant to replace the water that has been lost due to transpiration

Question 7

how does transpiration occur

Answer 7

• Evaporation takes place from the surfaces of spongy mesophyll cells
• The many interconnecting air spaces between these cells and the stomata creates a large surface area
• This means evaporation can happen rapidly when stomata are open

Question 8

how is the transpiration stream created

Answer 8

Water molecules are attracted to each other by cohesion - creating a continuous column of water up the plant
Water moves through the xylem vessels in a continuous transpiration stream from roots to leaves
Transpiration produces a tension or ‘pull’ on the water in the xylem vessels by the leaves
As water molecules are held together by cohesive forces (each individual molecule ‘pulls’ on the one below it), so water is pulled up through the plant
If the rate of transpiration from the leaves increases, water molecules are pulled up the xylem vessels quicker

Question 9

what is cohesion force

Answer 9

force of attraction between molecules

Question 10

what is wilting

Answer 10

If more water evaporates from the leaves of a plant than is available in the soil to move into the root by osmosis, then wilting will occur
This is when all the cells of the plant are not full of water, so the strength of the cell walls cannot support the plant and it starts to collapse

Question 11

how does temperature affect rate of transpiration

Answer 11

increases with temprature

Question 12

why does temperature increase rate of transpiration

Answer 12

as water evaporates more rapidly at higher temperatures

Question 13

how does humidity affect rate of transpiration

Answer 13

as humidity increases rate of transpiration decreases

Question 14

why does humidity decrease rate of transpiration

Answer 14

as the atmosphere/air around the plant will be having more water in it, the concentration gradient of water inside the plant and in the atmosphere is stopped, therefore water wont diffuse out of the plant as fast.

Question 15

what does turgidity mean

how does it occur

Answer 15

the fact of being swollen or firm, usually because of being full of liquid: Water is essential to maintain the turgidity of cells. Cell membrane pushes up against cell wall

Question 16

what is a flaccid cell

Answer 16

Flaccid corresponds to a cell lacking turgidity. cells are floppy and/or loose, and cells have drawn in and pulled away from the cell wall.

Question 17

what is an isotonic solution

Answer 17

Isotonic solutions contain equal concentrations of impermeable solutes on either side of the membrane and so the cell neither swells nor shrinks.

Question 18

what is a hypotonic solution

Answer 18

A hypotonic solution is one in which the concentration of solutes is greater inside the cell than outside of it.
solution has more water than the cell

Question 19

what is a hypertonic solution

Answer 19

A hypertonic solution is one in which the concentration of the solute is higher outside the cell compared to inside the cell.

solution has less water than the cell

water will leave the cell leaving it flaccid

Question 20

what happens to a cell which is placed in a isotonic solution

Answer 20

no change

Question 21

what happens to a cell which is placed in a hypertonic solution

Answer 21

the cell becomes flaccid, as the water inside the cell is more dilute than the water outside, causing the water to flow down the potential gradient through a partially permeable membrane

Question 22

what happens to a cell which is placed in a hypotonic solution

Answer 22

the cell becomes turgid as the solute is more dilute than the cell, causing the water to move down the potential gradient through a partially permeable membrane

Question 23

what does concentration mean

Answer 23

the solute will have less water

Question 24

what does dilute mean

Answer 24

the solute will have more water

Question 25

where is the xylem

Answer 25

inside

Question 26

where is the phloem

Answer 26

outside

Question 27

what is translocation

Answer 27

The transport of sucrose and amino acids in the phloem, from regions of production to regions of storage or use.

Question 28

what is the place food in the plant is made called

Answer 28

source

Question 29

what is the place food in the plant reaches called

Answer 29

sink

Question 30

how does the winter affect how the phloem transports food

Answer 30

During winter, when many plants have no leaves, the phloem tubes may transport dissolved sucrose and amino acids from the storage organs to other parts of the plant so that respiration can continue

Question 31

how does the summer affect how the phloem transports food

Answer 31

the plant has grown, the leaves are photosynthesizing and producing large quantities of sugars; so they become the source and the roots become the sinks – storing sucrose as starch until it is needed again

Question 32

how does the “growth period” affect how the phloem transports food

Answer 32

the storage organs (eg roots) would be the source and the many growing areas of the plant would be the sinks

Question 33

aphids feed on the contents of the phloem tubes

what type of food is lacking in their diet

Answer 33

fat

Question 34

what are the guard cells function

Answer 34

to open and close stomata

Question 35

what are some adaptation of leaves for photosynthesis

Answer 35

thin, to reduce the diffusion distance

large surface area to absorb maximum sunlight

Question 36

what is the order of the specific organs in the plant

Answer 36

waxy cuticle
upper epidermis
palisade mesophyll
spongy mesophyll-vascular bundle on same level
lower epidermis-guard cell with chloroplasts
stomata

Question 37

water not lost in transpiration is used for what

Answer 37

photosynthesis
turgidity

Question 38

explain how transpiration is responsible for the movement of water in the xylem

Answer 38

loss of water vapour through stomata in leaves
evaporation from surfaces of mesophyll cells into air spaces
loss of water from leaf cells lowers water potential
water moves into leafs from xylem
this pulls on water by cohesion forces and pulls water to the leaf cells

Question 39

state three structural adaptations of plants living in hot dry environments

Answer 39

few stomata
hairs on the leaves
small leaf surface area

Question 40

features of epidermis and its adaptation for photosynthesis

Answer 40

guard cells —– allows gas to enter/leave
thin/flat —– allows more light to pass through
no chloroplasts —– allows light to pass through

Question 41

features of pallisade mesophyll cells and its adaptation for photosynthesis

Answer 41

contains many chloroplasts — traps light energy
air spaces —- for diffusion/ movement of gasses
tightly packed —– maximise light received

Question 42

describe the pathway taken by co2 when entering a leaf to the spongy mesophyll cells

Answer 42

passes through stomata
moves through intracellular air spaces