Movement of substances in and out of cells

Question 1

diffusion

Answer 1

net random movement of substances from an area of high to low concentration

Question 2

osmosis

Answer 2

net random movement of water from an area of high to low water potential across a partially permeable membrane

Question 3

active transport

Answer 3

movement of substances from an area of low to high concentration, using energy from ATP

Question 4

What is the function of the transport system in plants?

Answer 4

leaves can receive water and
mineral ions, both for photosynthesis

Question 5

What is the xylem?

Answer 5

tissue that transports water and mineral ions from the roots to the leaves

Question 6

Describe the structure of the xylem

Answer 6

• made of thick walled dead cells without any cytoplasm
• cell wall with lignin
• upwards movement
• no end walls

Question 7

Why doesn’t the xylem have organelles?

Answer 7

to prevent obstruction to flow of water and minerals

Question 8

Why does the xylem have cell walls stiffened with lignin?

Answer 8

waterproof
strength
stops cell collapsing in

Question 9

Why doesn’t the xylem have end walls?

Answer 9

cells join together form long tubes to make complete tissue

Question 10

Give examples of mineral ions needed for photosynthesis

Answer 10

magnesium ions
nitrate ions

Question 11

What is the use of magnesium ions in plants?

Answer 11

make chlorophyll for photosynthesis

Question 12

What is the use of nitrate ions in plants?

Answer 12

make amino acids and proteins

Question 13

What is the phloem?

Answer 13

tissue in plants that transports sugars and amino acids both up and down the plant from the leaves to respiring tissues

Question 14

translocation

Answer 14

movement of sugars and amino acids through the phloem that uses energy

Question 15

Describe the structure of the phloem

Answer 15

• companion cells
• sieve plates (thin layer of cytoplasm)
• cell walls of cellulose

Question 16

Why does the phloem have companion cells?

Answer 16

keeps phloem alive
has ribosomes and cytoplasm to do this

Question 17

Why does the phloem have sieve plates?

Answer 17

allows contents to flow through

Question 18

How does translocation work?

Answer 18

• companion cells have mitochondria
• sucrose moved into sieve tubes by active transport
• low water potential in sieve tubes
• water moves via osmosis into sieve tubes
• high pressure created
• sucrose and water removed from phloem

Question 19

Why is translocation called an active process?

Answer 19

energy needed

Question 20

Why is the process of translocation so important?

Answer 20

sugars needed in growing points
- roots
- leaves

Question 21

How is water transported around the plant?

Answer 21

• enters by root hair cells
• high surface areas
• short diffusion distance
• water potential outside plant is higher than inside cells
• via osmosis
• water moves from cell to cell down concentration gradient
• via osmosis
• water reaches xylem vessel - carried to all parts of plant

Question 22

How are mineral ions transported around the plant?

Answer 22

• enters by root hair cells
• concentration of the solutes outside is lower than inside
• move into the roots from the soil
• via active transport
• reaches phloem vessel
• carried to all part of plant

Question 23

Which direction does the water and mineral ions move in the xylem?

Answer 23

upwards towards leaves

Question 24

Which direction do the amino acids and proteins move in the phloem?

Answer 24

upwards and downwards to leaves and roots

Question 25

transpiration

Answer 25

water loss via evaporation through the stomata

Question 26

What is the transpiration stream?

Answer 26

upwards movement of water through the xylem from roots to leaves

Question 27

What are the functions of the transpiration stream?

Answer 27

- carry mineral ions - keep turgor pressure high - supplies water - evaporation cools leaf

Question 28

Describe the process of transpiration

Answer 28

- water leaves cells of the mesophyll - evaporates into air spaces in spongy mesophyll - water diffuses out through stomata - loss of water from mesophyll cells makes lower water potential - water moves into them by osmosis - water leaves xylem to replace water lost

Question 29

How does temperature affect transpiration?

Answer 29

- increase in kinetic energy - faster rate at higher temps - more transpiration

Question 30

How does light intensity affect transpiration?

Answer 30

- more light - more photosynthesis - more co2 needed - stomata open - more transpiration

Question 31

How does wind speed affect transpiration?

Answer 31

- water molecules blown away faster - higher water potential in leaf - more transpiration

Question 32

How does humidity affect transpiration?

Answer 32

transpiration increases when humidity decreases due to concentration gradient

Question 33

How does water supply affect transpiration?

Answer 33

lower water supply is caused by more transpiration than supply - plant wilts - guard cells around stomata become turgid - stops transpiration

Question 34

What is an isotonic solution?

Answer 34

solution outside cell has same water potential as inside cell - no net movement

Question 35

What is a hypertonic solution?

Answer 35

solution outside cell has lower water potential then inside cell - net movement of water molecules out of cell

Question 36

What is a hypotonic solution?

Answer 36

solution outside cell has higher water potential then inside cell - net movement of water molecules into cell

Question 37

What happens to an animal cell in an hypotonic solution?

Answer 37

lysed bursts - no cell wall

Question 38

What happens to plant cell in an hypotonic solution?

Answer 38

turgid (normal)

Question 39

What happens to an animal cell in an isotonic solution?

Answer 39

normal

Question 40

What happens to a plant cell in an isotonic solution?

Answer 40

flaccid

Question 41

What happens to an animal cell in an hypertonic solution?

Answer 41

shrivels

Question 42

What happens to a plant cell in an hypertonic solution?

Answer 42

plasmolyzed wilts - not enough water to fill cells - cytoplasm shrinks

Question 43

What are the stomata?

Answer 43

holes in the surface of the leaf, mainly on bottom

Question 44

What is the function of the stomata?

Answer 44

gas exchange CO2 in (photosynthesis) O2 out (respiration)

Question 45

What is the function of the guard cells in relation to stomata?

Answer 45

control the opening and closing of stomata two guard cells on either side of a stomata

Question 46

Describe the structure of a guard cell

Answer 46

thickened, inflexible inner cell wall

Question 47

How do guard cells complete the function in relation to stomata?

Answer 47

- photosynthesise in light - concentration of sugars increases - water potential in guard cells lowers - water moves into guard cells - via osmosis - become turgid and stomata open (opposite to close ; dark etc.)

Question 48

What is a potometer?

Answer 48

device used to measure rate of transpiration

Question 49

How do you set up a potometer?

Answer 49

- cut stem of shoot - put shoot stem into bung - put bung into potometer - make sure tap is closed and is full of water (no bubbles) - lift potometer out of water - leave end of capillary tube out of water until air bubble forms then put end into beaker of water - measure transpiration rate as distance bubble travels in five minutes

Question 50

What are some things to ensure when setting up a potometer?

Answer 50

- potometer set up under water - prevents air bubbles from entering system and blocking xylem - grease joint with petroleum jelly - this prevents water loss and air entry - take multiple readings to find average

Question 51

Define translocation

Answer 51

movement of dissolved substances such as sucrose and amino acids, down the phloem towards the roots