Transport in Plants

Question 1

describe the structure of xylem (6)

Answer 1

dead cells
cell joined end to end
waterproof
hollow
plasmodesmata in walls
one direction flow

Question 2

which tissue has end walls

Answer 2

phloem

Question 3

which tissue has no nucleus

Answer 3

phloem

Question 4

describe the structure of phloem (3)

Answer 4

has companion cells
flows in all direction
sieve elements cells make up tissue

Question 5

purpose of xylem

Answer 5

mechanical support and transport of amino acids and water

Question 6

cells that make up xylem

Answer 6

vessel elements and tracheid, sclerenchyma fibres, parenchyma cells

Question 7

how sieve plate is formed

Answer 7

two sieve elements meet

Question 8

adaptations of the companion cell

Answer 8

high number of mitochondria/ribosomes/plasmodesmata in cell wall
peripheral cytoplasm for less resistance

Question 9

which part of the phloem has the highest concentration of sucrose

Answer 9

sieve element cells

Question 10

describe the process of translocation (7)

Answer 10

H+ ions move out of companion cell by active transport
H+ diffuse back in with sucrose via.facilitated diffusion
through cotransporter protein
sucrose diffuses into sieve tube element by plasmodesmata
water enters by osmosis
hydrostatic pressure builds up
unloads at sink

Question 11

definition of transpiration

Answer 11

the loss of water vapour from leaves to its environment

Question 12

describe the process of transpiration (7)

Answer 12

water diffuses by osmosis from xylem to mesophyll cells
water evaporates from mesophyll cells into air spaces of spongy mesophyll cells
water diffuses out of stomata
water potential reduced
reduces hydrotatic pressure
water pulled by adhesion/cohesion
capillary action

Question 13

high light intensity affects transpiration

Answer 13

stomata opens more = high rate

Question 14

describe apoplastic pathways

Answer 14

movement of water through cell wall by osmosis

Question 15

when does apoplastic pathways normally occur

Answer 15

transpiration rate is high

Question 16

describe symplastic pathways

Answer 16

movement of water through plasmodesmata

Question 17

process when apoplastic pathways reaches endodermis

Answer 17

apoplastic pathway blocked by casparian strip
forced to use symplastic pathways
suberin blocks both ways
passage cell used for symplastic pathway

Question 18

structure of root hair cells (3)

Answer 18

thin permeable cellulose cell wall, more concentrated solution in vacuole, multiple root hair cells

Question 19

describe xerophytes

Answer 19

plants living in environment with short water supply

Question 20

what happens to sucrose in translocation after loading in sink

Answer 20

turns into glucose + fructose
used for storage - starch
used for growth - cellulose
respiration

Question 21

characteristics of xerophytes (4)

Answer 21

sunken stomata
rolled leaves
hairy leaves
thick waterproof cuticle

Question 22

purpose of xerophytes characteristics (4)

Answer 22

steeper gradient
trapping moist air
protection from sun
greater distance for diffusion

Question 23

why do plants require transport systems (4)

Answer 23

distance is too great
cells require substances
respiration
large organisms

Question 24

describe epidermis

Answer 24

thin continuous layer outside the plant

Question 25

function of epidermis

Answer 25

protection
from drying out
prevent infection

Question 26

describe parenchyma cells

Answer 26

thin walled cells used as packing tissue

forms in cortex and pith in stems

Question 27

function of parenchyma cells

Answer 27

storage of starch
support
transport through the cell

Question 28

structure of parenchyma cells (4)

Answer 28

large vacuole
thin wall
spaces between cells
oval shaped

Question 29

function of collenchyma cells

Answer 29

extra cellulose for strengthening

Question 30

describe collenchyma cells

Answer 30

modified version of parenchyma

Question 31

describe endodermis

Answer 31

one cell thick surrounding vascular bundle

Question 32

function of endodermis

Answer 32

selective barrier for roots

Question 33

describe mesophyll cells

Answer 33

made of specialised parenchyma cells

Question 34

function of mesophyll cells

Answer 34

photosynthesis and gas exchange

Question 35

describe pericycle

Answer 35

one to many cells thick in the vascular bundle beside endodermis

Question 36

function of pericycle

Answer 36

new roots can grow

for strength

Question 37

organs of plant

Answer 37

roots, leaves and stems