Transport, Storage and Gas Exchange in Flowering Plants

Question 1

autotroph

Answer 1

an organism that makes it own food

Question 2

metabolism

Answer 2

sum of all chemical reactions in an organism

Question 3

transpiration

Answer 3

loss of water vapour from aerial parts of plant by evaporation

Question 4

diffusion

Answer 4

the movement of molecules from a region of high concentration to a region of low concentration

Question 5

osmosis

Answer 5

the movement of water across a semi permeable membrane from a region of high water concentration to a region of low water concentration

Question 6

passive transport

Answer 6

does not require energy

Question 7

why plants need a transport system

Answer 7

to provide materials needed for various plant metabolic processes:

• photosynthesis (co2 taken from atmosphere, water through roots)
• respiration (o2 used from photosynthesis)
• reproduction and growth

materials are transported:

• water
• minerals (nitrates and phosphates by diffusion and active transport)
• carbon dioxide
• carbohydrates

Question 8

leaf adaptations for photosynthesis

Answer 8

flat (large surface area)
large number of chloroplasts present (most in the palisade layer)
contains stomata

Question 9

stomata

Answer 9

what: small pores on undersides of leaves
location: undersides of leaf
function: gas exchange, co2 in, o2 and water vapour out
adaptations/features: large numbers= large surface area for gas exchange

Question 10

epidermis

Answer 10

composed of: dermal tissue

function: protection

Question 11

vascular bundle

Answer 11

composed of: xylem and phloem

function: transport of water, minerals, food

Question 12

ground tissue

Answer 12

function: food storage, photosynthesis

palisade layer: contains more chloroplasts so more photosynthesis occurs here as it is closer to the sunlight

Question 13

guard cells

Answer 13

function: control opening and closing of stomata
how: swell/ become turgid due to high concentration of water, guard cells open, become flaccid, shrink when water is lost, guard cells close

Question 14

sources of carbon dioxide

Answer 14

from the atmosphere, diffuse into stomata

product of respiration

Question 15

how intake of carbon dioxide is controlled

Answer 15

stomata opening and closing
day: open: water vapour out and co2 in when photosynthesis is taking place

night: closed: reducing water loss and co2 intake, photosynthesis not occurring

Question 16

when high levels of co2

Answer 16

stomata close

no more needed for photosynthesis

Question 17

when low levels of co2

Answer 17

stomata open

more needed for photosynthesis

Question 18

why do the stomata sometimes close during the day

Answer 18

if the plant has lost too much water by evaporation

if temperatures are too high

Question 19

by closing stomata plant reduces…

Answer 19

water loss

Question 20

how water enters root hairs to vascular tissue

Answer 20

1. water enters the root hair cells by osmosis- through a selectively permeable membrane
2. cytoplasm of root hair cell has a higher solute concentration than the water in soil
3. water moves from cell to cell by osmosis

Question 21

adaptations of root hairs

Answer 21

walls only one cell thick

large numbers = large surface area for absorption

Question 22

methods of transport through roots

Answer 22

osmosis:
from soil to root hair cells
diffusion:
from root hair cells to root cells (across tissues)

Question 23

how water reaches great heights/upward movement of water

Answer 23

root pressure

transpiration

Question 24

root pressure

Answer 24

build up of water in the root cells creates pressure pushing water upwards

Question 25

transpiration process

Answer 25

1. water evaporates from stomata and diffuses into atmosphere
2. as water diffuses from the leaf it pulls more water out of the leaf
3. osmotic gradient created: lower water concentration in leaves
4. water moves from xylem to leaf cells

Question 26

control of transpiration

Answer 26

why controlled: prevents wilting
how:
1. leaves have a waxy cuticle, water cannot pass through
2. stomata location: lower surface of the leaf where less evaporation occurs
3. guard cells: control shape of stomata, open and close

Question 27

movement of water through the xylem

Answer 27

how: cohesion tension model
what: explains movement of water against the force of gravity
who: henry dixon and john joly

Question 28

explain cohesion tension model

Answer 28

1. cohesion- the sticking of similar molecules to each other, water molecules stick to each other due to hydrogen bonds
2. adhesion - when different molecules stick together, water adheres to walls of xylem
3. cohesive forces stronger than adhesive
4. as each water molecule evaporates (or by transpiration), more water is pulled up through xylem
5. water in the xylem now under tension which ensures water movement, xylem stretches and becomes narrow
6. continuous stream of water is now moving
7. this tension is great enough to pull water to great heights

Question 29

modified storage organs

Answer 29

plant organs that are modified and used to store food as starch/sucrose/cellulose
eg
modified root eg carrot
modified stem eg potato tuber
modified leaf eg onion