exhange and transport systems (plants/insects/fish)

Question 1

what is the purpose of an exoskeleton?

Answer 1

fibrous for protection, lipids prevent water loss

Question 2

what is the tracheal system in insects made from?

Answer 2

trachea, tracheoles, spiracles

Question 3

what are the adaptations of an insect to limit water loss?

Answer 3

small surface area:volume where water evaporates from
waterproof exoskeleton
spiracles can open/close to prevent water loss

Question 4

what happens in the spiracles?

Answer 4

gases can enter and leave

Question 5

what do the trachea have?

Answer 5

rings to strengthen them and keep them open

Question 6

what do the tracheoles do?

Answer 6

extend to tissues to deliver oxygen

Question 7

how does gas exchange occur in insects?

Answer 7

mass transport uses rhythmic and abdominal movements

concentration gradient from tracheoles to atmosphere allows diffusion to occur

Question 8

how does anaerobic respiration occur in insects?

Answer 8

lactase lowers the water potential of cells
water moves in by osmosis from the tracheoles
which decreases the volume of the tracheoles
air is drawn in

Question 9

how can insects control water loss?

Answer 9

close spiracles using muscles
waterproof, waxy cuticle over their body
tiny hairs around spiracles to reduce evaporation

Question 10

what is the role of the epidermis?

Answer 10

limits water loss and controls gas exchange

Question 11

what is the role of the palisade mesophyll?

Answer 11

contains chloroplasts for photosynthesis

Question 12

what is the purpose of the spongy mesophyll?

Answer 12

for gas diffusion to occur

Question 13

what is the role of guard cells?

Answer 13

controls what enters and leaves the plant

Question 14

what is the role of the stomata?

Answer 14

close at night to prevent water loss

Question 15

when are guard cells kept open?

Answer 15

during the day

Question 16

what happens when water enters guard cells?

Answer 16

makes them turgid, which opens the stomatal pore

Question 17

what happens to guard cells if a plant starts to get dehydrated?

Answer 17

guard cells lose water and become flacid, which closes the pore

Question 18

what is a xerophyte?

Answer 18

plant which needs very little water

Question 19

what are examples of xerophytic adaptations?

Answer 19

stomata sunken in pits trap moist air, which reduces the concentration gradeint of water between the leaf and air= less evaporation
hairs on the epidermis to trap moist air around the stomata
curled leaves with the stomata inside- protection from wind which increases evaporation
reduced number of stomata so fewer places for water to escape
waxy, waterproof cuticles on leaves/ stems to reduce evaporation

Question 20

how does water pass through a fish?

Answer 20

fish opens its mouth 
volume of the buccal cavity increases 
pressure increases
water flows in 
fish closes its mouth 
squeezes water out of the buccal cavity 
over the gills and out of the operculum

Question 21

what is the structure of the gill in a fish?

Answer 21

2 piles of soft thin plates- lamellae
attached to bony gill arch
lamellae on top of eachother
kept apart by water

Question 22

what is the role of the afferent artery?

Answer 22

brings deoxygenated blood from the heart

Question 23

what is the role of the efferent artery?

Answer 23

brings oxygenated blood from the gills to the tissues

Question 24

how do fish gills have a large surface area?

Answer 24

gill made of thin plates= gill filaments- large SA for gas exchange
gill filaments covered in lamellae- increase surface area further
lamallae have blood capillaries

Question 25

how does the counter current flow ensure efficent gas exchange?

Answer 25

blood flows through the lamellae and water flows over the lamellae in opposite directions
maintains a large concentration gradient between the water and the blood
concentration of oxygen in water always higher than the blood- so as much oxygen as possible diffuses from the water into the blood