Gas exchange

Question 1

gas exchange method in single celled organisms

Answer 1

simple diffusion

Question 2

simple diffusion in single celled organisms

Answer 2

large SA:vol ratio

O2 can diffuse into cells, CO2 can diffuse out of cells via surface membrane

Question 3

sphere volume equation

Answer 3

4/3 X 3.14 X r3

Question 4

sphere SA equation

Answer 4

4 X 3.14 X r2

Question 5

insect gas exchange adaptations

Answer 5

• waterproofing-exoskeleton w waxy cuticle
• small SA:vol ratio-small area to lose water
• diffusion gradient-O2 used at tissue so more diffuses in high CO2 at tissue so moves toward trachea+ out
• ventilation-rhythmic abdominal movements, mass movement of air in+out, speed exchange
• spiracles-lose water open, close till gas exchange(CO2),control via valve

Question 6

why must insects be small

Answer 6

to maintain diffusion gradient from surroundings to body tissue, limited by atmospheric O2 conc

Question 7

insect respiratory system components

Answer 7

spiracle
trachea
tracheole
cell

Question 8

fish respiratory system components

Answer 8

lamella
gill filaments
artery

Question 9

fish gill adaptations

Answer 9

thin epithelium
counter current system
increased SA

Question 10

thin epithelium advantage in fish

Answer 10

short diffusion pathway

Question 11

why do fish need gas exchange adaptations

Answer 11

oxygen concentration lower in water than air

Question 12

large SA advantage in fish

Answer 12

lamella-many capillaries, thin surface cell layer

gill filaments-large SA for gas exchange to occur over

Question 13

counter current system

Answer 13

blood flows through lamellae one direction, water flows over them in opposite direction
-high O2 conc water always next to lower O2 conc blood
steep conc gradient maintained

Question 14

what are dicotyledonous plants

Answer 14

flowering plants w broad leaves

Question 15

gas exchange surface in dicotyledonous plants

Answer 15

mesophyll cells-well adapted large SA

Question 16

dicotyledonous plants components

Answer 16

guard cell
stomata
mesophyll

Question 17

guard cell open/close

Answer 17

open for gas exchange

close to retain water

Question 18

when is external air needed dicotyledonous plants

Answer 18

if no balance between photosynthesis(waste product O2) and respiration (waste product CO2)

Question 19

dicotyledonous plant adaptations

Answer 19

large SA:vol ratio
simple diffusion of gas through plant
stomata on bottom of leaves-less evaporation, shade

Question 20

most diffusion in dicotyledonous leaves as

Answer 20

thin+flat-large sA
lower epidermis has stomata
many air spaces in mesophyll layer

Question 21

what are xerophytic plants

Answer 21

plants adapted to living in areas with a short supply of water

Question 22

adaptations of xerophytic plants

Answer 22

sunken stomata
hairs on leaves
rolled leaves
thick waxy cuticle

Question 23

rolled leaves

Answer 23

trap air with high water potential in leaf
no water loss as no water potential gradient between leaf inside/outside
reduced water loss

Question 24

hairy leaves

Answer 24

trap moist air next to leaf surface(water vapour)

reduce water potential gradient between inside/outside of leaf so less water is lost

Question 25

waxy cuticle

Answer 25

prevent water evaporation(as does closing stomata)

Question 26

sunken stomata

Answer 26

traps moist air-reducing water potential gradient

Question 27

smaller organisms

Answer 27

higher SA:vol, high metabolic rate(simple diffusion, not as much needed)

Question 28

larger organisms

Answer 28

low SA:vol, low metabolic rate(use exchange organs, mass transport)

Question 29

human lung components

Answer 29

trachea
bronchus
bronchioles
alveoli

diaphragm, internal/external intercostal muscles

Question 30

alveoli adaptations(specialised exchange surface)

Answer 30

large SA:vol
thin
partially permeable
surrounding + internal medium to maintain diffusion gradient

Question 31

trachea adaptations

Answer 31

cartilage rings add strength+ allow movement

Question 32

inspiration(breathe in)

Answer 32

external intercostal muscles contract
ribs up+ out
diaphragm contract(down, flatten)
-thorax vol increase, air pressure decrease
-air flows in(high outside pressure to low inside pressure)

Question 33

expiration(breathe out)

Answer 33

internal intercostal muscles contract
ribs in +down
diaphragm relax(curve up)
-thorax vol decrease, air pressure increase
-air forced out(high inside pressure to low outside pressure)

Question 34

fricks law

Answer 34

diffusion rate is directly proportional to (SA X conc. difference)/diffusion pathway length