3.3.3 gas exchange

Question 1

what do insects do to get oxygen

Answer 1

they don’t have a respiratory transport system for gas exchange so gases diffuse from air into their cells through their tracheal system

Question 2

adaptations of insects to minimize water loss through spiracles

Answer 2

spiracles close when less oxygen is needed, reducing water loss, waxy exoskeleton is not just impermeable to gases but also water

Question 3

what is a spiracle

Answer 3

small pores which gases enter and leave body of insect in exoskeleton

Question 4

what are the small tubes that carry gases to and from cells in an insect

Answer 4

tracheoles

Question 5

what do tracheoles do

Answer 5

create a larger surface area for diffusion

Question 6

what do fluid filled tips of tracheoles do

Answer 6

gas exchange happens here between end of tracheoles and muscle cells

during activity, fluid moves into muscle cells, for more sa for diffusion

Question 7

what does the muscle tissue do

Answer 7

at rest, muscle cells use up oxygen in respiration which creates a conc gradient
during activity, contraction creates a pressure gradient, forcing air in and out of the

Question 8

process of gas exchange in animals

Answer 8

air moves into trachea via spiracles
oxygen travels down concentration gradient towards the cells
trachea branch off into tracheoles which have thin permeable walls and go directly to individual cells
carbon dioxide form cells moves down concentration gradient towards spiracles to be released into atmosphere
insects use rhythmic ambominal movement to move air in and out of spiracles

Question 9

how are gas exchange surfaces adapted to be efficient

Answer 9

large surface area
short diffusion pathway
large concentration gradient
rich blood supply

Question 10

what is the site of gas exchange in animals

Answer 10

alveoli in lungs

Question 11

single celled organisms are adapted for gas exchange by

Answer 11

thin membrane
partially permeable
large sa:v ratio
short diffusion pathway

Question 12

why are fish unable to have a tracheal gas exchange system

Answer 12

too large

Question 13

what are fish gills made up of

Answer 13

gill filaments and lamella

Question 14

how does lamella create a large surface area

Answer 14

gill filaments are covered in lamella= larger surface area for gas exchange

Question 15

he does many lamella create a rich blood supply

Answer 15

lamella have many capillaries inside and the large amount of lamella means a rich blood supply

Question 16

what does having a rich blood supply allow

Answer 16

maintaining concentration gradient
short diffusion pathway

Question 17

what type of gas exchange system do fish use

Answer 17

counter current system

Question 18

what does counter current mean

Answer 18

blood flows through lamellae , water flows over lamellae in the opposite direction= large concentration gradient between water and blood across the whole lamellae so there is faster gas exchange from water to blood

Question 19

what is the equation for photosynthesis

Answer 19

carbon dioxide + water > oxygen + glucose + energy
6CO2 + 6H2O > C6H12O6 + 6O2 + ATP

Question 20

name layers of a leaf from top to bottom

Answer 20

waxy cuticle
upper epidermis
palisade mesophyll
spongy mesophyll
lowe epidermis
stomata + guard cells
waxy cuticle

Question 21

guard cells and stomata- gas exchange

Answer 21

gas enters and leaves leaf through stomata
opening and closing of stomata is controlled by guard cells
in light, guard cells swell with water= stomata opens
in dark, they shrivel to prevent water loss as stomata closes

Question 22

ways xerophytes (plants that live in extreme environments) are adapted

Answer 22

stomata sunken in pits
layer of hairs on epidermis
curled leaves with stomata inside
reduced number of stomata
waxy cuticle

Question 23

how is the adaptation of xerophytes having their stomata sunken in pits efficient

Answer 23

traps moist air to collect water and reduced concentration gradient

Question 24

how is the adaptation of xerophytes having a layer of hairs on epidermis efficient

Answer 24

trap moisture

Question 25

how is the adaptation of xerophytes having curled leaves with stomata inside efficient

Answer 25

protects from wind
less transpiration

Question 26

how is the adaptation of xerophytes having a reduced number of stomata efficient

Answer 26

reduced water loss

Question 27

how is the adaptation of xerophytes having a waxy cuticle efficient

Answer 27

reduces water loss via evaporation/ transpiration