gas exchange

Question 1

what is the name of insects specialised gas exchange system

Answer 1

the tracheal system

Question 2

what are spiracles

Answer 2

• valve openings made of rings of chitin
• helps limit water loss by evaporation

Question 3

what are the tracheoles

Answer 3

thin open ended tubes

Question 4

function of tracheoles

Answer 4

• filled with fluid to help gas dissolving
• penetrate into tissue of insects and speed up gas exchange with tissue

Question 5

describe ventilation in insects

Answer 5

• mechanical process in insects
• insect abdomen moves up and down to change pressure and ventilate the tracheal network
• maintaining a concentration gradient for diffusion

Question 6

what do the network of larger trachea and smaller tracheoles give

Answer 6

a large surface area

Question 7

VENTILATION GRAPH (FLASHCARD)

Question 8

what occurs when insect abdomen moves down

Answer 8

• abdomen moves down
• increase volume, decreases pressure
• spiracles open, air (oxygen) moves into trachea
• carbon dioxide moves out

Question 9

what occurs when insect abdomen moves up

Answer 9

• abdomen moves up
• decrease in volume, increase in pressure
• spiracles close, air(oxygen) moves out of trachea
• O2 conc increases, CO2 conc decreases

Question 10

describe the structure of gas exchange system in fish

Answer 10

• contains gill plate called operculum (acts as a valve)
• contain multiple projections named gill filaments
• filaments contain lamella on them which participate in gas exchange
• blood capillaries flow counter-current to water

Question 11

how do lamalle aid in gas exchange

Answer 11

• allow for a large SA:VOL
• very thin so provide a short diffusion path

Question 12

why are the blood capillaries counter current to water in fish

Answer 12

• maintains a concentration gradient along the entire length of the lamella
• blood leaving gills are almost fully saturated with oxygen

Question 13

why is gas exchange in fish not tidal

Answer 13

lots of energy would be required to push the dense water back out of the mouth

Question 14

ventilation in fish (describe inspiration)

Answer 14

• mouth opens
• operculum closes the opening at the end of the pharynx
• floor of the buccal cavity is lowered
• volume inside the mouth cavity increases, decreasing pressure
• water can flow into the mouth

Question 15

ventilation in fish (describe expiration)

Answer 15

• mouth closes
• floor of buccal cavity is raised
• volume inside the mouth cavity decreases, increasing pressure
• water forces back over the gills
• operculum closes + water flows out

Question 16

how are the leaves of dicotyledonous plants adapted for gas exchange (2)

Answer 16

• contain small pores called stomata, provide a short diffusion distance to cells
• interconnected air-spaces throughout mesophyll tissue provide a large surface area for gas exchange

Question 17

what adaptions do cacti have to limit water loss (5)

Answer 17

• thick cuticle
• small leaf SA:VOL ratio
• stomata sunken in leaves
• deep roots
• widespread shallow roots

Question 18

how does a thick cuticle limit water loss

Answer 18

stops uncontrolled evaporation from leaf cells

Question 19

how does a small leaf SA:VOL ratio limit water loss

Answer 19

reduces SA for evaporation

Question 20

how does stomata sunken in pits limit water loss

Answer 20

maintain humid air around the stomata for a shallower concentration gradient

Question 21

how does deep roots limit water loss

Answer 21

allows access to deep water sources

Question 22

how does widespread shallow roots limit water loss

Answer 22

allows for rapid access to water

Question 23

what adaptions do marram grass have to limit water loss (4)

Answer 23

• thick cuticle
• small leaf SA:VOL ratio
• leaf hairs
• rolled leaves

Question 24

how do leaf hairs and rolled leaves limit water loss

Answer 24

maintain humid air around stomata for a shallower concentration gradient

Question 25

describe components in gross structure of the human gas exchange system

Answer 25

• lungs
• trachea
• bronchi
• bronchioles
• alveoli

Question 26

what are the lungs

Answer 26

highly branched network of tubules ending in many air sacs called alveoli. provide a large SA:VOL ratio for gas exchange

Question 27

what is the trachea

Answer 27

flexible airway supported by rings of cartilage to prevent collapse

Question 28

what are the bronchi

Answer 28

two tube divisions leading to the left and right lung. lined with ciliated epithelium and mucus secreting goblet cells to remove dirt particles

Question 29

what are the bronchioles

Answer 29

smaller branches with smooth muscle walls, lined with ciliated epithelium

Question 30

what are alveoli

Answer 30

microscopic, elasticated, very thin air-sacs. closely associated with the pulmonary arteries. is the site of gas exchange

Question 31

name the six features of the alveolar epithelium as a surface over which gas exchange takes place

Answer 31

• ventilated from bronchioles (maintains conc gradient for gas exchange)
• thin, flat, one-cell thick alveolar walls (provides short diffusion distance so diffusion is rapid)
• alveolar epithelium walls folded to increase surface area
• moist to help gasses (CO2 + O2) dissolve
• associated with many capillaries (provide large SA:VOL ratio for gas exchange with blood)
• capillary cells thin

Question 32

describe inspiration in humans (5)

Answer 32

• external intercostal muscles contract
• diaphragm contracts
• volume in thorax increases
• air pressure decreases
• air pressure greater outside than inside so air flows in, inflating the lungs

Question 33

describe expiration in humans (6)

Answer 33

• internal intercostal muscles contract
• diaphragm relaxes
• elasticated alveoli recoil
• volume in thorax decreases
• air pressure increases
• air pressure in lungs greater than outside so air flows out, deflating the lungs