12.10 Gas Exchange Flashcards

1
Q

for survival an organism must to what effectively with its environment

A

exchange materials

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2
Q

examples of materials that need to be exchanged -> respiratory gases

A

O2 and CO2

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3
Q

examples of materials that need to be exchanged -> nutrients

A

glucose, amino acids and lipids

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4
Q

examples of materials that need to be exchanged -> excretory products

A

CO2 and Urea

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5
Q

examples of materials that need to be exchanged -> other

A

heat

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6
Q

exchange takes place at the what of the organism

A

surface

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7
Q

the materials absorbed are what by the cell

A

used (assimilated)

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8
Q

the cell / cells of the organism make up its…

A

volume

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9
Q

for exchange to be effective…

A

the SA of the organism must be large compared to its volume

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10
Q

the SA to V ratio gets smaller as what

A

the object gets larger

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11
Q

SA to V ratio decreases as an organism gets…

A

larger

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12
Q

O2 is required to produce what during what

A

ATP
aerobic respiration

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13
Q

when is CO2 produced and as what

A

produced as a waste product during this process (aerobic respiration)

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14
Q

what does this produce (when CO2 is produced in aerobic respiration as a waste product)

A

produces concentration gradients of these gases in opposite directions

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15
Q

all organisms rely on what for the exchange of O2 and CO2 down their concentration gradients

A

diffusion

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16
Q

single celled organisms (protists and prokaryotes) and some small multicellular organisms have what to meet their gas exchange needs by what across their cell membranes

A

have large enough SA to V ratio
by diffusion

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17
Q

larger organisms (humans, other mammals, insects and fish) have what (by comparison) so cannot rely on what (alone) to meet the oxygen demands to what

A

have relatively small SA to V ratios
can’t rely on diffusion (alone)
demands to all of their cells

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18
Q

therefore larger organisms have developed what and systems which have what to ensure the what

A

developed specialised gas exchange surfaces
have adaptations
ensure the rapid diffusion of gases

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19
Q

larger organisms have…

A

a smaller SA to V ratio

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20
Q

smaller organisms have…

A

a larger SA to V ratio

21
Q

fick’s law (equation)

A

rate of diffusion = (SA x conc gradient) / diffusion distance or pathway

22
Q

what makes a good exchange surface

A
  • large SA
  • large conc gradients
  • thin exchange surface (few membrane or thin walls)
23
Q

dilema of terresterial (land living) insects

A

the need for gas exchange vs the need to conserve water

24
Q

gas exchange insects: the most effective surface for gas exchange is a…

A

a large, thin and permeable area

25
gas exchange in insects: these features are also favourable for what leading to potentially what
favourable for evaporation potentially fatal dehydration (dessication)
26
insects must therefore do what to water loss and gas exchange
balance them
27
to limit water loss insects may have (2)...
1 waterproof covering over their body surfaces. this is usually a rigid outer skeleton (exoskeleton) covered with a waterproof cuticle 2 relatively small SA to V ratio to minimise the area over which water is lost
28
movement of O2 through the insect
1 oxygen enters the insect through spiracles and into the tracheae 2 spiracles close 3 oxygen diffuses through the tracheae into the tracheoles (down a conc gradient) 4 oxygen is delivered directly to the respiring tissues
29
what happens to CO2 during the process (movement of oxygen through the insect)
CO2 produced by (aerobically) respiring tissues moves in the opposite direction and exits the insect when spiracles open
30
what are tracheoles and how are they adapted for efficient gas exchange
- small tubes with thin walls so that the diffusion distance is reduced which extend throughout the body tissues - highly branched so that there is a large SA
31
what are tracheae and how are they adapted for efficient gas exchange
- network of tubes supported by strengthened rings - provides tubes full of air so that diffusion is fast
32
why diffusion happens in the gas exchange systems (tracheal system) of insects -> O2 diffusion
1 tissues respire using oxygen, which reduces the conc of oxygen at the tissue 2 oxygen moves from an area of higher conc to lower conc so moves from the tracheae to the tissue 3 this lowers the oxygen conc in the tracheae so oxygen moves into the tracheae from outside the insect via the spiracles
33
why diffusion happens in the gas exchange systems (tracheal system) of insects -> CO2 diffusion
1 respiration produces CO2 increasing the conc at the tissue 2 CO2 moves from an area of high conc at the tissue to the low conc in the tracheae 3 CO2 then moves from high conc in tracheae to low conc outside the insect via the spiracles
34
ventilation (abdominal pumping) in insects
movement of the insects muscles creates a mass movement of air in and out of the tracheae (like a bellow action) thus increasing the rate of gaseous exchange they also have small air sacs in their trachea muscles around the trachea contract and pumps the air in the sacs deeper into the tracheoles
35
how do insects get additional oxygen during flight
- when an insect is at rest, water can build up in the tracheoles - during flight, the insect may partly respire anaerobically and produce some lactate (lactic acid) - this lowers the water potential of the muscle cells. as lactate builds up, water passes via osmosis from the tracheoles into the muscle cells - this adaptation draws air into the tracheoles closer to the muscle cells and therefore reduces the diffusion distance for oxygen when its most needed - so faster diffusion through the air to the gas exchange surface - so larger SA for gas exchange
36
what is the gas exchange organ in fish
gills
37
the gills have what
a large SA
38
each fish has how many gills each side of its head
4
38
how does water move in and out of the fish
water moves in through the mouth and out through / over the gills
39
the gills have finger-like projections called...
gill filaments
39
what happens to the oxygen when water moves in and out of the fish
water carrying oxygen enters thriugh the fish's mouth, passes through the lamellae on the gill filaments where most of the oxygen is removed finally water containing little oxygen leaves through gill opening
40
each filament has many...
lamellae (at 90°C to increase SA)
41
points about lamellae
- each gill filament has gill lamellae - gill lamellae are positioned at right angles to the filaments - lamellae contain capillaries - thin epithelium (for short distance between water and blood)
42
explain 2 ways in which the structure of fish gills is adapted for efficient gas exchange (2)
1 many filaments / lamellae so theres a large surface area 2 lamellae are thin for a short diffusion pathway
43
countercurrent flow in fish gills
1 water and blood flow in opposite directions 2 blood always passing water with a higher oxygen concentration (in water) 3 oxygen diffusion / conc gradient maintained across the full length of the gill lamellae / filaments
44
ventilation in fish gills
ventilation so maintains a conc gradient
45
what are 2 cell layers in fish gills
1 thin epithelium of the lamellae 2 endothelium well of the capillary
46
a fish uses its gills to absorb oxygen from water. explain how the gills of a fish are adapted for efficient gas exchange (6)
1 large SA provided by many lamellae / filaments so that increases diffusion / makes diffusion efficient 2 thin epithelium of lamellae / distance between water and blood so there is a short diffusion distance 3 water and blood flow in opposite directions / counter current so that a conc gradient (along gill) is maintained / equilibrium not reached 4 as water always next to blood with lower conc of oxygen 5 circulation replaces blood saturated with oxygen 6 ventilation replaces water (as oxygen removed)