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A-level Biology > 3.1 Adaptations for Gas Exchange > Flashcards

3.1 Adaptations for Gas Exchange Flashcards

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1
Q

gas exchange

A

process by which oxygen reaches the cells and carbon dioxide is removed from them

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2
Q

ventilation

A

the process of moving the respiratory medium (air or water) over the respiratory surface to maintain a concentration gradient

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3
Q

respiration

A

series of chemical reactions that results in the release of energy in the form of ATP

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4
Q

respiratory pigment

A

a molecules which increases the oxygen carrying capacity of the blood
e.g haemoglobin

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5
Q

tracheae

A

a system of branched chitin lined air tubes in insects

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6
Q

ends of tracheoles

A

site of gas exchange in insects

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7
Q

spiracles

A

holes in an insects exoskeleton which can open and close like valves to allow exchange of gases and reduce water loss which can lead to dehydration

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8
Q

gill lamellae

A

site of gas exchange in fish

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9
Q

alveoli

A

site of gas exchange in mammals

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10
Q

why is diffusion slower in larger organisms

A

the larger the organism the longer the diffusion pathway so the longer it takes for gases to reach the centre of the cell

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11
Q

unicellular organism that lives in water

A

amoeba

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12
Q

gas exchange in amoebas

A 
extremely large SA:V
occurs across whole cell membrane
permeable membrane
no specialised system required
diffusion sufficient to meet oxygen requirements
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13
Q

multicellular organism that lives in water

A

flatworm

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14
Q

gas exchange in flatworms

A

increased SA:V due to flattened shape
short diffusion pathway
no specialised system
diffusion across membrane sufficient enough to meet oxygen requirements

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15
Q

multicellular organism that lives on land

A

earthworm

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16
Q

gas exchange in earthworms

A

tubular shape
live in damp environments
secret mucus to keep cells moist for gases to dissolve
elongated shape for large SA:V
blood vessels close to surface for easy diffusion
blood circulation maintains a concentration gradient
contain haemoglobin to carry oxygen to cells

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17
Q

why do larger organisms require specialised gas exchange organs (6 reasons)

A
  1. small SA:V
  2. diffusion insufficient
  3. more metabolically active
  4. long diffusion path
  5. method of circulation to distribute gases
  6. animals with toughened body surface need internal exchange surfaces
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18
Q

all respiratory surfaces must be…

A
  1. moist so gases can dissolve
  2. thin so there is short diffusion path
  3. permeable so gases can diffuse easily
  4. large SA:V so more room for diffusiont
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19
Q

gas exchange in insects

A

do not use blood to transport gases.
air diffuses into the insect through holes in the exoskeleton called spiracles.
the spiracles leas to branched air tubes lined with chitin called trachea.
the trachea branch into tracheoles.

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20
Q

how are the ends of trachioles adapted for gas exchange

A

they are filled with fluid to keep the gas exchange interface moist so gases can easily dissolve

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21
Q

what are the advantages of a tracheal system

A
  1. oxygen supplied directly to tissues
  2. no respiratory pigment needed
  3. oxygen diffuses faster in air than blood
  4. spiracles can close to reduce water loss and prevent dehydration
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22
Q

why are some gas exchange systems retained inside the body

A

to reduce water loss
to reduce heat loss
protected by the ribcage or the exoskeleton in insects

23
Q

parallel flow

A

gas exchange system where blood in the gill capillaries circulates in the same direction as water flowing over the gills

24
Q

counter current flow

A

gas exchange system where blood in the gill capillaries circulates in the opposite direction to water flowing over the gills

25
Q

which fish use parallel flow

A

Cartilaginous fish

shark

26
Q

which fish use counter current flow

A

bony fish

herring

27
Q

operculum

A

bony structure in bony fish that provides a protective covering for the gill

28
Q

what are the 3 problems caused by living in water

A
  1. rate of diffusion is slower in water
  2. water is more dense so can’t move as freely
  3. less oxygen dissolved in water than air
29
Q

ventilation mechanism in fish as water flows in

A 
mouth opens
operculum closes
buccal cavity floor lowers
volume increases
pressure decreases
water flows in
30
Q

ventilation mechanism in fish as water flows out

A 
mouth closes
operculum opens
buccal cavity floor rises
volume decreases
pressure increases
water flows out
31
Q

what is the maximum oxygen saturation in parallel flow

A

50%

32
Q

what are tadpoles gas exchange surface

A

gills

33
Q

what is frogs gas exchange surfaces

A

moist skin

simple lungs

34
Q

describe the structure of frogs lungs

A

a simple structure with little inholdings of the gas exchange tissue

35
Q

why is there rings of cartilage around the trachea and bronchus

A

to stop the airways from collapsing during inspiration when the pressure is low

36
Q

the airtight compartment of the body that encloses the lungs

A

the thorax

37
Q

ventilation mechanism in inspiration of humans

A

ribs move up and out
external muscles contract
outer pleural membrane pulled outwards reducing the pressure in the pleural cavity
inner pleural membrane pulled outwards
lungs surface is drawn out
alveoli expand
pressure in the alveoli is lower than atmospheric pressure so air moves in

38
Q

ventilation mechanism in expiration of humans

A

ribs move down and in
external muscles relax
outer pleural membrane pulled inwards increasing pressure in the pleural cavity
lungs surface is drawn in
alveoli deflate
pressure in the alveoli higher than atmospheric pressure so air moves out

39
Q

how are alveoli suitable for gas exchange

A

large SA:V for the diffusion of gases
moist so gases can dissolve
permeable so gases can diffuse
one cell thick for a short diffusion pathway
extensive cappilary network maintains a concentration gradient

40
Q

epiglottis

A

the flap of skin that stops food entering the trachea when swallowing

41
Q

larynx

A

box shaped structure above the trachea containing the vocal cords

42
Q

bronchus

A

trachea splits into two of these

43
Q

pleural fluid

A

acts as a lubricant allowing friction free movement against the inner wall of the thorax

44
Q

what are 7 adaptations of leaves for photosynthesis

A
  1. large surface area to absorb as much light as possible
  2. leaves can orientate towards the sun
  3. leaves are thin to allow light to penetrate through layers
  4. the cuticle and epidermis are transparent to allow light to pass to the mesophyll
  5. palisade cells are elongated and densely packed and contain many chloroplasts
  6. intracellular air spaces allow diffusion of gases
  7. chloroplasts can rotate within the mesophyll cellist maximise light absoprtion
45
Q

what 4 adaptations do leaves have for gas exchange

A
  1. leave blade is thin, short diffusion pathway
  2. spongy mesophyll, allows diffusion and circulation of gases to maintain a concentration gradient
  3. moist mesophyll walls, allow gases to dissolve
  4. stomatal pores, allow diffusion of gases
46
Q

where are the stomata found

A

in the lower epidermis

47
Q

how many guard cells surround the stoma

A

2

48
Q

how are guard cells specially adapted

A

they contain chloroplasts
they have unevenly thickened cell walls
many mitochondria

49
Q

when the guard cells are turgid the stomatal pore…

A

opens

50
Q

when the guard cells are flaccid the stomatal pore…

A

closes

51
Q

explain the 4 steps of the mechanism for the stomatal opening

A
  1. k+ ions are actively transported from epidermal cells into the guard cells
  2. stored starch (insoluble) is converted to malate (soluble) by enzymes in the cytoplasm
  3. therefore, water potential inside the guard cells is lowered so water enters by osmosis
  4. the guard cells become turgid and curve apart as the inner cell walls are thicker than the outer cell walls
52
Q

why are stomata open during the day

A

to allow diffusion of gases for respiration and photosynthesis

53
Q

why are stomata closed at night

A

to reduce the loss of water vapour

A-level Biology (9 decks)

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