Gas Exchange Flashcards

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1
Q

what do single celled organisms do?

A
  • absorb and release gases by diffusion through their cell-surface membrane
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2
Q

what adaptations do single-celled organisms have?

A
  • relatively large surface area
  • thin surface
  • short diffusion pathway
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3
Q

why do fish need to have a specialised gas exchange surface?

A
  • lower concentration of oxygen in water than in air
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4
Q

what is the function of the gills?

A

water containing oxygen enters the fish through its mouth and passes out the mouth through the gills

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5
Q

what is each gill made of?

A
  • lots of thin plates called gill filaments
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6
Q

why is it a good thing to have gill filaments?

A
  • there are many of them which gives a large surface area for exchange of gases = increases the rate of diffusion
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7
Q

what are the gill filaments covered in?

A
  • tiny structures called lamellae
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8
Q

why is it good to have lamellae?

A

increases the surface area

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9
Q

how are lamellae adapted for diffusion?

A
  • lots of blood capillaries = ventilation
  • thin surface layer of cells = thin diffusion pathway
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10
Q

what is the counter-current system?

A
  • in the gills of fish water and blood flow in opposite directions through the lamellae
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11
Q

what does the counter-current system enable?

A
  • a concentration gradient of oxygen to be maintained across the whole length of the lamella
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12
Q

why is it good to have a counter current system?

A
  • ensures that as much oxygen can diffuse from the water into the blood
  • oxygen can diffuse across the whole length of the lamellae
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13
Q

what concentration does blood enter the lamella in?

A

low concentration of oxygen

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14
Q

what are the adaptations of fish in gas exchange?

A
  • gills
  • gill lamellae
  • gill filaments
  • counter current principle
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15
Q

what is the main gas exchange surface in the leaf?

A

mesophyll cells

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16
Q

how are mesophyll cells adapted for gas exchange?

A

they have a large surface area

17
Q

where is the mesophyll cell?

A

inside the leaf

18
Q

how do gases move in and out the epidermis?

A

pores called stomata

19
Q

what do stomatas do?

A
  • open to allow the exchange of gases
  • close to reduce water loss
20
Q

what controls the opening and closing of stomata?

A

guard cells

21
Q

how are the leaves of dicotyledonous plants adapted for gas exchange?

A
  • mesophyll
  • stomata
22
Q

what do the tracheae branch off into?

A

tracheoles

23
Q

how does air move into the tracheae of an insect?

A
  • pores on the surface of tracheae called spiracles
24
Q

what does the gas exchange surface of an insect look like?

A
  • spiracles
  • tracheae
  • tracheoles
25
Q

what does the tracheae branch off into?

A
  • smaller tracheoles which have thin, permeable walls
26
Q

what system do insects have?

A

tracheal system (tracheae, tracheoles and spiracles)

27
Q

how can insects control the loss of water?

A
  • open and closing their spiracles using muscles
  • waterproof, waxy cuticle
  • tiny hairs around spiracles
    = reduce evaporation
28
Q

what are xerophytes?

A

plants which are adapted for life in warm, dray or windy habitats

29
Q

how are xerophytic plants adapted to reduce water loss(5)?

A
  • stomata sunk in pits
  • layer of hairs on the epidermis
  • curled leaves
  • reduced number of stomata
  • thicker waxy, waterproof cuticles
30
Q

how is stomata sunk in pits advantageous for xerophytic plants?

A
  • trap water vapour
  • reducing concentration gradient of water between leaf and air
  • reduces evaporation of water from the leaf
31
Q

how is layer of hairs advantageous for xerophytic plants?

A
  • trap water vapour around the stomata
32
Q

how are curled leaves with the stomata inside advantageous for xerophytic plants?

A
  • protects them from the wind as wind increases rate of diffusion and evaporation
33
Q

how is a reduced number of stomata advantageous for xerophytic plants?

A
  • fewer areas for the water to escape from
34
Q

how is a thicker waxy, waterproof cuticles advantageous for xerophytic plants?

A
  • on leaves and stem to reduce evaporation
35
Q

what is an adaptation of the tracheae?

A
  • provide tubes full of air so fast diffusion