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AS BIO UNIT2 > 2.2 Adaptations for Gas Exchange > Flashcards

2.2 Adaptations for Gas Exchange Flashcards

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1
Q

Diffusion of a substance is

A

Directly proportional to their surface area

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2
Q

What does volume of nutrients depend on?

A

Volume (bulk), activity levels and metabolic rate

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3
Q

What makes a good gas exchange surface?

A
  • large SA (often highly folded) as more space for molecules involved
  • thin barrier (one cell thick) to reduce diffusion distance
  • fresh supply and removal of molecules to maintain steep diffusion gradient
  • moist
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4
Q

Explain flatworms in terms of gas exchange

A
  • flat so larger surface area than spherical organism of the same volume
  • very short diffusion path
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5
Q

Explain earthworms in terms of gas exchange

A
  • cylindrical so small SA:V ratio
  • skin is a respiratory surface so kept moist by mucus secretion
  • low O2 requirement as slow moving and low metabolic rate
  • haemoglobin helps to maintain diffusion gradient at surface
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6
Q

Explain multicellular organisms in terms of gas exchange

A
  • higher metabolic rate so need to deliver more O2 to cells
  • increased size and specialisation of cells so tissues and organs more interdependent
  • steep conc gradient
  • respiratory surfaces v thin & protected as inside organism
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7
Q

Define ventilation

A

Bringing gases to or from a gas exchange surface

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8
Q

Define metabolic rate

A

The rate of energy expenditure of the body
—> respiration, O2, activity

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9
Q

Why is metabolic rate greater in mammals and birds than fish?

A

Feathers and fur lead to higher constant body temp

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10
Q

2 ways a diffusion gradient is maintained in multicellular organisms

A
  • blood flow
  • respiratory pigments ie haemoglobin
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11
Q

Inspiration in fish

A
  • mouth open, operculum closed, floor of mouth down, volume in mouth increase, pressure in mouth decrease, water movement in as external pressure higher
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12
Q

Expiration in fish

A
  • mouth closed, operculum open, floor of mouth up, volume decrease and pressure increase, water movement out as internal pressure higher
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13
Q

What are pleural membranes?

A

Thin, fluid filled membrane that surrounds the outer surface of the lungs and lines the inner wall of the chest cavity

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14
Q

Inhalation in mammals

A
  • diaphragm flatten and intercostal muscles contract, rib position fill up and move out, thorax volume increase and pressure in thorax decrease, air moves in
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15
Q

Exhalation in mammals

A
  • diaphragm relax and dome, intercostal muscles relax, ribs empty and move in, thorax volume decrease and pressure increase, air move out
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16
Q

What vessels take blood to and from heart?

A

Pulmonary artery = blood to lungs
Pulmonary veins = blood to heart and away from lungs

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17
Q

Explain gas exchange in cartilaginous fish

A
  • parallel flow of blood and water
    —> oxygen diffuse from concentrated to less concentrated areas but can only continue until the water and blood O2 concentrations are equal as concentration gradient is not maintained past this point
  • does not occur continuously across whole gill lamella
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18
Q

Explain gill structure in bony fish

A
  • each gill supported by a gill arch
  • thin projections called gill filaments on each arch
  • gill lamellae for gas exchange
    —> stick together when not in water hence fish die on ground
19
Q

Explain gas exchange in bony fish

A
  • water move from mouth cavity to opercular cavity and into gill pouches where it flows between gill lamellae
  • counter current flow enables conc gradient to be maintained and therefore diffusion along entire length of lamellae
  • gills extract 80% of available oxygen
20
Q

Why is parallel flow less efficient than counter current?

A
  • O2 only diffused to equilibria
  • does not occur across whole gill lamellae
    —> therefore less O2 uptake
21
Q

Suggest why gill lamellae would not be efficient on land

A
  • dry out so oxygen cannot dissolve so fish suffocate
  • stick together which decreases SA therefore less gas exchange
22
Q

Explain efficient adaptations for gas exchange in mammalian respiratory system

A
  • many alveoli which are highly folded to increase SA therefore gas exchange efficiency
  • one cell thick - short diffusion path
  • capillaries to maintain rich blood supply which maintains concentration gradient for diffusion
23
Q

Why do mammals need a complex ventilation system?

A
  • high metabolic rate
  • ventilation maintains steep concentration gradient so more O2 can be diffused
24
Q

Give 2 advantages of humans having internal gas exchange surfaces

A

Reduce heat and water loss

25
Q

Stage one medical use of artificial surfactant and explain why it would be needed

A
  • premature babies
  • lowers surface tension of fluid in the alveoli to prevent alveoli from collapsing
26
Q

Function of gill rakers

A

Filter large molecules and sediment

27
Q

What part of the respiratory system becomes inflamed during an asthma attack?

A

Bronchioles

28
Q

What part of the respiratory system contains a surfactant to reduce surface tension?

A

Alveoli

29
Q

In the trachea, what is the function of the ciliated epithelial layer?

A

Beat and move mucus/bacteria upward

30
Q

In trachea, what is the function of the layer of cartilage?

A

Prevent trachea closing during inspiration

31
Q

In the trachea, why is the cartilage not in a complete ring?

A

To enable oesophagus to expand when eating

32
Q

How do insects reduce water loss?

A

A waterproof layer covering body surface
- exoskeleton has thin waxy layer over chitin

33
Q

Explain gas exchange in insects

A
  • occurs through paired holes called spiracles running along the side of the body
  • spiracles lead into a system of branched, chitin lined air tubes called tracheae, which branch to smaller tubes called tracheoles
  • spiracles able to open and close for gas exchange and to reduce water loss
  • hair on spiracles present water loss and prevent solid particles getting in
34
Q

One advantage and one disadvantage of the tracheal system

A

A: oxygen delivered directly to cells
D: size/shape limitation

35
Q

Why does amoeba not need a specific aliased gas exchange system?

A
  • diffusion of gas dp to surface area
  • very large SA:V ratio
  • gets sufficient oxygen through simple diffusion
36
Q

How do mammals maintain conc gradient?

A

Blood flow and ventilation

37
Q

Explain the difference in size of bird and mammalian red blood cells

A
  • mammalian evolved when O2 levels lower
  • biconcave shape increase SA for O2 diffusion
  • no nucleus so carry more haemoglobin
  • small so short diffusion distance
  • high SA:V ratio
38
Q

Explain the causes of the pressure and volume changes shown during inspiration

A
  • expanding rib cage lowers pressure in pleural cavity
  • inner pleural membrane pulls on lungs which increases lung volume which decreases pressure in lungs
  • below atmospheric pressure so air moves in
39
Q

Explain how the outward movement of the rib cage causes changes in the pleural and alveolar pressures during inspiration

A
  • intercostal muscles contract and expand the rib cage which pulls out pleural membranes
  • pleural pressure reduced and inner pleural membranes expand alveoli which decreases alveoli pressure and so air moves in
40
Q

What are stomata?

A

Pores on lower leaf surface, and other areal parts of a plant, bounded by two guard cells through which gases and water vapour diffuse

41
Q

How do the stoma open?

A
  • chloroplasts in the guard cells photosynthesise, producing ATP
  • ATP provides energy for active transport of potassium ions into guard cells from surrounding epidermal cells
  • stored starch converted to a late ions
  • the K+ and a late ions lower the water potential in the guard cells making it more negative so water enters cells by osmosis
  • the cells of guard cells are thinner in some places than others so expand as thy absorb water, but expand less in areas where cell wall thick
  • pore appears between the thicker areas, which is the stoma
42
Q

Why do the guard cells form a banana like shape?

A

Radial cellulose fibres

43
Q

When and why do stomata close?

A
  • at night to prevent water loss when there is insufficient light for photosynthesis
  • in very bright light as this is generally accompanied by intense heat which old increase evaporation
  • if there is excessive water loss

AS BIO UNIT2 (7 decks)

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