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Biology > Mass transport 7.1 - 7.9 > Flashcards

Mass transport 7.1 - 7.9 Flashcards

1
Q

Describe the quaternary structure of haemoglobin

A

4 polypeptides (2 alpha and 2 beta) link to form a spherical molecule

Each polypeptide has a haem group which contains a ferrous (Fe2+) ion

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2
Q

Is the oxygen concentration of haemoglobin at the lungs low or high?

A

high

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3
Q

Is the oxygen concentration of haemoglobin at respiring tissues low or high?

A

low

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4
Q

Is the CO2 concentration of haemoglobin at the lungs low or high?

A

low

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5
Q

Is the CO2 concentration of haemoglobin at respiring tissues low or high?

A

high

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6
Q

Is the affinity for oxygen high or low at the lungs?

What does this mean in terms of oxygen dissociation?

A

High

Oxygen readily associates but doesn’t easily dissociate

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7
Q

Is the affinity for oxygen high or low at the respiring tissues?
What does this mean in terms of oxygen dissociation?

A

Low

Oxygen readily dissociates but doesn’t easily associate

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8
Q

What is the difference in the affinity of haemoglobin for oxygen in mother and foetus?

A

Foetus has higher affinity than mother

At same ppO2 foetus haemoglobin can load more oxgen, which is necessary since oxygen moves from mother to foetus

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9
Q

How does DNA lead to different haemoglobin molecules having different affinities for oxygen?

A

-Different base sequence

-Amino acid/primary
structure is different

  • Therefore tertiary/quaternary structure is different
  • Shape is different
  • Different affinities
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10
Q

How does the dissociation of haemoglobin retain a reserve supply of oxygen?

A

Haemoglobin carries 4 oxygen molecules but only releases one when the body is at rest.
This means that there is a reserve supply for increased respiratory demands

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11
Q

Explain the initial low gradient in the oxygen dissociation curve

A

4 polypeptide chains are closely united so it is difficult for oxygen to find a binding site

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12
Q

Explain the rapid increase in gradient in the oxygen dissociation curve

A

First oxygen binding induces further binding due to changes in quaternary structure/shape

Smaller increase in partial pressure required to bind further oxygen molecules

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13
Q

Explain the leveling off of the oxygen dissociation curve

A

Majority of binding sites are occupied

-harder to find available site to bind to

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14
Q

As affinity of haemoglobin increases, what direction does the dissociation curve move?

A

left

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15
Q

Describe the bohr effect

A
  • When tissues respire CO2 levels increase
  • Rate of oxygen unloading increases
  • Affinity decreases/curve moves right
  • At same ppO2 blood saturation of oxygen is lower
  • More oxygen is released
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16
Q

Explain why the affinity of haemoglobin changes at respiring tissues

A
  • CO2 transported in blood
  • Blood pH decreases at tissues as CO2 increases (more acidic)
  • Decrease in pH changes shape of haemoglobin molecule
  • Oxygen dissociates more readily/affinity decreases
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17
Q

Explain why the affinity of haemoglobin changes at exchange surfaces

A
  • At lungs CO2 is constantly being removed so concentration is low
  • Blood pH increases as CO2 concentration decreases
  • Shape of haemoglobin changesso that affinity for oxygen increases
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18
Q

Explain the affinity of haemoglobin in a lugworm

A
  • Little oxygen available in environment when tide is out

- High affinity at low ppO2 to associate the maximum amount of oxygen available

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19
Q

Explain the affinity of haemoglobin in a llama

A

Low ppO2 due to high altitude and low atmospheric pressure.

-little O2 available in environment leads to high affinity to maximise association with O2

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20
Q

Why does birds’ haemoglobin have a lower affinity for oxygen than humans’?

A

Higher metabolic rate/respiratory demands means that O2 must be able to dissociate quicker

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21
Q

Why do large organisms need a mass transport system?

A
  • Lower SA:vol so demands cannot be met by diffusion alone

- Higher metabolic rate/respiratory demands

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22
Q

Why do mammals have a double circulatory system?

A
  • Blood pressure decreases by too much between lungs and body
  • High pressure is required to adequately supply all tissues and meet respiratory demands
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23
Q

What is the function of the septum in the heart and why is this important?

A

prevents mixing of blood in 2 sides of the heart

  • only partially O2 saturated blood would reach tissues so respiratory demands wouldn’t be met
  • concentration gradient decreased so less O2 uptake in lungs
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24
Q

What is the path taken by blood from the lungs, to the body, and then back to the lungs?

A

Lungs

pulmonary vein

left atrium

bicuspid/LAV valves

left ventricle

SL valves

aorta

body

vena cava

right atrium

tricuspid/RAV valves

right ventricle

SL valves

pulmonary artery

lungs

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25
Q

Which blood vessel is connected to the right atrium?

Does this carry oxygenated or deoxygenated blood?

A

Vena cava

deoxygenated

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26
Q

Which blood vessel is connected to the left atrium?

Does this carry oxygenated or deoxygenated blood?

A

Pulmonary vein

oxygenated

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27
Q

Which blood vessel is connected to the right ventricle?

Does this carry oxygenated or deoxygenated blood?

A

Pulmonary artery

deoxygenated

28
Q

Which blood vessel is connected to the left ventricle?

Does this carry oxygenated or deoxygenated blood?

A

Aorta

Oxygenated

29
Q

How can diet lead to coronary heart disease?

A
  • Too much saturated fat/cholesterol
  • Increased LDL/cholesterol in blood
  • Atheroma/fatty deposits form, blocking coronary arteries
  • Less O2 to heart muscle
  • Increase in blood pressure
  • Increased risk of aneurysm/embolism
30
Q

During atrial systole:

1) do atria contract/relax?
2) do ventricles contract/relax?
3) are AV valves open/closed?
4) are SL valves open/closed

A

1) contract
2) relax
3) open
4) closed

31
Q

During ventricular systole:
1) do atria contract/relax?

2) do ventricles contract/relax?
3) are AV valves open/closed?
4) are SL valves open/closed

A

1) relax
2) contract
3) closed
4) open

32
Q

During diastole:

1) do atria contract/relax?
2) do ventricles contract/relax?
3) are AV valves open/closed?
4) are SL valves open/closed

A

1) relax
2) relax
3) open
4) closed

33
Q

When AV valves are open:

1) Is atrial pressure high/low?
2) Is ventricular pressure high/low?

A

1) high

2) low

34
Q

When AV valves are closed:

1) Is atrial pressure high/low?
2) Is ventricular pressure high/low?

A

1) low

2) high

35
Q

When SL valves are open:

1) Is atrial pressure high/low?
2) Is ventricular pressure high/low?

A

1) high

2) low

36
Q

When SL valves are closed:

1) Is atrial pressure high/low?
2) Is ventricular pressure high/low?

A

1) low

2) high

37
Q

When blood pressure is higher on the convex side, does the valve open or close?

A

Opens

38
Q

When blood pressure is higher on the concave side, does the valve open or close?

A

Closes

39
Q

Name the valves found in veins

A

Pocket valves

40
Q

How do you calculate cardiac output?

A

SV x HR

41
Q

Name the sequence of blood vessels in order of decreasing blood pressure

A 
Arteries
arterioles 
capillaries 
venules 
veins
42
Q

Is the lumen of an artery narrow/wide?

Why?

A

Narrow

to maintain high pressure

43
Q

Is the lumen of a vein narrow/wide?

A

Wide

44
Q

Is the muscle layer of an artery thick or thin?

Why?

A

Thick

can contract to control blood flow to tissues

45
Q

Is the muscle layer of a vein thick or thin?

Why?

A

Thin

veins carry blood away from tissues and therefore their constriction and dilation cannot control blood flow to tissues

46
Q

Is the elastic layer in arteries thick or thin?

Why?

A

Thick
elastic stretches in systole and recoils in diastole to maintain high pressure (required for blood to reach all extremeties of the body) and smooth pressure surges created by the beating of the heart

47
Q

Is the elastic layer in veins thick or thin?

Why?

A

Thin

low pressure in veins will not cause them to burst and pressure is too low to create recoil action

48
Q

Do arteries have valves?

Why?

A

No (except leaving the heart)
blood is under constant high pressure due to heart continuously pumping blood into arteries so blood doesn’t flow backwards

49
Q

Do veins have valves?

Why?

A

Yes (pocket valves)
Pressure is low so blood may flow backwards

when body muscles contract, veins are compressed, pressurising blood within them. Valves ensure that this pressure directs blood in one direction only

50
Q

Do arteries carry oxygenated or deoxygenated blood?

A

Oxygenated (except for pulmonary artery)

51
Q

Do veins carry oxygenated or deoxygenated blood?

A

Deoxygenated (except pulmonary vein)

52
Q

How is tissue fluid formed?

A
  • high hydrostatic pressure forces water out of capillaries
  • large proteins remain
  • wp decreases
53
Q

How is tissue fluid returned?

A
  • Lowered wp in capillary due to plasma proteins
  • Water enters capillary by osmosis
  • Remaining tissue fluid enters lymphatic system
54
Q

Why does hydrostatic pressure decrease along capillary?

A

loss of fluid/volume

frictions/resistance of capillary wall

55
Q

Why does lack of protein in the blood lead to the build up of tissue fluid?

A

-wp in capillary is not as low so wp gradient decreases
-less/no water absorbed into the capillary by osmosis
so more tissue fluid forms at arteriole end.

56
Q

Describe how a water potential gradient is established by movement of water across a leaf

A

🔹heat from sun means that water evaporates from mesophyll to air spaces

🔹these mesophyll cells now have lower water potential so water enters from neighbouring cells

🔹water potential of these neighbouring cells therefore decreases

🔹they in turn take water from their neighbours via osmosis

57
Q

Describe the movement of water up the xylem

A

🔹evaporation of water from mesophyll

🔹water molecules stick together due to hydrogen bonding (cohesion)

🔹water forms continuous unbroken column across mesophyll and down xylem

🔹as more water evaporates from leaf, more molecules are drawn up behind as a result of cohesion creating negative pressure in xylem (transpiration pull)

58
Q

What is the mass flow hypothesis for the mechanism of translocation on plants?

A

🔹Sucrose is produced at the source

🔹Transported from source to phloem/STE via active transport through companion cells

🔹Water potential of STE decreases as sucrose enters, so water enters STE from xylem by osmosis

🔹The increased volume of water increases hydrostatic pressure and induces the mass movement of sucrose down the STE to the sink

59
Q

What is sucrose used for in the roots?

A

🔹Respiration

🔹Converted into starch and stored

60
Q

What is the evidence supporting the mass flow hypothesis?

A

🔹pressure on sieve tubes (shown by sap being released when they’re cut)

🔹concentration of sucrose higher in source than sink

🔹downward flow in phloem only occurs in daylight

🔹increases in sucrose levels in leaves followed by sucrose increase in phloem

🔹metabolic positions and lack of O2 inhibit translocation of sucrose in phloem

🔹companion cells have many mitochondria

61
Q

What is the evidence against the mass flow hypothesis?

A

🔹Function of sieve plates is unclear as they would seem to hinder mass flow

🔹Not all solutes move at same speed -they should do if mass flow is correct

🔹Sucrose delivered at same rate to all regions -rather than quicker to areas of lower concentration

62
Q

In photometer experiments why is the shoot cut underwater?

A

To prevent air bubbles entering xylem

63
Q

Describe how you would use a simple respirometer to measure the oxygen uptake of 5g of maggots

A
  • marker fluid in capillary tube
  • KOH or soda lime to absorb carbon dioxide
  • weigh organisms
  • mark starting point of fluid
  • close taps
  • maggots will take in oxygen from capillary tube, causing marker to move down
  • time until marker reaches set distance
  • record distance travelled by fluid and time taken
  • repeat
64
Q

How do you ensure the reliability of a respirometer experiment?

A
  • Set up control experiment using beads

* Keep apparatus in water bath to prevent temperature fluctuations causing pressure change

65
Q

How does a control respirometer experiment increase the accuracy of the results?

A

Any change in position of marker will be due to temperature fluctuations causing pressure change

This change is calculated and subtracted from the results to find the change in pressure caused by respiration

66
Q

How does an asthma attack decrease the mean FEV?

A
  • Muscle walls of bronchi/bronchioles contract
  • Walls of bronchi/bronchioles secrete more mucus
  • Diameter of airways reduced
  • Flow of air reduced
67
Q

Explain the mechanism that causes forced expiration

A
  • Contraction of INTERNAL intercostal muscles
  • Relaxation of EXTERNAL intercostal muscles
  • Relaxation of diaphragm
  • Decrease in vol of thorax
  • Air pushed down pressure gradient

Biology (6 decks)

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