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Biology AQA A Level > Mass Transport Ch.7 > Flashcards

Mass Transport Ch.7 Flashcards

1
Q

The structure of Haemoglobin

A

A protein molecule with a Quaternary structure. Has 4 polypeptides. Each polypeptide is attached to Fe2+ ion. Each Fe2+ ion can bind with one O2. A total of 4 O2 can bind to haemoglobin.

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2
Q

What is the equation for haemoglobin loading

A

haemoglobin + oxygen = oxhaemoglobin

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3
Q

What is the equation for heamoglobin dissociating

A

oxhaemoglobin = haemoglobin + oxygen

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4
Q

What is high affinity for O2

A

O2 is readily taken up but releases it less easily

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5
Q

What is low affinity for O2

A

O2 is released readily but taken up less easily

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6
Q

What is the role of haemoglobin

A

To transport oxygen

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7
Q

Where does O2 readily dissociate?

A

Places where oxygen is required and concentration of oxygen is low (tissues ) E.g. muscles

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8
Q

Where does O2 readily associate with oxygen?

A

At the surface of gas exchange, where oxygen concentration is high. E.g lungs

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9
Q

What is partial pressure of oxygen?

A

The concentration of oxygen. the hypothetical pressure of oxygen if it alone occupied the entire volume

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10
Q

How does the concentration of CO2 relate to the pH?

A

The higher the CO2 concentration the lower the pH.

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11
Q

How does the pH relate to the structure of haemoglobin?

A

When the pH lowers the shape/structure of haemoglobin changes and the affinity for oxygen lowers. pH high= higher affinity

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12
Q

High CO2 concentration has low or high affinity?

A

Low affinity

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13
Q

Low CO2 concentration has low or high affinity?

A

High affinity

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14
Q

Explain the shape of the oxygen dissociation curve?

A

First O2 is hard to bind because of the shape of haemoglobin. After first binds the Quaternary structure changes and 2nd and 3rd O2 binds easier. The 4th O2 is hard to bind too because there is less chance for the O2 to bind to a free iron.

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15
Q

What does it mean if the oxygen dissociation curve is more to the right?

A

Lower affinity in general, realises oxygen more readily

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16
Q

What does it mean if the oxygen dissociation curve is more to the left ?

A

Higher affinity in general, binds with oxygen more readily.

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17
Q

Define Mass Transport

A

Large scale transport of substances through a transport system to and from exchange surfaces.

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18
Q

What determines whether an organism needs a specialised transport system or a pump.

A

Surface area: volume ratio (lower=bigger organism=needs specialised system+pump). More active= needs specialised system+ pump.

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19
Q

Hepatic is?

A

Liver

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20
Q

Renal is?

A

Kidney

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21
Q

Explain the route the blood takes on the right side of the heart?

A

(superior/inferior) vena cava

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22
Q

How do valve work?

A

By difference in blood pressure

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23
Q

What is the use of valves?

A

To prevent backflow

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24
Q

Where are the Atrioventricular valves?

A

Valves between the arteries and ventricle

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25
Q

Where are the Semi-lunar valves?

A

After the ventricle, in the aorta and pulmonary artery

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26
Q

Whats the name of the blood vessel that supplies blood to the heart?

A

coronary artery

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27
Q

What is systole?

A

contract

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28
Q

What is diastole?

A

Relaxing

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29
Q

Why is the Aortic pressure always relatively high?

A

Has to pump blood all around the body so needs a lot of force and high pressure. Elastic recoil the keeps this high pressure

30
Q

Why is the atrial pressure always relatively low?

A

Atrium’s have thin walls and only need to pass blood into the ventricle therefore not much pressure or force is required.

31
Q

What’s the structure of capillary?

A

Only an endothelium cell lining

32
Q

What’s the structure of an artery?

A

Narrow lumen, endothelium cell lining, thick elastic layer and muscular layer, no valves (except aorta) and thick outer layer.

33
Q

What’s the structure of a vein?

A

Large lumen, endothelium cell lining, thin elastic and muscular layer, valves and thin walls.

34
Q

What’s the advantage of the capillaries structure?

A

Short diffusion pathway for the exchange of substances

35
Q

What’s the advantage of the arteries structure?

A

Narrow lumen maintains high pressure, thick elastic and muscular layer means it can stretch and contract to help pump blood. Thick outer layer ensures the artery doesn’t burst with this high pressure.

36
Q

What’s the advantage of the veins structure?

A

Large lumen to accommodate the slow moving blood. Thin elastic and muscle wall because blood does not move in pumps. Thin outer layer/wall because low pressure so no chance of bursting.

37
Q

Where is tissue fluid found?

A

It surrounds cells and tissue

38
Q

What is tissue fluid used for?

A

Used as and exchange medium carries oxygen, glucose, water, amino acids and ions to cells and removes CO2 and urea.

39
Q

By what mechanism is tissue fluid made?

A

Hydrostatic pressure

40
Q

How is tissue fluid formed?

A

There is a higher hydrostatic pressure in the arteriole than in the surroundings due to the heart pumping. As a result ultra filtration occurs and small molecules such as glucose, water and oxygen are pushed out of the capillary. This is tissue fluid.

41
Q

Why is tissue fluid reabsorbed into the capillary.

A

At the veinous end of the capillary due to the loss of tissue fluid, the water potential is more negative than before. The loss of tissue fluid has decreased the pressure. As a result most of the tissue fluid is reabsorbed by osmosis .

42
Q

How else can tissue fluid be reabsorbed?

A

Through the lymphatic system where lymph is moved by the contraction of skeletal muscles. The fluid is then reintroduced into the blood system through ducts.

43
Q

What can happen if you do not move for a long time and why?

A

Lymph moves from the contraction of skeletal muscles. If muscles do not contract then the lymph gravitates downwards and will accumulate at the ankles. This results in swollen ankles.

44
Q

How could a lack of protein in the diet result in problems with tissue fluid?

A

Less amino acids in the blood leads to a less negative water potential at the veinous end of the capillary and as a result less tissue fluid is reabsorbed by osmosis. Tissue fluid then accumulates.

45
Q

Why is there a more negative water potential at the veinous end of the capillary?

A

Though solutes and water have moved out to produce tissue fluid in the arteriole end of the capillary. Some water and solutes remain in the capillary and in what remains there a bigger ratio of solutes to water then before, so water potential decreases.

46
Q

Where temperature is relatively high would the dissociation curve be more right or left? Higher affinity to oxygen or lower?

A

Lower affinity and more to the right because higher temperature means more respiration is occurring, releasing more CO2 and more oxygen is needed.

47
Q

Where pH is relatively high would the dissociation curve be more right or left? Higher affinity to oxygen or lower?

A

Higher affinity and more to the left because higher pH means less CO2 and less lactic acid is present meaning respiration is not occurring so oxygen does not need to be released readily.

48
Q

What’s the definition of Transpiration

A

The evaporation of water through the leaves via the stomata

49
Q

Whats Cohesion

A

When water sticks together because they are polar and form hydrogen bonds between molecules

50
Q

What is transported in the xylem?

A

Mineral ions (non-organic) and water

51
Q

In what direction does water and ions get transported in?

A

Only goes up

52
Q

What is the structure of the xylem?

A

Hollow tube made up of dead cells meaning no cell walls b/n the cells and no organelles. The cell wall is made of cellulose and lignin.

53
Q

What is the xylem cell wall made up of?

A

Lignin and cellulose

54
Q

What is the advantage of the xylems structure

A

Dead hollow cells mean there is nothing inside the tube to slow down the transport of water and minerals. Cellulose in cell wall allows the xylem to be strong and rigid so it won’t burst under the pressure of water. Lignin is waterproof and strong preventing leakage of water.

55
Q

Explain the cohesion tension theory?

A

Transpiration of water through the stomata creates a lower pressure at the top of the xylem. This pressure difference creates tension and water is pulled up. Water moves up in a continuous column because of cohesion.

56
Q

What effects the rate of transpiration?

A

Temperature, light, Humidity and wind

57
Q

What two ways do water and minerals get to the xylem?

A

1) Cell wall pathway- water moves through cells wall only. This is fast but dangerous.
2) Cytoplasmic pathway- water moves through cytosplasm of each cell having to cross selectively permeable membrane many times. This takes longer but is safer.

58
Q

What’s the structure of Phloem?

A

Living cells. Sieve tube elements stacked ontop, filled with cytoplasm. Between each element is a sieve plate. Each sieve element has its own companion cell.

59
Q

What is translocation?

A

The transport of organic substances in the phloem from source to sink

60
Q

What and where is a source?

A

Where glucose is produced, e.g leaves (where photosynthesis takes place)

61
Q

What is a sink?

A

Where glucose is transported to/ needed?

62
Q

Where could a sink be and for what purpose?

A

The root- for storage of insoluble starch.

Growing shoot- Glucose for respiration to produce ATP and help grow.

63
Q

Why is glucose converted to sucrose for transport in the phloem?

A

Sucrose is less reactive than glucose because it is a non-reducing sugar so will be transported for longer without reacting.

64
Q

What is the name of the theory for the translocation?

A

Mass Flow Theory

65
Q

How does sucrose get transported into the phloem?

A

Photosynthesising cells produce glucose which is converted to sucrose. High conc gradient of sucrose in the cell and low in companion cell so sucrose moves down conc gradient by facilitated diffusion. H+ ions are actively transported into the cell wall and the diffused into cytoplasm bringing sucrose with it.

66
Q

From the phloem how does sucrose get to the sink?

A

At the source end, there a very negative water potential so water from the xylem moves into the phloem by osmosis. This creates a high pressure. At the sink end sucrose is actively transported out of the phloem making the water potential more negative. As a result water moves out of phloem by osmosis too and the pressure decreases. The difference in pressure at source and sink makes the sucrose flow.

67
Q

How does ringing support mass Flow theory

A

the phloem is removed and swelling occurs at the source side and death occurs below at sink source. This show organic substances is transported via phloem.

68
Q

How does Aphids support Mass Flow Theory

A

Aphids feel from the phloem using their needle mouth piece. When you remove the body sap flows out of their mouth part. Flowing out = Pressure and sap illustrates the phloem transports organic substances.

69
Q

How does using radio active isotopes support Mass Flow Theory

A

If a plant only has access to Carbon-14 and you x ray the plant, Carbon-14 will appear in the phloem because the carbon has been incorporated into the organic substances e.g Glucose

70
Q

Give evidence against the Mass Flow theory

A

Some substances flow faster than others and we don’t know why.
Unknown why sieve plates are present, if anything would hinder the flow of substances.

Biology AQA A Level (15 decks)

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