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Biology year 1 > 7.0 Mass Transport > Flashcards

7.0 Mass Transport Flashcards

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1
Q

What type of molecule is haemoglobin?

A

Protein

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2
Q

How many polypeptide chains make up a haemoglobin molecule?

A

4

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3
Q

What does haemoglobin transport?

A

Oxygen

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4
Q

What is the primary structure of haemoglobin?

A

The order of amino acids in the polypeptide chains

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5
Q

What is the secondary structure of haemoglobin

A

The coiling of the polypeptide chains into a helix

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6
Q

What is the tertiary structure of haemoglobin?

A

The folding of the polypeptide chains into a precise shape

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7
Q

What is the quaternary structure of a haemoglobin?

A

The linking of the 4 polypeptide chains into an almost spherical molecule. Each polypeptide also has an associated haem group

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8
Q

What ion does a haem group contain?

A

Fe2+

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9
Q

How many oxygen molecules does each Fe2+ ion combine with?

A

1 oxygen per Fe2+

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10
Q

How many oxygen molecules can a molecule of haemoglobin carry in humans?

A

4m one per haem group, 1 haem group in a polypeptide chain, 4 polypeptide chain in a haemoglobin molecule

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11
Q

What is the name given to the process in which haemoglobin binds to oxygen?

A

Loading or associating

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12
Q

What is the name given to the process in which oxygen is released from a haemoglobin molecule?

A

Unloading or dissociating

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13
Q

What does affinity mean with respect to haemoglobin?

A

The chemical attraction between the haemoglobin and oxygen

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14
Q

If haemoglobin has a high affinity for oxygen, what does this mean?

A

Easier to associate, harder to dissociate

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15
Q

If haemoglobin has a low affinity, what does this mean?

A

Harder to associate, easier to dissociate

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16
Q

To be good at transporting oxygen, what 2 characteristics must haemoglobin have?

A

It must readily associate with oxygen where gas exchange occurs. it must readily dissociate from oxygen in respiring tissues which require it

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17
Q

How does haemoglobin change its affinity for oxygen?

A

It will change shape when in the presence of
certain molecules (e.g. carbon dioxide). If
present, the carbon dioxide changes the shape, so
the oxygen nolonger fis as well, and is easily
disassociated

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18
Q

What do we mean by partial pressure?

A

The pressure exerted by one component of a mixture of gases, if it alone occupied the volume. Eg: atmospheric pressure is 100KPa, oxygen is 21% of the atmosphere, so its partial pressure is 21KPa

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19
Q

What does a dissociation curve represent?

A

it is a graph referring to the partial pressure of oxygen, and how saturated the haemoglobin is with oxygen

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20
Q

What shape does the oxygen dissociation curve take?

A

S

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21
Q

Why does the oxygen dissociation curve increase slowly to begin with?

A

The shape of the haemoglobin molecule makes binding the first oxygen molecule difficult

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22
Q

Why does the oxygen dissociation curve increase sharply after a slow beginning>

A

The first oxygen molecule to bind changes the shape of the quaternary structure, this makes binding of subsequent molecules easier

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23
Q

Why does the oxygen dissociation curve increase slowly at the end of the graph?

A

Probability. It is easier for the molecules to bind,
but the likelyhood of the 4th oxygen molecule to
find an empty bionding site is less likely.

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24
Q

What is the name given to the increase in ease of binding for the other oxygen molecules?

A

Positive cooperativity

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25
Q

If an oxygen dissociation curve is shifted to the left does that affect the affinity for oxygen?

A

Higher affinity for oxygen, loads more readily, unloads less readily

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26
Q

If an oxygen dissociation curve is shifted to right does that affect the affinity for oxygen?

A

Lower affinity for oxygen, loads less readily and unloads more readily

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27
Q

What affect does carbon dioxide have on the affinity of haemoglobin?

A

The higher the concentration of carbon dioxide, the lower the affinity of haemoglobin to oxygen. Haemoglobin releases oxygen more readily

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28
Q

What effect does a lower concentration of carbon dioxide have on the oxygen dissociation curve?

A

Shifts the curve to the left

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29
Q

What is the name given to the shifting of the oxygen dissociation curve due to carbon dioxide?

A

The Bohr effect

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30
Q

What affect does a higher concentration of carbon dioxide have on the oxygen dissociation curve?

A

Shifts it to the right

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31
Q

What effect does the Bohr effect have at the gas exchange surface?

A

Low carbon dioxide concentrations. Affinity of
haemoglobin for oxygen is increased, curve is
shifted to the left

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32
Q

What effect does the Bohr effect have at the respiring tissues?

A

High carbon dioxide concentrations. Affinity of
haemoglobin for oxygen is decreased, curve is
shifted to the right.

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33
Q

Why does the carbon dioxide cause the haemoglobin to lose oxygen more readily?

A

Dissolved carbon dioxide is acidic. The low pH
causes the haemoglobin to change shape.

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34
Q

How might the oxygen dissociation curve appear for an animal adapted to live in an area with a low partial pressure of oxygen?

A

They would require haemoglobin with a higher
oxygen affinity, so the curve would be further to
the left

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35
Q

Why do large organisms require a transport system?

A

Diffusion is fast enough for short distances, but
large organisms need to transport nutrients over a
greater distance

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36
Q

Why are specialist exchange surfaces required in large organisms?

A

Large organisms require a large amount of
nutrients and create a large amount of waste.
This requires greater surface area than the
surface of the organism creates.

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37
Q

What happens to the surface area to volume ratio as the size of an organism increases?

A

The surface are to volume ration decreases.

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38
Q

What two factors determine whether an organism requires a specialised transport medium or a pump to circulate it?

A

The surface area to volume ratio and the
activeness.

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39
Q

What are the main features of all transport systems?

A

A suitable medium (e.g. blood);
A form of mass transport to move the medium
great distances;
A closed system of branching vessels;
A mechanism for moving the medium in the
vessels by pressure differences.
A way of controlling the direction of mass
transport (e.g. valves)
A way of controlling the flow of medium to suit
changing needs of the organism
A mechanism to control the mass flow of water
or gases. (E.g. intercostal muscle and diaphragm)

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40
Q

How do animals move their transport medium around their bodies?

A

Muscular contraction, either body muscles or
specialised pump (heart).

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41
Q

How do plants move their transport medium?

A

Passive process such as evaporation:

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42
Q

How is the heart described in terms of a pump?

A

A double pump

43
Q

What does the left side of the heart deal with?

A

Oxygenated blood from the lungs

44
Q

What does the right side of the heart deal with?

A

Deoxygenated blood from the body

45
Q

What are the two chambers that each side of the heart has?

A

Atrium and a ventricle

46
Q

What is the structure and role of the atria?

A

Thin walled and elastic, stretches as blood enters

47
Q

What is the structure and role of the ventricles?

A

Thick muscular wals to pump blood a good
distance (Lung or body)

48
Q

Why is the heart a double pump system?

A

As the blood flows through the cappilaries of the
lungs, there is a massive drop in pressure. This
would decrease the speed at which the blood
would flow through the rest of the body.

49
Q

What valve separates the left atrium and ventricle?

A

Left atrioventricular (bicuspid) valve

50
Q

What valve separates the right atrium and ventricle?

A

Right atrioventricular (tricuspid) valve

51
Q

Which chamber has the thickest walls and why?

A

Left ventricle because it has to pump blood
through the aorta at high pressure all round the
body

52
Q

What supplies the blood to the heart?

A

Coronary arteries

53
Q

What happens if the coronary arteries are blocked?

A

Myocardial infarction / heart attack as the muscle
cells have no oxygen so die as are unable to
respire aerobically.

54
Q

What is the contraction of the atria known as?

A

Atiral systole

55
Q

What is the relaxation of the heart called?

A

Diastole

56
Q

What is the contraction of the ventricles known as?

A

Ventricular systole

57
Q

What is the main job of the valves?

A

Prevent backflow of blood

58
Q

How do atrioventricular valves close?

A

As the ventricles contract, the ventrical pressure
exceeds atrial pressure.

59
Q

Where are the semilunar valves?

A

In the aorta and pulmonary artery

60
Q

How do the semilunar valves close?

A

When the elastic walls of the arteries recoil,
causing the pressure to exceed that of the relaxed ventricle. This forces blood through the artery.

61
Q

What are pocket valves?

A

These are valves located through the veinous
system.

62
Q

How do pocket valves close?

A

When the skeletal muscles contract, and the
veins are squeezed, the valves only allow blood
to flow towards the heart

63
Q

How do you calculate cardiac output?

A

heart rate x stroke volume

64
Q

What are the four type of blood vessel?

A

Arteries;
Arterioles;
Capillaries;
Veins

65
Q

What is the second most inner layer found in both arteries and veins called?

A

Elastic layer

66
Q

What is one adaptation of arteries which allows them to withstand high pressures?

A

Thick elastic tissue which allows them to stretch and recoil

67
Q

Which blood vessel carries blood from the heart to the body?

A

Aorta

68
Q

Which blood vessel carries blood from the body to the heart?

A

Vena cava

69
Q

Which blood vessel carries blood from the body to the kidneys?

A

Renal artery

70
Q

Which blood vessel carries blood from the kidneys to the vena cava?

A

Renal vein

71
Q

Which blood vessel carries blood from the heart to the lungs?

A

Pulmonary artery

72
Q

Name three substances found within tissue fluid

A

glucose
amino acids
fatty acids
ions in solution
oxygen.

73
Q

Describe how tissue fluid is returned to the circulatory system?

A

1 - Loss of tissue fluid causes a drop in
hydrostatic pressure
2 - Therefore at the venous end of the cappillary
network pressure is lower than the tissue fluid
outside
3 - Fluid is forced back in
4 - Also plasma which has lost water has a lower
water potential
5 - water moves from tissue fluid down a water
potential gradient

74
Q

How does water move up the stem?

A

Cohesion-tension

75
Q

How is water lost through a leaf?

A

Water is lost through a stomata

76
Q

How is water lost through the stomata?

A

Diffusion as the humidity of the atmosphere is lower than inside the leaf

77
Q

How does water move through the cells of a leaf?

A

Mesophyll cells lose water through evaporation.
This lowers their water potential
This causes movement of water via osmosis from
neighbouring cells. due to water potential
difference.

78
Q

How does water move up the stem in the xylem?

A

Water evaporates from the mesophyll causing
evaporation
The hydrogen bonds between water molecules
cause cohesion
Water makes an continuous chain from the
mesophyl down the xylem
The loss of water draws up new water molecules
- transpiration pull

79
Q

What is cohesion-tension theory?

A

The idea that the xylem is under tension, as the
pull from transpiration puts them undernegative
pressure.

80
Q

What is the evidence that supports cohesion-tension theory?

A

Change in the diameter of tree trunks based on
the rate of transpiration
If air enters the xlem, transpiration no longer
occurs as there is no continuous column of water
Water doesn’t leak out if the xylem is broken.
The negative pressure draws air in instead.

81
Q

Why is transpiration pull a passive process?

A

It occurs due to evaporation, it requires no
metabolic energy

82
Q

Where does the energy come from to drive the process of transpiration?

A

The sun

83
Q

When talking about the movement of water in plants, what is the cell wall pathway?

A

The movement of water around the cells, through
the cell walls (water doesn’t enter the cells.

84
Q

When talking about the movement of water in plants, what is the cytoplasmic pathway?

A

The movement of water through the cells via
osmosis as the water potential changes.

85
Q

Does sucrose affect water potential and if so how does the plant combat this?

A

Lowers water potential in the phloem sieve tubes,
water moves from the xylem to sieve tubes.

86
Q

What is a potometer?

A

A piece of equipment used to measure the
movement of water into a plant

87
Q

What is it that moves in a potometer?

A

Water moves through the potometer, this is
observed by trapping an air bubble than is drawn
through a capillary tube.

88
Q

Why is the plant to be investigated, cut underwater?

A

So as not to get air trapped in the xylem vessels

89
Q

What is measured when using a potometer?

A

The movement of a trapped air bubble along a
capillary tube, and the time taken. Then the
volume of water taken in by the plant can be
calculated, and the time taken used to calculate
the rate of uptake as well.

90
Q

How does sucrose enter the sink from the phloem?

A

Active transport

91
Q

How is sucrose moved from the source to the sieve elements?

A

1- Diffuses down the concentration gradient by
facilitated diffusion into companion cells
2 - H+ ions actively transported out of
companion cells
3 - H+ ions and sucrose molecules are
transported into seive tube elements by co-
transport

92
Q

How is sucrose moved through the sieve elements?

A

1 - Sucrose that moves in at the source decreases
water potential
2 - Water moves in from the xylem
3 - At the sinks, sucrose moves into the respiring
cells, as does water
4 - This creates a hydrostatic pressure difference,
so the sucrose solution is forced from source to
sink

93
Q

How is sucrose moved from the sieve elements to the storage or sink cells?

A

Active transport

94
Q

Why is mass flow described as passive?

A

It does not use metabolic energy to directly move
the substances

95
Q

Is translocation active or passive, why?

A

It is active, as it is driven by the active transport
of sugars.

96
Q

In a woody stem, what lies just under the bark?

A

The phloem

97
Q

What happens in a ringing experiment?

A

A complete ring of bark and phloem is removed
from the stem.

98
Q

What would you observe after a ringing experiment?

A

There is a swollen region in the bark just above
the where the ring of stripped stem is.

99
Q

What happens to the parts of a plant above and below the stripped area of bark in a ringing experiment?

A

The non-photosynthetic parts below the ring start
to die. those above stay alive.

100
Q

How does removing the phloem affect the plant? What does it mean?

A

Sugars accumulate above the ring causing the
swelling.
The interruption of the sugers cause the parts
below the ring to die.
It shows that the pholem not the xylem is
involved in the movement of sugars.

101
Q

What is an isotope?

A

An element with the same number of protons and
electrons, but a different number of neutrons.

102
Q

What are radioactive isotopes used for in plant investigations?

A

They can be used to trace the moevement of
these iosotopes and the substances they become
through the plant

103
Q

What is an example of a radioactive isotopes used? What happens to it in a plant?

A

14C is different to typical 12C. It can be
converted to CO2 which is then used in the plant
to create sugars.

104
Q

What can be used to identify the presence of the radioisotopes?

A

X-ray film. it will be blackened when exposed to the radiation

Biology year 1 (10 decks)

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