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AQA AS BIOLOGY 2015+ > 3 Mass transport > Flashcards

3 Mass transport Flashcards

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1
Q

Haemoglobin

A

protein molecules with a quaternary structure

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2
Q

primary structure

A

seqeuence of amino acids in the four polypeptide chains

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3
Q

secondary structure

A

each polypeptide chain is COILED into a helix

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4
Q

tertiary structure

A

each polypeptide chain is FOLDED into a PRECISE SHAPE

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5
Q

quaternary structure

A

all 4 polypeptide chains linked together to form an almost spherical molecule

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6
Q

haem group

A

contains ferrous/ fe2+ ion, each of which can combine with a single O2 so therefore 4 O2 molecules can be carried by a single haemoglobin molecule

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7
Q

Loading

A

aka Associating- when heamoglobin bindes with oxygen.

occurs in the lungs.

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8
Q

unloading

A

aka dissociating- when haemoglobin releases its oxygen .

takes place in the tissue.

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9
Q

high affinity

A

hb with high affinity takes up oxygen more easily but releases it less easily.

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10
Q

low affinity

A

hb with low affinity for oxygen takes it up less easily but release it more easily.

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11
Q

role of haemoglobin

A

to transport oxygen

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12
Q

how is hb efficient at transporting o2?

A
  • readily associates with oxygen at the surface where gas exchange takes place.
  • readily dissociates from oxygen at the tissue requiring it
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13
Q

Can hb change its affinity?

A

Yes, because it changes its shape in the presence of certain substances eg CO2 where hb binds moreloosely to O2 so oxyugen is released.

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14
Q

Conditions at gas exchange surfaces

A

1) O2 concentration is high
2) CO2 concentration is low
3) affinity is high so oxygen is associated

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15
Q

conditions at respiring tissue

A

1) O2 concentration is low
2) CO2 concentration is high
3) affinity is low so oxygen is dissociated

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16
Q

why are there different types of hb affinity?

A

> each species have hb with diff amino acid sequence
therefore diff quaternary and tertiary structures
therefore diff oxygen binding properties
due to their structures, some have high affinity for O2 and some have low affinity for O2

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17
Q

Oxygen dissociation curve

A
  • they show the affinity of haemoglobin for oxygen

the shape of one type of hb molecule can change under different conditions so there are many diff oxygen dissociation curves

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18
Q

what do oxygen dissociation curves show?

A

Oxygen dissociation curves show the relationship between oxygen levels (as partial pressure) and haemoglobin saturation

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19
Q

Cooperative binding

A

1st binding: Q structure changes so Hb changes shape.

  • makes it easier for other subunits to bind to an O2.
  • smaller increase of partial presuure needed to bind 2nd molecule.
  • Binding of 4th is harderbevause maj or binding sites=full so it’s less likely for s single O2 to find am empty site to bind to.
20
Q

OxD curve more to the left

A

greater affinity of hb

loading=easier

21
Q

Bohr effect

A

the greater the conc of CO2, the more readily the Hb unloads the oxygen.

22
Q

behaviour of hb at gas exchange surface (lungs)

A 
>low co2
>affinity for O2 increased
>high O2 in lungs
>oxygen more readily loaded by hb
curve more to the left
****opposite at respiring tissue/muscles
23
Q

effect of CO2 on hb

A

dissolved carbon dioxide is acidic and the low pH causes hb to change shape

24
Q

the more active a tissue, the more O2 is unloaded. why?

A 
high rate of respiration
more co2
lower ph
shape change
low affinithy
O2 unloaded more readily
more O2 available for respiration
25
Q

overall saturation of hb @ atmospheric pressure

A

97%

as not all hb molecumes are loeaded with 4 oxygen molecules

26
Q

when partially filled hb reaches tissue with low respiratory rate..

A

only 1 oxygen molecule is released

27
Q

saturation of hb of blood returning to lungs

A

75%

28
Q

how many oxygens released at highly respiring tissue?

A

3

29
Q

species of animals with low partial pressure of oxygen

A

have hb with higher affinity of oxygen with an OxD curve to the left.

30
Q

feature of transport system

A

> medium to carry material eg blood (liquid) or air (gas)
a form of mass transport- medium should be able to be moved in bulk and over large distances
mechanism for mass flow in 1d eg valves

31
Q

circulatory system in mammals

A

closed, (blood is confined to vessels) and double (passes through the heart for both the 2 complete circuits of the body).

32
Q

pressure of blood passing through lungs

A

reduced

33
Q

substances reach rest of body quickly because..

A

heart pumps it the second time

34
Q

vessels in mammals

A

arteries
veins
capillaries

35
Q

substance’s journey to cells is via

A

diffusion aka from blood cell to body cell

36
Q

why is diffusion from blood cell to body cell rapid?

A

large surface area
short diffusion pathway
steep diffusion gradient

37
Q

the heart

A

a muscular organ in the thoracic cavity behind the sternum

38
Q

2 pumps in the heart

A

left- oxygenated blood from the lungs

right- deoxygenated blood from the body

39
Q

each pump of the heart has 2 chambers, which are..

A

atrium

  • thin walled
  • elastic
  • stretches as it collects blood

ventricle

  • thick
  • muscular
  • contracts strongly to send blood to body or lungs
40
Q

why are 2 pumps nec. in the heart?

A

pressure is lost when blood moves through tiny capillaries in the lungs in order to present a large surface area for the exchange of the gases

41
Q

right ventricle

A

pumps blood only to the lungs

thinner muscular wall than left ventricle

42
Q

left ventricle

A

pums blood to the rest of the body as it has strng contraction, creating enough pressure.
thick muscular walls

43
Q

between the atria and ventricles

A

left atrioventricular valve
right atrioventricular valve
prevent the backflow of blood into th atria when the ventricles contract

44
Q

aorta

A

connected to the left ventricle

carries oxygenated blood to the body exc the lungs

45
Q

vena cava

A

connected to the right atrium

brings deoxygenated blood back from the body tissue exc the lungs

46
Q

pulmonary artery

A

connected to the right ventricle and carries deoxygenated blood (unusual for arteries) to the lungs to be replenished with O2 and to get rid of co2

47
Q

pulmonary vein

A

connected to the left atrium and brings oxygenated blood (unusual for veins) to the heart form the lungs

AQA AS BIOLOGY 2015+ (10 decks)

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