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mass transport Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

describe the structure of haemoglobin

A
  • globular
  • water soluble
  • 4 polypeptide chains
  • each chain carries a haem group
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2
Q

describe the role of haemoglobin

A
  • in red blood cells

- oxygen molecules bind to haem groups + are carried around the body to respiring tissues

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3
Q

name three factors affecting oxygen - haemoglobin binding

A
  • partial pressure / concentration of oxygen
  • partial pressure / concentration of carbon dioxide
    saturation of haemoglobin with oxygen
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4
Q

how does partial pressure of oxygen affect oxygen-haemoglobin binding?

A
  • as partial pressure of oxygen increases - affinity of haemoglobin for oxygen increases
  • so oxygen binds TIGHTLY to haemoglobin
    when partial pressure is LOW - oxygen is RELEASED from haemoglobin
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5
Q

how does partial pressure of carbon dioxide affect oxygen - haemolobin binding?

A
  • as partial pressure of carbon dioxide increases - conditions = ACIDIC so haemoglobin CHANGES SHAPE
  • affinity for haemoglobin decreases
  • oxygen released from haemoglobin
  • BOHR EFFECT
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6
Q

how does saturation of haemoglobin with oxygen affect oxygen - haemoglobin binding?

A
  • hard for first molecule to bind
  • once it does - changes shape so easier for 2nd and 3rd
    this = POSITIVE COOPERATIVITY
  • harder for 4th oxygen molecule to bind as low chance of finding empty binding site
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7
Q

why does oxygen bind to haemoglobin in the lungs?

A
  • high partial pressure of oxygen
  • low concentration of carbon dioxide - high affinity
    positive cooperativity
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8
Q

why is oxygen released from haemoglobin in respiring tissues?

A
  • low partial pressure of oxygen

high concentration of CO2 in respiring tissues - decreased affinity

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9
Q

how does carbon dioxide affect the position of an oxyhaemoglobin dissociation curve?

A
  • curve shifts to the right because haemoglobin’s affinity for oxygen decreases
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10
Q

relate structure of the atria to their function

A
  • atria are thin walled and elastic so can stretch when filled with blood
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11
Q

relate the structure of the ventricles to their function

A
  • thick + muscular walls
  • pump blood under high pressure
  • LEFT ventricle is THICKER as it has to pump blood all around the body
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12
Q

relate the structure of the arteries to their function

A
  • the arteries have thick walls to handle HIGH PRESSURE without tearing
  • muscular and elastic to control blood flow
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13
Q

relate the structure of the veins to their function

A
  • thin walls due to lower pressure
  • VALVES to ensure blood doesn’t flow backwards
  • less muscular and elastic tissue as they don’t have to control blood flow
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14
Q

describe what happens during cardiac diastole

A
  • heart = RELAXED
  • blood enters atria - increases pressure - pushes open atrioventricular valves
  • blood can flow to ventricles
  • pressure in heart is LOWER than in arteries - semilunar valves remain CLOSED
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15
Q

what happens during atrial systole?

A
  • atria CONTRACT

- pushing and remaining blood into the ventricles

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16
Q

what happens during ventricular systole?

A
  • ventricles CONTRACT
  • pressure increases - closing atrioventricular valves to prevent backflow
  • opening semi-lunar valves
    blood flows into the arteries
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17
Q

what does myogenic mean?

A

the heart’s contraction is initiated from within the muscle itself, rather than by nerve impulses

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18
Q

how is the structure of the capillaries suited to their function?

A
  • walls one cell thick - short diffusion distance
  • narrow - can permeate tissues and red blood cells can lie flat against the wall, effectively delivering oxygen to tissues
  • numerous + HIGHLY BRANCHED = large surface area
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19
Q

what is tissue fluid?

A
  • watery substance containing glucose, amino acids, oxygen and other nutrients
  • it supplies these to the cells and removes any waste materials
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20
Q

how is tissue fluid formed?

A
  • as blood is pumped through increasingly small vessels
  • hydrostatic pressure created
  • forces fluid out of the capillaries
  • bathes the cells then returns to the capillaries when hydrostatic pressure is low enough
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21
Q

how is water transported in plants?

A
  • xylem vessels
  • long, continuous columns
  • also provide structural support to the stem
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22
Q

explain the cohesion - tension theory

A

COHESION - hydrogen bonds between water molecules mean that they stick together
surface TENSION of the water also creates sticking effect
- so as water is lost through transpiration, more can be drawn up the stem

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23
Q

name the three components of phloem vessels

A

sieve tube elements
companion cells
plasmodesmata

24
Q

what is translocation?

A

the process whereby organic materials are transported around the plant

25
Q

what are the sieve tube elements

A

component of phloem vessel

- form a tube to transport sucrose in dissolved form of sap

26
Q

what are the companion cells

A

involved in ATP production for active loading of sucrose into sieve tubes

27
Q

evidence for mass flow hypothesis of translocation?

A
  • sap is released when a stem is cut so there must be pressure in phloem
  • higher conc of sucrose in leaves than in roots
28
Q

evidence against mass flow hypothesis of translocation

A
  • structure of sieve tubes seem to hinder mass flow

- not all solutes move at same speed

29
Q

describe ringing experiments to investigate transport in plants

A
  • bark and phloem of tree removed in a ring
  • leaving XYLEM behind
  • tissues above missing ring SWELL due to accumulation of sucrose
  • tissues below begin to die
  • sucrose must be transported in PHLOEM
30
Q

how can tracing experiments be used to investigate plant transport?

A
  • plants grown in presence of RADIOACTIVE CO2
  • this will be incorporated into plants sugars
  • using AUTORADIOGRAPHY we can see that areas exposed to radiation correspond to where PHLOEM is
31
Q

in humans where does oxygen association occur?

A

lungs

32
Q

in humans where does oxygen dissociation occur?

A

tissues

33
Q

what is positive cooperativity?

A

a smaller increase in the partial pressure or oxygen is needed for the oxygen to bind to the SECOND oxygen molecule

34
Q

why does the curve flatten off in an oxygen dissociation curve?

A

majority of binding sites occupied

less likely that a single O2 molecule will find empty one to bind to

35
Q

why is it hardest for first oxygen molecule to bind to haemoglobin?

A

shape of haemoglobin

four polypeptide subunits are CLOSELY UNITED

36
Q

common features of organisms transport systems

A
  • suitable medium to carry materials
  • transport medium moved in bulk over large distances
  • closed system of TUBULAR vessels which form BRANCHING network
37
Q

what type of circulatory system do mammals have?

A

a closed, double circulatory system

  • blood is confined to vessels and passes twice through heart per circuit)
38
Q

why does the blood pass through the heart twice in one circuit?

A
  • as blood is passed through lungs the pressure is REDUCED
  • low pressure would make circulation very slow
  • blood is RETURNED to heart to boost pressure before being circulated to other tissues
39
Q

name the two valves between the atria and ventricle which prevent BACKFLOW of blood into atria when ventricles contract

A
  • left atrioventricular - BICUSPID

- right atrioventricular - TRICUSPID

40
Q

what pumps blood away from the heart and into the arteries?

A

ventricles

41
Q

what are the vessels connecting the heart to the lungs called?

A

pulmonary vessels

42
Q

what is the aorta?

A

connected to left ventricle

carries oxygenated blood to all parts of body EXCEPT LUNGS

43
Q

what is the vena cava?

A

connected to right atrium

bring deoxygenated blood back from tissues in blood EXCEPT FOR LUNGS

44
Q

what is the pulmonary artery?

A

connected to right ventricle

carries deoxygenated blood to lungs

45
Q

what is the pulmonary vein?

A

connected to LEFT ATRIUM

bring oxygenated blood back from lungs

46
Q

what is the function of the coronary arteries?

A

supply oxygenated blood to tissues in the heart

47
Q

risk factors associated with cardiovascular disease

A

smoking
high blood pressure
diet
blood cholesterol

48
Q

equation to calculate cardiac output?

A

CO = heart rate x stroke volume

49
Q

define translocation

A

movement of organic molecules through sieve tubes from a source to a sink - requires energy

50
Q

why are sieve tube cells tall cylinders stacked end on end?

A

continuous flow of solutes

51
Q

why do sieve tube cells have perforated cell walls?

A

allow fast transport, doesn’t restrict large molecules

52
Q

why are sieve tube cells elongated?

A

fewer end walls to restrict flow

53
Q

why are sieve tube cell walls made of cellulose?

A

allows loading and unloading of solutes

54
Q

what is a source in mass flow?

A

cells that photosynthesise and make sugar

55
Q

what are sinks in mass flow?

A

part of plants that remove sugar from the phloem

56
Q

give some problems with the Mass Flow Theory

A
  • sucrose and AA move too quickly for passive transport
  • solutes can travel at different speeds
  • solutes can travel in different directions

biology (11 decks)

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