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biology > 3.2 - adaptations for transport > Flashcards

3.2 - adaptations for transport Flashcards

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1
Q

describe the vascular system of insects

A
  • open circulatory system
  • dorsal-tube shaped heart
  • respiratory gases not carried in blood
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2
Q

what’s an open circulatory system

A
  • transport medium pumped by heart not contained in vessels, but moves freely
  • transport fluid comes into direct contact w/ cells
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3
Q

describe the vascular system of earthworms

A
  • vascularisation
  • closed circulatory system
  • respiratory gases carried in blood
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4
Q

what’s a closed circulatory system

A
  • blood pumped by heart contained in blood vessels
  • blood doesn’t come into direct contact w/ cells
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5
Q

advantages of a closed circulatory system

A
  • blood pressure can be maintained
  • blood supply to different organs can vary
  • lower volumes of transport fluid required
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6
Q

what type of circulatory system do fish have

A

single circulatory system

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7
Q

what’s a single circulatory system

A
  • blood travels one circuit
  • blood flows through heart + pumped around body before retuning to heart
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8
Q

what type of circulatory system do mammals have

A

double circulatory system

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9
Q

what’s a double circulatory system

A
  • blood flows through heart twice in 2 circuits
  • blood pumped from heart to lungs before returning to heart, then pumped around body, after which returning to heart again
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10
Q

what are the benefits of a double circulatory system

A
  • maintains blood pressure around whole body
  • uptake of O2 more efficient
  • delivery of O2 + nutrients more efficient
  • blood pressure can differ in pulmonary + systemic circuits
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11
Q

describe the double circulatory system in humans

A

blood flows through heart twice in 2 circuits:
- pulmonary circuit
- systemic circuit

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12
Q

name the 4 chambers of the mammalian heart

A
  • left atrium
  • right atrium
  • left ventricle
  • right ventricle
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13
Q

describe the pathway of blood around the body, naming the structures of the heart

A

pulmonary vein → left atrium → left ventricle → aorta → body → vena cava → right atrium →. right ventricle → pulmonary artery → lungs

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14
Q

where are the atrioventricular valves found + what’s their function

A
  • found between atria + ventricles
  • prevents backflow of blood from ventricles into atria
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15
Q

what are the 2 types of atrioventricular valves

A
  • bicuspid (left side)
  • tricuspid (right side)
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16
Q

where are the semilunar valves found + what’s their function

A
  • found between ventricles + arteries
  • prevents backflow of blood from arteries into ventricles
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17
Q

name the 5 types of blood vessel

A
  • arteries
  • arterioles
  • capillaries
  • venules
  • veins
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18
Q

describe the pathway of blood through the blood vessels

A

heart → arteries → arterioles → capillaries → venules → veins → heart

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19
Q

what’s the function of arteries

A

carries blood away from heart to tissues, under high pressure

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20
Q

relate the structure of arteries to their function

A
  • thick muscular walls to handle high pressure w/out tearing
  • elastic tissue allows recoil to prevent pressure surges
  • narrow lumen to maintain pressre
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21
Q

what’s the function of veins

A

carry blood towards heart under low pressure

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22
Q

relate the structure of veins to their function

A
  • thin walls due to lower pressure
  • valves to ensure blood doesn’t flow backwards
  • less muscular + elastic tissue as they dont have to control blood flow
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23
Q

what’s the function of capillaries

A

form large network through tissue of body + connect arterioles to venules

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24
Q

relate the structure of capillaries to their function

A
  • walls only one cell thick, short diffusion pathway
  • v narrow, can permeate tissues + red blood cells can lie flat against wall, reducing diffusion distance
  • numerous + highly branched, providing large SA
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25
Q

what’s the function of arterioles

A

connect arteries + capillaries

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26
Q

what’s the function of venules

A

connect capillaries + veins

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27
Q

relate the structure of arterioles + venules to their function

A
  • branch off arteries + veins to feed blood into capillaries
  • smaller than arteries + veins so change in pressure is more gradual as blood flows to capillaries
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28
Q

what’s the cardiac cycle

A
  • sequence of events involved in one complete contraction + relaxation of heart
  • 3 stages: atrial systole, ventricular systole, diastole
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29
Q

describe what happens in ventricular diastole

A
  1. heart is relaxed
  2. blood enters atria, increasing pressure + pushing open AV valves
  3. allows blood to flow into ventricles
  4. pressure in heart is lower than in arteries, so SL valves remain closed
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30
Q

describe what happens in atrial systole

A
  1. atria contract, pushing any remaining blood into ventricles
  2. AV valves pushed fully open
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31
Q

describe what happens in ventricular systole

A
  1. ventricles contract
  2. pressure in ventricles increases, closing AV valves to prevent backflow + opening SL valves
  3. blood flows into arteries
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32
Q

why is cardiac muscle described as myogenic

A

it initiates its own contraction w/out outside stimulation from nervous impulses

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33
Q

explain how the heart contracts

A
  1. SAN initiates + spreads impulse across atria, so they contract
  2. AVN receives, delays, + then conveys impulse down bundle of his
  3. impulse travels into purkyne fibres which branch across ventricles, so they contract from bottom up
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34
Q

what’s an electrocardiogram (ECG)

A

graph showing electrical activity in heart during cardiac cycle

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35
Q

explain the characteristic patterns displayed on a typical ECG

A

P wave - depolarisation of atria in atrial systole
QRS wave - depolarisation of ventricles during ventricular systole
T wave - repolarisation of ventricles in ventricular diastole

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36
Q

describe the structure + function of erythrocytes

A
  • type of blood cell that’s anucleated + biconcave
  • contains haemoglobin which enables the transport of O2 + CO2 to and from tissues
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37
Q

what’s plasma

A
  • main component of blood (yellow liquid) that carries red blood cells cells
  • contains proteins, nutrients, mineral ions, hormones, dissolved gases + waste
  • distributes heat
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38
Q

describe the role of haemoglobin

A

present in red blood cells
O2 molecules bind to haem groups + are carried around the body, then released where they are needed in respiring tissues

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39
Q

how does partial pressure of O2 affect oxygen-haemoglobin binding

A

haemoglobin has variable affinity for O2 depending on partial pressure of O2, p(O2):
- at hig p(O2), oxygen associates to form oxyhaemoglobin
- at low p(O2), oxygen dissociates to form deoxyhaemoglobin

40
Q

what do oxyhaemoglobin dissociation curves show

A

saturation of haemoglobin w/ O2 (%) plotted against partial pressure of O2 (kPa)
curves further to left show that haemoglobin has higher affinity for O2

41
Q

explain the shape of oxyhaemoglobin dissociation curves

A

sigmoidal curve (s-shaped):
- when first O2 molecule binds, it changes the tertiary structure of haemoglobin so its easier for second + third molecules to bind
- third molecule changes tertiary structure of haemoglobin so its more difficult for fourth molecule to bind

42
Q

how does fetal haemoglobin differ from adult haemoglobin

A

has higher affinity for O2 than adult haemoglobin due to presence of 2 different subunits that allow O2 to bind more readily

43
Q

why is higher affinity of fetal haemoglobin important

A

enables fetus to obtain O2 from mothers blood

44
Q

compare dissociation curves of adult + fetal haemoglobin

A

fetal curves to left
at same partial pressure, % O2 saturation is greater

45
Q

predict the shape of the dissociation curves of animals adapted to low O2 level habitats

A
  • haemoglobin has greater affinity for O2
  • haemoglobin saturated at lower p(O2)
  • dissociation curves to left
46
Q

how is CO2 carried from respiring cells to lungs

A
  • transported in aqueous solution in plasma
  • as hydrogen carbonate ions in plasma
  • carried as carbaminohaemoglobin in blood
47
Q

what’s the chloride shift

A
  • process by which chloride ions move into erythrocytes for hydrogen carbonate ions which diffuse out of erythrocytes
  • one to one exchange
48
Q

whys the chloride shift important

A

maintains electrochemical equilibrium of cell

49
Q

what’s the function of carbonic anhydrase

A

catalyses the reversible reaction between water + CO2 to produce carbonic acid

50
Q

equations to show the formation of hydrogen carbonate ions in plasma

A

carbonic anhydrase enzyme catalyses:
CO2 + H2O ⇌ H2CO3 (carbonic acid)
carbonic cider dissociates:
H2CO3 ⇌ HCO3- (hydrogen carbonate ions) + H+

51
Q

state the bohr effect

A

loss of affinity of haemoglobin for O2 as the partial pressure of CO2 increases

52
Q

explains he role of carbonic anhydrase in the bohr effect

A
  • carbonic anhydrase present in red blood cells
  • catalyses reaction of CO2 + water to form carbonic acid, dissociating to produce H+ ions
  • H+ ions combine w/ haemoglobin to form haemoglobinic acid
  • encourages O2 to dissociate from haemoglobin
53
Q

what’s tissue fluid

A
  • fluid surrounding cells of animals
  • same composition as plasma but docents contain red blood cells or plasma proteins
54
Q

describe the different pressure involved in formation of tissue fluid

A
  • hydrostatic pressure = higher at arterial end of capillary than venous end
  • oncotic pressure = changing water potential of capillaries as water moves out, induced by proteins in plasma
55
Q

how is tissue fluid formed

A

as blood pumped through increasingly smaller vessels, hydrostatic pressure is greater than oncotic pressure, so fluid moves out of capillaries
then exchanges substances w/ cells

56
Q

why does blood pressure fall along capillary

A
  • friction
  • lower volume of blood
57
Q

what happens at venous end of capillary

A
  • oncotic pressure greater than hydrostatic pressure
  • fluid moves down water potential gradient back into capillaries
58
Q

where does some tissue fluid drain

A

into lymphatic system + eventually returns to blood

59
Q

define vascular bundle

A
  • vascular system in herbaceous dicotyledonous plants
  • consists of 2 transport vessels, xylem + phloem
60
Q

describe the structure + function of the vascular system in roots of dicotyledons

A

xylem arranged in X shape to provide resistance against force
phloem found as patches between arms
surrounded by endodermis, aiding water passage

61
Q

describe the structure + function of the vascular system in stem of dicotyledons

A

vascular bundles organised around central pith
xylem on inside of bundle providing support + flexibility
phloem on outside of bundle
cambium found between the 2

62
Q

what structure in plants adapted for uptake of water + minerals

A

root hair cell

63
Q

how is water taken up from soil

A
  • root hair cells absorb minerals by active transport, reducing water potential of root
  • water potential of root hair cells lower than that of soil
  • water moves into root by osmosis
64
Q

outline how plant roots adapted for absorption of water + minerals

A

plant roots composed of millions of root hair cells which have:
- long hairs extending from cell body, increasing SA for absorption
- many mitochondria producing energy for active transport of mineral ions

65
Q

state the 3 pathways by which water moves through root

A
  • apoplast pathway
  • symplast pathway
  • vacuolar pathway
66
Q

describe the apoplast pathway

A

water moves through intercellular spaces between cellulose molecules in cell wall
diffuses down water potential gradient by osmosis

67
Q

describe the symplast pathway

A

water enters cytoplasm through plasma membrane + moves between adjacent cells via plasmodesmata
water diffuse down water potential gradient by osmosis

68
Q

describe the vacuolar pathway

A

water enters cytoplasm through plasma membrane + moves between vacuoles of adjacent cells
water diffuses down water potential gradient by osmosis

69
Q

describe the structure + function of the endodermis

A
  • innermost layer of cortex of dicot root
  • impregnated w/ suberin which forms casparian strip
  • endodermal cells actively transport mineral ions into xylem
70
Q

what’s the function of the casparian strip

A
  • blocks apoplast pathway, forcing water through symplast route
  • enables control of movement of water + minerals across root + into xylem
71
Q

what molecule makes casparian strip waterproof

A

suberin

72
Q

relate the structure of xylem to its function

A
  • long, continuous column shade of dead tissue, allowing transport of water
  • containing bordered pits, allowing sideways movement of water between vessels
  • walls impregnated with/ lignin, providing structural support
73
Q

define transpiration

A
  • loss of water vapour from parts of plant exposed to air due to evaporation + diffusion
  • consequence of gaseous exchange; occurs when plant opens stomata to exchange O2 + CO2
74
Q

what’s the transpiration stream

A

flow of water from roots to leaves in plants, where its lost by evaporation to environment

75
Q

how does water move up stem

A
  • root pressure
  • cohesion tension theory
  • capillarity
76
Q

what is root pressure

A

force driving water into + up xylem by osmosis due to active transport of minerals into xylem by endodermal cells

77
Q

explain the cohesion tension theory

A
  • water molecules form H bonds w/ each other, causing them to ‘stick’ together
  • surface tension of water also creates sticking effect
  • as water lost through transpiration, more is raw n up stem from roots
78
Q

define capillarity

A

tendency of water to move up xylem, against gravity, due to adhesive forces preventing water column dropping back

79
Q

state the factors affecting the rate of transpiration

A
  • light
  • temperature
  • humidity
  • air movement
80
Q

how does temperature affect transpiration rate

A

higher temp increases random motion + rate of evaporation, increasing rate of transpiration

81
Q

how does light affect rate of transpiration

A

higher light intensity increases rate of photosynthesis, causing more stomata to open for gas exchange, increasing rate of transpiration

82
Q

how does humidity affect rate of transpiration

A

high humidity means water content of air next to leaf is high
reduces conc gradient, decreasing rate of transpiration

83
Q

how does air movement affect rate of transpiration

A

large amounts of air movement blow moist air away from leaves, creating steep concentration gradient, increasing rate of transpiration

84
Q

what’s a hydrophyte

A

plant adapted to live + reproduce in v wet habitats e.g: water lilies

85
Q

adaptations of hydrophytes allowing them to live in wet conditions

A
  • thin/absent waxy cuticle
  • stomata often open
  • wide, flat leaves
  • air spaces for buoyancy
86
Q

what’s a xerophyte

A

plant adapted to live + reproduce in dry habitats where water availability is low
e.g: cacti + marram grass

87
Q

adaptations of xerophytes allowing them to live in dry conditions

A
  • small/rolled leaves
  • densely packed mesophyll
  • thick waxy cuticle
  • stomata often closed
  • hairs to trap moisture
88
Q

what are mesophytes

A
  • terrestrial plants adapted to live in environments w/ average conditions + an adequate water supply
  • have feature that enable survival at unfavourable times of the year
89
Q

relate the structure of phloem to its function

A
  • sieve tube elements transport sugars around plant
  • companion cells designed for active transport of sugars into tubes
  • plasmodesmata allow communication + exchange of substances between sieve tubes + companion cells
90
Q

what are cytoplasmic strands

A

small extensions of cytoplasm between adjacent sieve tube elements + companion cells

91
Q

describe the function of cytoplasmic strands

A
  • allow communication + exchange of materials between sieve tube elements + companion cells
  • hold nucleus in place
92
Q

define translocation

A

movement of organic compounds in phloem, from sources to sink

93
Q

define translocation

A

movement of organic compounds in phloem, from sources to sink

94
Q

summarise the mass flow hypothesis of translocation

A
  • sugar loaded into sieve tubes via active transport
  • lowers water potential causing water to move in from xylem
  • hydrostatic pressure causes sugars to move towards sink
95
Q

give evidence for the mass flow hypothesis

A
  • sap released when stem is cut, must be pressure in phloem
  • sap exuding from stylet or aphid inserted into sieve tues provides evidence that sugars are carried in phloem
  • higher sucrose conc in leaves than roots
  • autoradiographs produced using CO2 labelled with/ radioactive carbon provide evidence for translocation in phloem
96
Q

what’s autoradiography

A

technique used to record distribution of radioactive material within a specimen

97
Q

what’s a potometer

A

apparatus used to measure water uptake from cut shoot

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