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Biology Unit 2 > 2.3 Adaptation in transport > Flashcards

2.3 Adaptation in transport Flashcards

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1
Q

Briefly 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 is an open circulatory system?

A

-transport medium pumped by the heart isn’t contained within vessels but moves freely
-transport fluid comes into direct contact with cells

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3
Q

Briefly describe the vascular system of earthworms

A

-vascularisation
-CLOSED circulatory system
-respiratory gases carried into blood

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4
Q

What is a closed circulatory system?

A

-blood pumped by the heart is contained within blood vessels
-blood doesn’t come into direct contact with the cells.

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5
Q

What are the advantages of a closed CS?

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 CS do fish have?

A

single CS

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7
Q

What is a single CS?

A

CS in which the blood travels through the heart once in one circuit
-blood flows through the heart and is pumped around the body before returning to heart

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8
Q

What type of CS do mammals have?

A

double CS

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9
Q

What is double CS?

A

-CS in which blood flows through the heart twice in 2 circuits
-blood is pumped from the heart to lungs before returning to heart
-its then pumped around body then returns to heart again

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10
Q

Whats the benefits of a double CS?

A

-maintains blood pressure around whole body
-uptake of o2 is more efficient
-delivery of o2 ad nutrients is more efficient
-blood pressure can differ in pulmonary and systematic circuits

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11
Q

Describe the double CS in humans

A

blood flows through heart twice in 2 circuits
1.pulmonary circuit
2.systematic circuit

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12
Q

Name 4 chambers of the mammalian heart

A

1.left atrium
2.right atrium
3.left ventricle
4.right ventricle

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13
Q

Describe the pathway of blood around the body

A
  1. pulmonary vein
    2.left artium
    3.left ventricle
    4.aorta
    5.body
    6.vena cava
    7.right atrium
    8.right ventricle
    9.pulmonary artery
    10.lungs
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14
Q

Where are the atrioventricular valves found and what’s their function?

A

-found between atria and ventricles
-prevent back flow of blood from ventricles into atria

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15
Q

What 2 types of atrioventricular valves are there?

A

1.bicuspid (left)
2.tricuspid (right)

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16
Q

Where are the semilunar valves found and what is their function?

A

-found between ventricles and arteries
-prevent back flow of blood from the arteries into ventricles

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17
Q

Name 5 types of blood vessels

A

-arteries
-arterioles
-capillaries
-venules
-veins

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18
Q

Describe the pathway of blood through the blood vessels

A

1.heart
2.arteries
3.arterioles
4.capillaries
5.venules
6.veins
7.heart

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19
Q

What is the function of arteries?

A

carry blood away from heart to the tissues under high pressure

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20
Q

Relate the structure of arteries to their function

A

-thick, muscular walls to handle pressure without tearing
-elastic tissue allows recoil to prevent pressure surges
-narrow lumen to maintain pressure

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21
Q

What is the function of the vein?

A

carry blood towards the 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
-require valves to ensure blood doesn’t flow backwards
-have less muscular and elastic tissue as don’t have to control blood flow

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23
Q

What is the function of capillaries?

A

form a large network through the tissues of body and connect the arterioles to venules

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24
Q

Relate structure of capillaries to their function

A

-walls one cell thick so short diffusion pathway
-very narrow, so can permeate tissues and RBC can lie flat against the wall, reducing diffusion distance
-numerous and highly branched that provides a large SA

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25
Q

What is function of arterioles?

A

connect arteries and capillaries

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26
Q

What is function of venules?

A

connect capillaries to veins

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27
Q

Relate the structure of arterioles and venules to their function

A

-branch off arteries and veins in order to feed blood into capillaries
-smaller than arteries and vein so change in pressure is more gradual as blood flows to capillaries

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28
Q

What is the cardiac cycle?

A

-sequence of evens involved in one complete contraction and relaxation of the heart
-3 stages
1.atrial systole
2.ventricular systole
3.diastole

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29
Q

What happens during ventricular diastole?

A

-heart is relaxed
-blood enters atria, increasing pressure and pushing open the AV valves
-allows blood to flow into ventricles
-pressure in heart is lower than in arteries so SL valves=closed

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30
Q

Describes what happens during atrial systole

A

-atria contracts, pushing remaining blood into ventricles
-AV pushed fully open

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31
Q

Describes what happens during ventricular systole

A

-ventricles contract
-pressure in ventricles increases, closing AV valves to prevent back flow
-opens SL valves
-blood flows into arteries

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32
Q

Why is cardiac muscle described as myogenic?

A

it initiates its own contraction without outside stimulation from nervous impulses

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33
Q

Explain how the heart contracts

A

-Sinoatrial node (SAN) initiates and spreads impulse across atria so contracts
-Atrioventricular node (AVN) receives, delays then conveys impulse down the bundle of His
-impulse travels into Purkyne fibres which branch across ventricles so contracts from bottom up

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34
Q

What is an electrocardiogram? (ECG)

A

graph showing electrical activity in heart during cardiac cycle

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35
Q

Explain the characteristics patterns displayed on a typical ECG

A

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

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36
Q

Describe role of haemoglobin

A

-present in RBC
-o2 molecules bind to haem groups and are carried around body then released where they are needed in respiring tissues

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37
Q

How does partial pressure of o2 affect oxygen haemoglobin binding?

A

haemoglobin has variable affinity for oxygen depending on partial pressure of oxygen p(o2)
-high p(o2), oxygen ASSOCIATES to form oxyhaemoglobin
-low p(o2), oxygen DISSOCIATES to form deoxyhaemoglobin

38
Q

Explain the shape of oxyhaemoglobin dissociation curves

A

SIGMOIDAL CURVE (s shape)
-first o2 molecule binds, it changes tertiary structure of haemoglobin so easier for 2nd and 3rd molecules to bind
-3rd molecule changes tertiary structure so more difficult for 4th to bind

39
Q

How does metal 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

40
Q

Why is the higher affinity of fetal haemoglobin vital?

A

enables the fetus to obtain o2 from mothers blood

41
Q

Compare the dissociation curve of adult and fetal haemoglobin

A

-FH dissociation curve to the LEFT
-at same p(o2), % of o2 saturation is greater due to fetal haemoglobin having higher affinity

42
Q

Predict the shape of the dissociation curves of animals adapted to low oxygen level habitats

A

-haemoglobin has a greater affinity for o2
-haemoglobin is saturated at a lower p(o2)
-dissociation curves to LEFT

43
Q

Describe the structure and function of erythrocytes

A

-type of blood cell that is anucleated and biconcave
-contains haemoglobin which enables the transport for o2 and co2 to and from tissues

44
Q

What is the chloride shift?

A

-process by which chloride ions move into erythrocytes in exchange for hydrogen carbonate ions which diffuse out of the erythrocytes
-one to one exchange

45
Q

Why is the chloride shift important?

A

maintains the electrochemical equilibrium of the cell

46
Q

What is the function of carbonic anhydrase?

A

catalyses the reversible reaction between water and co2 to produce carbonic acid

47
Q

State the Bohr effect

A

the loss of affinity of haemoglobin for o2 as the p(co2) increases

48
Q

What is tissue fluid?

A

-fluid that surrounds the cells of animals
-same composition as plasma but doesn’t contain RBC or plasma proteins

49
Q

Describe the different pressures involved in the formation of tissue fluid

A

HYDROSTATIC PRESSURE
-higher at arterial end of capillary than venous end
OSMOTIC PRESSURE
-changing water potential of capillaries as water moves out, induced by proteins in plasma

50
Q

How is tissue fluid formed?

A

-as blood is pumped through increasingly smaller vessels, HP is greater than OP so fluid moves out of capillaries
-it then exchanges substances with cells

51
Q

Why does blood pressure fall along the capillary?

A

-friction
-lower volume of blood

52
Q

What happens at the venous end of the capillary?

A

-osmotic pressure is greater than hydrostatic pressure
-fluid moves down its water potential gradient back into capillaries

53
Q

Where does some tissue fluid drain?

A

some tissue fluid drains into lymphatic system and returns to blood

54
Q

Define vascular bundle

A

-vascular system in herbaceous dicotyledonous plants
-consists of 2 transport vessels;
1. xylem
2.phloem

55
Q

Describe the structure and function of the vascular system in the roots of dicotyledons

A

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

56
Q

Describe the structure and function of the vascular system in the stem of dicotyledons

A

-vascular bundles organised around central pith
-xylem on inside of bundle to provide support and flexibility, phloem on outside
-cambium found between the 2

57
Q

Which structure in plants is adapted for the uptake of water and minerals

A

root hair cells

58
Q

How is water taken up from soil?

A

-root hair cells absorb minerals by AT reducing water potential of root
-water potential of RHC is lower than soil
-water moves into root via osmosis

59
Q

Outline how plant roots are adapted for the absorption of water and minerals

A

plant roots are composed of millions of root hair cells which have;
-long hairs that extend from cell body, increasing SA for absorption
-many mitochondria to produce energy for AT of mineral ions

60
Q

State 3 pathways which water moves via root

A
  1. apoplast pathway
    2.symplast pathway
    3.vacuolar pathway
61
Q

Describe the apoplast pathway

A

water moves in via intercellular spaces between cellulose molecules in cell wall. it diffuses down its water potential gradient by OSMOSIS

62
Q

Describe the symplast pathway

A

water enters cytoplasm via plasma membrane and moves between adjacent cells via plasmodesmata. water diffuses down its water potential gradient via OSMOSIS

63
Q

Describe the vacuolar pathway

A

water enters the cytoplasm via plasma membrane and moves between vacuoles of adjacent walls. water diffuses down its water potential gradient via OSMOSIS

64
Q

Describe the structure and function of the endodermis

A

-innermost layer of the cortex of a dicot root
-impregnated with the Suberin which forms casparian strip
-endodermal cells actively transported mineral ions into the xylem

65
Q

What is the function of the casparian strip?

A

-blocks apoplast pathway, forcing water through symplast route
-enables control of the movement of water and minerals across root into xylem

66
Q

What molecule makes the casparian strip waterproof?

A

suberin

67
Q

Relate the structure of the xylem to its functions

A

-long, continuous columns made of dead tissue allowing transportation of water
-contains bordered pits allowing sideways movements of water between vessels
-walls impregnated with lignin providing structural support

68
Q

Define transpiration

A

-loss of water vapour from parts of plant exposed to air due to evaporation and diffusion
-consequence of gaseous exchange occurs when plant opens stomata to exchange o2 and co2

69
Q

What is the transpiration stream?

A

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

70
Q

How does water move up the stem?

A

-root pressure
-cohesion tension theory
-capillarity

71
Q

What is root pressure?

A

force that drives water into and up xylem by osmosis due to AT of minerals into xylem by endodermal cells

72
Q

Explain the cohesion tension theory

A

-water molecules form hydrogen bonds with each other causing them to stick together
-surface tension of the water creates sticking effect
-as water is lost through transpiration, more is drawn up the stem from roots

73
Q

Define capillarity

A

tendency of water to move up the xylem against gravity due to adhesive forces that prevent water column dropping back

74
Q

State the factors that affect rate of transpiration

A

-light
-temp
-humidity
-air movement

75
Q

How does temp affect rate of transpiration?

A

higher temp increases random motion and rate of evaporation so ROT increases

76
Q

How does light affect the rate of transpiration?

A

higher light intensity increases rate of photosynthesis causing more stomata to open for gas exchange so ROT increases

77
Q

How does humidity affect rate of transpiration?

A

high humidity = water content of air next to leaf is high which reduces concentration gradient so ROT decreases

78
Q

How does air movement affect rate of transpiration?

A

large amounts of air blow moist air away from leaves creating steep concentration gradient so ROT increases

79
Q

What is a hydrophyte?

A

plants that are adapted to live and reproduce in very wet habitats e.g. water lilies

80
Q

Give adaptations of hydrophytes that allow them to live in wet conditions

A

-thin/absent waxy cuticle
-stomata often open
-wide, flat leaves
-air spaces for buoyancy

81
Q

What is a xerophyte?

A

plants able to live and reproduce in very dry habitats where water availability is low e.g. cacti

82
Q

Give adaptations of xerophytes that allow them to live in dry conditions

A

-small/rolled leaves
-densely packed mesophylls
-thick waxy cuticle
-sstomata often closed
-hair traps moist air

83
Q

What are mesophytes?

A

-terrestrial plants adapted to live in environments with average conditions and an adequate water supply
-have features that enable their survival at unfavourable times of the year

84
Q

Relate the structure of the phloem to its functions

A

-sieve tube elements transport sugars around plant
-companion cells designed for AT of sugars into tubes
-plasmodoesmata allow communication and exchange of substances between sieve tubes and companion cells

85
Q

What are cytoplasmic strands?

A

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

86
Q

Describe the function of cytoplasmic strands

A

-allow communication and exchange of materials between sieve tube elements and companion cells
-holds nucleus in place

87
Q

Define translocation

A

movement of organic compounds in the phloem from sources to sinks

88
Q

Summarise the mass-flow hypothesis of translocation

A

-sugar loaded into sieve tubes via AT
-lowers water potential causing water to move in from the xylem
-hydrostatic pressure causes sugar to move towards the sink

89
Q

What is a potometer?

A

apparatus used to measure water uptake from a cut shoot

90
Q

What is autoradiography?

A

technique used to record the distribution of radioactive material within a specimen

Biology Unit 2 (4 decks)

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