transport Flashcards

1
Q

Name essentials features of a transport system

A

Blood or fluid to carry dissolved substances and cells
System of blood vessels distributing blood around the body
A pump to circulate the blood in the vessels
Valves to prevent back-flow

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2
Q

Name advantages and disadvantages of an open circulatory system and give an example of where it occurs

A

Advantage: No blood pigment required
Disadvantage: Low pressure, blood moves slowly
Found in insects

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3
Q

Name advantages and disadvantages of a closed circulatory system and give an example of where it occurs

A

Advantage: More efficient, high pressure
Disadvantage: Blood vessels and pigment required
Found in Earthworms

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4
Q

Name advantages and disadvantages of a single circulatory system and give an example of where it occurs

A

Advantage: Blood passes through heart once
Disadvantage: Very low pressure, blood returns to heart slowly
Found in fish

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5
Q

Name advantages and disadvantages of a double circulatory system and give an example of where it occurs

A

Advantages: High pressure, more efficient, blood pressure maintained
Disadvantages: Heart requires four chambers
Found in mammals

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6
Q

Features of venules

A

Larger lumens than arterioles and thinner walls

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7
Q

Features of arterioles

A

Thinner than arteries, muscular walls with the ability to vasoconstrict and vasodilate

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8
Q

Features of arteries

A
Thick muscular walls
Oxygenated blood except in pulmonary vein 
Away from the heart 
High blood pressure 
Branch into arterioles
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9
Q

Features of veins

A
Thinner, less muscular walls
Large lumen, irregularly shaped 
Deoxygenated blood except in the pulmonary vein 
Form from venules 
Contain valves 
Low blood pressure
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10
Q

Features of capillaries

A

Thin walls; one cell thick
Pores in walls make them permeable
Small diameter, slow blood down
Allows for diffusion between blood and tissue fluid

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11
Q

Describe the intrinsic contraction of heart muscle

A

Myogenic

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12
Q

What valve is between the left atrium and ventricle

A

Mitral valve is the name of the atrio-ventricular valve on the LEFT side.

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13
Q

What valve is between the right atrium and ventricle

A

Tricuspid valve

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14
Q

Describe the pressure in the heart when the semi-lunar valves are open

A

Blood enters aorta, aorta pressure high

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15
Q

Describe the pressure in the heart when the atrioventricular valves are open

A

Atrial systole, pressure high in atria

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16
Q

Describe the pressure in the heart when the atrioventricular valves are closed

A

Ventricular systole, pressure high in ventricles

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17
Q

What does the P wave on an ECG show

A

Depolarisation through the atria during atrial systole

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18
Q

What does the QRS wave on an ECG show

A

Depolarisation through ventricles just before ventricular systole

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19
Q

What does the PR segment show on an ECG

A

Delay at the AV node

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20
Q

How would you identify atrial fibrillation on an ECG

A

The tracing shows tiny, IRREGULARLY IRREGULAR fibrillations between heartbeats. The rhythm is irregular and erratic, and there may be no P wave

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21
Q

How would you identify a myocardial infarction (heart attack) on an ECG

A

ST Elevation

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22
Q

How would you identify an enlarged left ventricle on an ECG

A

The QRS complex has a greater amplitude and voltage

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23
Q

What is a granulocyte

A

Phagocytic white blood cells

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24
Q

What is an agranulocyte

A

Lymphocytic white blood cells

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25
Q

What is a thrombocyte

A

A platelet

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26
Q

What is an erythrocyte

A

A red blood cell

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27
Q

How is oxygen transported with haemoglobin

A

It associates with haemoglobin in the alveoli and dissociates as the tissues requires oxygen

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28
Q

Describe the path of the electrical impulse in the heart

A

Begins at the SA node before depolarising to both atria causing them to contract. The impulse is halted at the AV node to prevent the ventricles from contracting to soon, before the impulse travels down the Bundle of His to the Purkinje fibres, causing the ventricles to contract from the bottom upwards

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29
Q

Describe the Bohr effect

A

The presence of carbon dioxide in the blood causes the formation of carbonic acid which causes the haemoglobin to reduce its affinity for oxygen and release it into the tissues

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30
Q

What is myoglobin

A

Found in skeletal muscle and has a very high affinity for oxygen, allowing it to store oxygen until the muscle is short of it, eg, in sustained exercise.

31
Q

Describe the structure of myoglobin

A

Has a tertiary structure with only one haem

32
Q

Describe the haemoglobin affinity curve for organisms living in hypoxic conditions

A

The curve is shifted to the left

33
Q

What are the three ways carbon dioxide is carried in the blood

A

Dissolved in blood plasma
Carbamino-haemoglobin
Hydrogen carbonate ions

34
Q

Describe how carbon dioxide becomes hydrogen carbonate ions and the chloride shift.

A

Carbonic anhydrase catalyses the reaction between CO2 and water to form carbonic acid. A hydrogen dissociates, lowering the pH, and forcing the hydrogen carbonate ions out of the cell. This lets chloride ions in to balance the pH.

35
Q

What is the role of haemoglobin during the transport of CO2

A

A pH buffer by combining with hydrogen ions to form haemoglobinic acid

36
Q

Describe the formation of tissue fluid

A

When the hydrostatic pressure as the blood enters the capillary is greater than the osmotic pressure in the tissues, blood plasma is forced out of the pores in the capillaries and into the tissue

37
Q

Describe the reabsorption of tissue fluid

A

At the venous end of the capillary bed, the hydrostatic pressure is less than the osmotic pressure, forcing the tissue fluid back into the blood stream

38
Q

What are lymphatic vessels for

A

Draining away excess tissue fluid

39
Q

What is retention of tissue fluid called

A

Oedema

40
Q

What remains in the capillaries when the fluid is forced out

A

Red blood cells and plasma proteins

41
Q

What is the apoplast pathway

A

Water moves through the gaps between the cellulose microfibres in the cell wall

42
Q

What is the symplast pathway

A

Water moves through the cytoplasm and the plasmodesmata in the cell wall

43
Q

What is the vacuolar pathway

A

Water moves from vacuole to vacuole

44
Q

What is the Casparian strip

A

An impermeable band of suberin across the cell walls of the endodermal cells blocks the apoplast pathway and pushes the water into the symplast

45
Q

What is the vascular system in the root called

A

Vascular stele

46
Q

What is the vascular system in the stem called

A

Vascular bundle

47
Q

What are the three plant macronutrients

A

Nitrogen, phosphorus, potassium

48
Q

How is nitrogen taken into the plant

A

Nitrogen is absorbed as dissolved ammonium or nitrate ions into the apoplastic stream by diffusion. The ions are absorbed into the symplast pathway by active transport

49
Q

How are root hair cells adapted for absorption

A

Thin cell walls
Large SA:V ratio
Large number of mitochondria
Large sap vacuole

50
Q

What are mycorrhizae

A

Fungi that grow around plant roots to increase the surface area for absorption. The plant supplies the fungi with sugars

51
Q

How is water taken up the xylem

A

Root pressure
Cohesion and adhesion in the transpiration stream
Capillarity

52
Q

How does root pressure work

A

Plants take up ions, lowering the water potential and drawing water in causing positive hydrostatic pressure forcing water upwards

53
Q

What are the transport cells in phloem

A

Sieve tube cells

54
Q

What is the sieve plate

A

Contains tiny holes at the end of the sieve tube allowing sugar solution to pass through

55
Q

What is the role of a companion cell

A

Regulate the metabolism of the sieve tube cell and load and unload sugar from the phloem

56
Q

Which part of the phloem and xylem vessels provides strength

A

Sclerenchyma cells and fibres

57
Q

What is the role of tracheids

A

heavily strengthened, conducting cells

58
Q

What is the role of parenchyma cells

A

Storage/packing cells

59
Q

What is the role of vessels in plants

A

Conducting vessels

60
Q

How are vessel elements is plants adapted to their function

A

Large diameter cells offer low water resistance and allows rapid uptake of water

61
Q

Describe the vascular tissue in leaves

A

A system of veins resistant to tearing

62
Q

Describe the effects of the following on transpiration:

Temperature
Air movement
Humidity
Light intensity

A

Temperature: Increased temperature increases the kinetic energy of water molecules and as such increases the rate of transpiration

Air movement: Increased air movement causes recently removed water to move far away from the stomata, increasing the concentration gradient and increasing the rate of transpiration

Humidity: High levels of humidity decrease the concentration gradient between the inside of the leaf and the air around the leaf, decreasing the rate of transpiration

Light intensity: High light intensity causes the stomatal opening to open more, allowing more water out and increasing the rate of transpiration

63
Q

How do you set up a potometer correctly

A

Keep leaves dry
Set up apparatus underwater
Cut shoot underwater
Ensure all joints are airtight

64
Q

Describe translocation

A

Movement of sugars from their source to their sink via the phloem

65
Q

What is a source and what is a sink

A

source: site of the photosynthesis of the sugars
sink: where the products of photosynthesis may be used for growth or storage

66
Q

How are substances transported between the companion cells and the sieve tube cells

A

Plasmodesmata

67
Q

Describe the ringing experiments to prove translocation

A

Bark was removed in a ring around a tree, thus removing the phloem. No sugar was then found below the site of the ring, proving the sugars are transported in the phloem to the whole plant

68
Q

Describe how aphids have been used to prove translocation

A

Aphids have hollow, needle-like mouthparts called a stylet. The stylet is inserted directly into the sieve tube allowing the aphid to feed on the sugary sap. The stylet can be cut off (using a laser) leaving it attached to the plant (it forms a useful micropipette). Sap exuding from the stylet is collected and analysed. Analysis shows that the sap contains the products of photosynthesis – sucrose and amino acids.

69
Q

Describe how radioactive labelling can be used to prove translocation

A

Carbon dioxide labelled with radioactive carbon is supplied to an illuminated plant leaf. The radioactive carbon is fixed in the sucrose produced by photosynthesis and is translocated to other parts of the plant. This radioactive carbon in the sucrose can be traced using autoradiography

70
Q

Describe the mass flow hypothesis

A

 When sugar is made at the source the water potential becomes more negative and water passes into the source cells by osmosis.
 As water enters the source cells, hydrostatic pressure increases forcing sugars and other products of photosynthesis into the sieve tubes – phloem sieve tubes are loaded.
 Mass flow occurs along the sieve tubes to the sink, the products of photosynthesis are forced along by the flow of water from a high to a low hydrostatic pressure.
 Hydrostatic pressure will be lower at the sink because sugars are stored as starch or are used for respiration; this reduces the water potential.
 Water passes from the sink cells to the xylem to be returned to the source.

71
Q

Name arguments against the mass flow hypothesis

A

The rate of translocation is 10,000 times faster than it would be if the substances were moving by diffusion.
Sieve plates with tiny pores act as a barrier impeding flow.
Sucrose and amino acids move at different rates and in different directions in the same phloem tissue.
Phloem tissue has a high rate of oxygen consumption, and translocation is stopped when a respiratory poison such as potassium cyanide enters the phloem.
Companion cells contain numerous mitochondria and produce ATP, but the mass flow hypothesis fails to suggest a role for the companion cells.

72
Q

Describe how the waterlily is adapted to its environment

A

it is a HYDROPHYTE and so is surrounded by water. Therefore, it has a poorly developed xylem structure as it doesn’t need to transport much water. The stomata are on the top of the lilypad because the underside is submerged. It also has little to no waxy cuticle as water loss is not an issue, and large air spaces in the spongy mesophyll for buoyancy

73
Q

Describe how marram grass is adapted to its environment

A

it is a XEROPHYTE and is surrounded by little water. The plant features rolled leaves, sunken stomata, a thick waxy cuticle and hairs to trap water vapour, all the reduce water loss.

74
Q

Describe mesophytes

A

 Mesophytes flourish in habitats with adequate water supply.
 Most plants of temperate regions are mesophytes.
 Most crops are mesophytes.
 Close stomata during the night to decrease water loss.
 Shed leaves in the winter to survive unfavourable times e.g. frost.
 Underground organs survive winter e.g. bulbs.
 Annual mesophytes (plants which flower, produce seed and die in the same year) survive the winter as dormant seeds.