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A-level Biology > Chapter 7 > Flashcards

Chapter 7 Flashcards

1
Q

What are the thick muscular walls of the heart called

A

Cardiac muscle

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2
Q

What are the uniques properties of the cardiac muscle

A

• It is myogenic, meaning it can contract and relax without nervous or hormonal stimulation

• It never fatigues, as long as it have a supply of oxygen

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3
Q

What do the coronary arteries do

A

Supply cardiac muscle with oxygenated blood

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4
Q

Where are the coronary arteries

A

They branch of from the aorta

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5
Q

What happens if the coronary arteries become blocked

A

If they become blocked cardiac muscle won’t receive oxygen, therefore will not be able to respire and the cells will die.

This results in myocardial infarction (a heart attack)

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6
Q

What are the 4 chambers of the Heart

A

Left atrium

Right atrium

Left ventricle

Right ventricle

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7
Q

What are the atria

A

Thinner muscular walls.

Do not need to contact as hard as not pumping blood far (only to ventricles)

Elastic walls to stretch when blood enters

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8
Q

What are the ventricles

A

Thicker muscular walls to enable Right pulmonary arteries, bigger contraction.

This creates a higher blood pressure to enable blood to flow longer distances (to the lungs and the rest of the body)

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9
Q

What does the right ventricle do and how is it adapted for its function

A

Pumps blood to the lungs.

This needs to be at a lower pressure to prevent damage to capillaries in the lungs and so blood flows slowly to allow time for gas exchange

Therefore, thinner muscular wall in comparison to the left ventricle

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10
Q

What does the left ventricle do and how is it adapted for its function

A

Pumps blood to the body. This needs to be at a higher pressure to ensure blood reaches all the cells in the body.

Therefore, much thicker muscular wall in comparison to the right ventricle to enable larger contractions of the muscle to create higher pressure.

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11
Q

What does pulmonary refer to

A

The lungs

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12
Q

What does the vena cave do

A

(Means body vein) Carries deoxygenated blood from the body into the right atrium

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13
Q

What does the pulmonary vein do

A

Carries oxygenated blood from the lungs to the left atrium

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14
Q

Do veins carry blood away or towards the heart

A

Veins IN to the heart

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15
Q

Do arteries carry blood towards our away from the heart

A

A away from the heart

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16
Q

What does the pulmonary artery do

A

Carries deoxygenated blood from the right ventricle to the lungs to become oxygenated

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17
Q

What does the aorta do

A

Carries oxygenated blood from the left ventricle to the rest of the body

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18
Q

Where are the semi lunar valves

A

In aorta and pulmonary artery

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19
Q

Where are the atrioventricluar valves

A

Between atria and ventricles

Bicuspid (left side)

Tricuspid (right side)

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20
Q

What do valves do

A

Prevent backflow of blood

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21
Q

What doe the valves do when pressure is higher/lower

A

Open when pressure is higher behind the valve.

Close when pressure is higher in front of the valve

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22
Q

What is the septum and what does it do

A

Separates the deoxygenated and oxygenated blood

Maintains high concentration of oxygen in oxygenated blood to maintain concentration gradient to enable diffusion at respiring cells.

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23
Q

How many stages is the cardiac cycle

A

3

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24
Q

What are the 3 stages of the cardiac cycle

A

Diastole

Atrial systole

Ventricular Systole

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25
Q

What happens in Diastole

A

The atria and ventricular muscles are relaxed

This is when blood will enter the atria via the vena cava and pulmonary vein.

The blood flowing into the atria increases the pressure within the atria

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26
Q

What happens in atrial systole

A

The atria muscular walls contract, increasing the pressure further.

This causes the atrioventricular valves to open and blood to flow into the ventricles.

The ventricular muscular walls are relaxed
(ventricular diastole)

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27
Q

What happens in ventricular systole

A

After a short delay, the ventricle muscular walls contract, increasing the pressure beyond that of the atria.

This causes the atrioventricular valves to close and the semi-lunar valves to open.

The blood is pushed out of the ventricles into the arteries (pulmonary and aorta)

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28
Q

What is the cardiac output

A

The volume of the blood which leaves one ventricle in one minute is the cardiac output.

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29
Q

What is the equation for cardiac output

A

Cardiac output = heart rate X stroke volume

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30
Q

What is heart rate

A

Beats of the Heart per minute min-1

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31
Q

What is the stroke volume

A

Volume of blood that leaves the heart each beat dm3

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32
Q

When do atrioventricular valves open

A

Atriventricular valves open when the pressure is higher in the atria compared to the ventricles.

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33
Q

When do atrioventricular valves close

A

They close when the pressure is higher in the ventricles compared to the atria

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34
Q

When do semi-lunar valves open

A

Semi-lunar valves open when the pressure is higher in the ventricle compared to the arteries (pulmonary artery or aorta).

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35
Q

When do semi-lunar valves close

A

They close when the pressure is higher in the arteries compared to the ventricles

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36
Q

How do the valves ensure blood flow is unidirectional

A

The pressure and volume changes within each chamber of the heart cause the valves to open and close which ensures blood flow is unidirectional.

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37
Q

Why is it useful to represent pressure and volume changes within the heart on a graph

A

These pressure and volume changes can been represented on graphs to make it possible to identify when the valves open/close during the cardiac cycle

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38
Q

Describe the mechanism by which an arteriole regulates blood flow to capillaries. (2 marks)

A

The smooth muscle within the arteriole contracts.

This contraction leads to the narrowing or constriction of the arteriole lumen.

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39
Q

Which blood vessel transports blood at the lowest pressure: capillary, pulmonary vein, renal vein, vena cava

A

Vena cava

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40
Q

Describe the function of the coronary arteries.
(2 mark)

A

(Carry) oxygen / glucose

(To) heart muscle

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41
Q

Name the blood vessel that carries deoxygenated blood from the body into the heart. (1 mark)

A

Vena cava

42
Q

Name the blood vessel that carries blood from the heart to the kidneys. (1 mark)

A

Renal artery

43
Q

Suggest why there are larger fluctuations in blood pressure in the aorta than in the small arteries.(3 marks)

A
  1. Aorta is close to the heart
  2. (Aorta has) elastic tissue;
  3. (Aorta has) stretch/recoil.
44
Q

Explain how the heart contributes to the formation of tissue fluid. (2 marks)

A
  1. Contraction of ventricle(s) produces high blood / hydrostatic pressure;
  2. (This) forces water (and some dissolved substances) out (of blood capillaries);
45
Q

Suggest how might a lymphatic system obstruction lead to the development of lymphoedema, a condition characterised by swelling in the legs. (1 mark)

A

Excess tissue fluid cannot be (re)absorbed / builds up

46
Q

Explain why individuals with significantly elevated ventricular blood pressure experience the build up of tissue fluid outside their blood capillaries? (2 marks)

A
  1. More fluid forced/filtered out of capillary/blood (due to high pressure);
  2. Less return of fluid (into capillary/blood) due to pressure
    OR
    Lymph(atic) (system) cannot drain away all excess fluid;
47
Q

Suggest how does the dilation of blood vessels, induced by certain medications aimed at lowering high ventricular blood pressure, lead to a reduction in ventricular blood pressure? (2 mark)

A
  1. Larger lumen/volume (of blood vessels);.
  2. Reduces (blood) pressure (in blood vessels);
  3. Less friction/resistance (in blood vessels)
48
Q

In an individual with normal cardiovascular function, blood flows unidirectionally through the heart. Give two ways by which this directional flow is maintained.(2 marks)

A
  1. Pressure gradient / moves from high to low pressure;
  2. Valves stop backflow;
49
Q

The aorta has structural features adapted to is function. State four of the structural features and explain how they relate to its function. (4 marks)

A
  1. Elastic tissue to allow stretching smoothes outflow of blood;
  2. (Elastic tissue) stretches when ventricles contract
  3. Muscle for contraction;
  4. Thick wall withstands pressure;
  5. Smooth endothelium reduces friction;
  6. Semi-lunar valve prevents backflow.
50
Q

What’s is the circulatory system in mammals

A

Closed, double circulatory system

51
Q

Why’s the circulatory system in mammals closed

A

the blood remains within the blood vessels.

52
Q

Why’s the circulatory system in mammals double

A

the blood passes through the heart twice in each circuit.

There is one circuit which delivers blood to the lungs and another circuit which delivers blood to the rest of the body.

53
Q

Why do mammals require a double circulatory system

A

To manage the pressure of blood flow

54
Q

Why does the blood flow through the lungs at a lower pressure

A

The blood flows through the lungs at a lower pressure. This prevents damage to the capillaries in the alveoli and also reduces the speed at which the blood flows, enabling more time for gas exchange.

55
Q

What happens to the oxygenated blood from the lungs in the double circulatory system

A

The oxygenated blood from the lungs then goes back through the heart to be pumped out at a higher pressure to the rest of the body. This is important to ensure that the blood reaches all the respiring cells in the body.

56
Q

What are the major blood vessels in the circulatory system

A

The coronary arteries and the following blood vessels attached to these organs:

•Heart (vena cava, aorta, pulmonary artery and pulmonary vein)
• Lungs (pulmonary artery and pulmonary vein)
•Kidneys (Renal artery and renal vein)

57
Q

How are the major blood vessels connected within the circulatory system

A

These major blood vessels are connected within the circulatory system via the arteries, arterioles, capillaries and veins.

58
Q

What do arteries do

A

Arteries carry blood Away (hint to remember -A Away) from the heart and into arterioles.

59
Q

How are the blood vessels linked in the circulatory system

A

Arteries carry blood Away (hint to remember
-A Away) from the heart and into arterioles.

The arterioles are smaller than arteries and connect to the capillaries.

The capillaries connect the arterioles to the veins.

The veins carry blood back into the heart (hint to remember- velNs carry blood IN).

60
Q

Properties of arteries

A

Muscle layer = Thicker than veins so that constriction and dilation can occur to control volume of blood.

Elastic layer = Thicker than veins to help maintain blood pressure. The walls can stretch and recoil in response to the heart beat.

Wall thickness = Thicker wall than veins to help prevent the vessels bursting due to the high pressure.

Valves =no

61
Q

Properties of arterioles

A

Muscle layer = Thicker than in arteries to help restrict blood flow into the capillaries.

Elastic layer = Thinner than in arteries as the pressure is lower

Wall thickness = Thinner as pressure is slightly lower.

Valves = no

62
Q

Properties of veins

A

Muscle layer = Relatively thin so it cannot control the blood flow.

Elastic layer = Relatively thin as the pressure is much lower.

Wall thickness = Thin as the pressure is much lower so there is low risk of bursting. The thinness means the vessels are easily flattened, which helps the flow of blood up to the heart.

Valves = yes

63
Q

Properties of capillaries

A

Muscle layer = no muscle layer

Elastic layer = no elastic layer

Wall thickness = One cell thick consisting of only a lining layer. This provides a short diffusion distance for exchanging materials between the blood an cells.

Valves = no

64
Q

Tracers - investigating translocation

A

involves radioactively labelling C

Plants provided with only radioactively labelled carbon dioxide, over time this’s absorbed into plant and used in photosynthesis to create sugars which all contain radioactively labelled carbon.

Thin slices from stems then cut and placed on x-ray film that turns black when exposed to radioactive material.

When stems are placed on x-ray film section of stem containing the sugars turn black, and this highlights where phloem are and shows sugars are transported in phloem.

65
Q

Ringing experiment - investigating translocation

A

A ring of bark and phloem are peeled and removed off a tree trunk. The result of removing the phloem is that the trunk swells above the removed section.

Analysis of the liquid in this swelling shows it contain sugar.

This shows that when the phloem is removed, the sugars cannot be transported and therefore proves the phloem transports sugars.

66
Q

Translocation (1) - How sucrose transports from the source to the sieve tube element

A

Photosynthesis occurring in the chloroplasts of leaves creates organic substances, e.g. sucrose.

• This creates a high concentration of sucrose at the site of production, therefore sucrose diffuses down its concentration gradient into the companion cell via facilitated diffusion.

• Active transport of H+ occurs from the companion cell into the spaces within the cell walls using energy.

• This creates a concentration gradient and therefore the H+ move down their concentration gradient via carrier proteins into the sieve tube elements.

• Co-transport of sucrose with the H+ ions occurs via protein co-transporters to transport the sucrose into sieve tube element.

67
Q

Translocation (2) - Movement of sucrose within the phloem sieve tube element

A

The increase of sucrose in the sieve tube element lowers the water potential.

• Water enters the sieve tube elements from the surrounding xylem vessels via osmosis.

• The increase is water volume in the sieve tube element increase the hydrostatic pressure causing the liquid to be forced towards the sink.

68
Q

Translocation (3) - Transport of sucrose to the sink (respiring cells)

A

• Sucrose is used in respiration at the sink, or stored or stored as insoluble starch.

• More sucrose is actively transported into the sink cell, which causes the water potential to decrease.

• This results in osmosis of water from the sieve tube element into the sink cell (some water also returns to the xylem).

• The removal of water decreases theolume in the sieve tube element and therefore the hydrostatic pressure decreases.

• Movement of soluble organic substances is due to the difference in hydrostatic pressure between the source and sink end of the sieve tube element.

69
Q

What’s the Mass transport of organic substances in plants is known as

A

Translocation

70
Q

Whats the Mass transport of organic substances (sucrose) in plants from source to sink is due to

A

a hydrostatic pressure gradient in the sieve tube element.

71
Q

How is the hydrostatic pressure created

A

is created by the active transport of sucrose into the sieve tube element, creating lowering the water potential so water moves in by osmosis.

72
Q

What experiments can be used to investigate the transport or organic substances in plants.

A

Tracers and ringing experiments

73
Q

What gas diffuses out of the stomata

A

Oxygen

74
Q

What gas diffuses in through the stomata

A

Carbon dioxide

75
Q

What do stomata do to reduce water loss by evaporation

A

To reduce water loss by evaporation, stomata close at night when photosynthesis wouldn’t be occurring.

76
Q

What are xerophytic plants

A

Xerophytic plants are adapted to survive in environments with limited water.

They have structural features to enable efficient gas exchange to occur whilst also limiting the water loss.

77
Q

Xerophyte adaptations

A

Curled leaves to trap moisture to increase local humidity

Hairs to trap moisture to increase local humidity

Sunken stomata to trap moisture to increase

Thicker cuticle to reduce evaporation

Longer root network to reach more water.

78
Q

What’s transpiration

A

The loss of water vapour from the stomata by evaporation.

79
Q

What are 4 factors that affect transpiration

A

Light intensity
(Positive correlation - More light causes more stomata to open = larger surface area for evaporation)

Temperature
(Positive correlation - More heat means more kinetic energy, faster moving molecules and therefore more evaporation)

Humidity
(Negative correlation - More water vapour in the air will make the water potential more positive outside of the leaf, therefore reduces the water potential gradient.)

Wind
(Positive correlation - More wind will blow away humid air containing water vapour, therefore maintaining the water potential gradient.)

80
Q

Movement of water up the xylem

A

Water moves up a plant from the roots against gravity. This could be several metres against gravity in large trees!

81
Q

How is the MOVEMENT OF WATER UP THE XYLEM possible

A

Cohesion-tension theory
+ Cohesion
+ Capillarity — adhesion
+ Root Pressure

82
Q

Why is cohesion possible in water

A

Water is a dipolar molecule (slight negative oxygen and slight positive hydrogens.

This enables hydrogen bonds to form between the hydrogen and oxygen of different water molecules.

This creates cohesion between water molecules - they stick together. Therefore water travels up the xylem as a continuous water column.

HB hold together water molecules (cohesion)

83
Q

Capillarity

A

Adhesion of water is when water sticks to other molecules. Water adheres to the xylem walls.

The narrower the xylem the bigger the impact of capillarity.

84
Q

Root pressure

A

As water moves into the roots by osmosis it increases the volume of liquid inside the root and therefore the pressure inside the root increases.

This is known as root pressure.

This increase in pressure in the roots forces water above it upwards (positive pressure).

85
Q

Process of movement of water up the xylem

A

I. Water vapour evaporates out of stomata on leaves. This loss in water volume creates a lower pressure.

  1. When this water is lost by transpiration more water is pulled up the xylem to replace it (moves due to negative pressure).
  2. Due to the hydrogen bonds between water molecules, they are cohesive (stuck together). This creates a column of water within the xylem.
  3. Water molecules also adhere (stick) to the walls of the xylem. This helps to pull the water column upwards.
  4. As this column of water is pulled up the xylem it creates tension, pulling the xylem in to become narrower.
86
Q

What are the 2 key cells that the phloem tissue contains

A

I. sieve tube elements
2. companion cells

87
Q

What are sieve tube elements

A

Living cells
Contain no nucleus
Contain fencorganelles

88
Q

What is a Companion cells

A

Provide ATP required for active transport of organic substances

89
Q

What is the transport of organic substances in a plant

A

Requires energy - active (co-transport)

90
Q

Source to sink explanation

A

Sucrose lowers water potential of source cell.
Water enters by osmosis - This increases the hydrostatic pressure in the source cell

Respiring cell is using up sucrose, and therefore it has a more positive water potential. Water leaves the sink cell by osmosis - This decreases the hydrostatic pressure in the sink cell

The source cell has a higher hydrostatic pressure than the sink cell, so the solution is forced towards the sink cell via the phloem.

91
Q

What is haemoglobin

A

Haemoglobins are groups of proteins found in different organisms.

protein with quaternary structure.

Haemoglobin and red blood cells transport of oxygen

92
Q

What is Affinity of haemoglobin for oxygen

A

The ability of haemoglobin to attract, or bind, oxygen

93
Q

What is the Saturation of haemoglobin with oxygen

A

When haemoglobin is holding the maximum amount of oxygen it can bind

94
Q

What is the Loading / association of haemoglobin

A

binding of oxygen to haemoglobin

95
Q

What is the Unloading dissociation of haemoglobin

A

When oxygen detaches, or unbinds, from haemoglobin

96
Q

OXYHAEMOGLOBIN DISSOCIATION CURVE

A

Oxygen is loaded in regions with a high partial pressure of oxygen (e.g. alveoli) and is unloaded in regions of low partial pressure of oxygen (e.g. respiring tissues). This is shown on the oxyhaemoglobin dissociation curve.

97
Q

COOPERATIVE BINDING

A

The cooperative nature of oxygen binding to haemoglobin is due to the haemoglobin changing shape when the first oxygens binds. This then makes it easier further oxygens to bind.

98
Q

What is the Bohr effect?

A

The Bohr effect is when a high carbon dioxide concentration causes the oxyhemoglobin curve to shift to the right. The affinity for oxygen decreases because the acidic carbon dioxide changes the shape of haemoglobin slightly.

99
Q

Why do animals have different types of haemoglobin

A

Animals have different types of haemoglobin which have different affinities for oxygen, which is an adaptation to their environments.

100
Q

What are some examples of organisms with different types of haemoglobin

A

Llama - Llamas live at high altitudes where there is a lower partial pressure of oxygen.

Dove - Faster metabolism, so needs more oxygen for respiration to provide energy for contracting muscles

Earthworm - Underground there is lower a partial pressure of oxygen

A-level Biology (15 decks)

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