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GCSE Edexcel Biology > Topic 8 - Exchange and Transport in Animals > Flashcards

Topic 8 - Exchange and Transport in Animals Flashcards

1
Q

What waste product would a cell get rid of, whilst taking in substances it needs for life processes from the environment?

A

Cells need oxygen for aerobic respiration, which produces carbon dioxide as a waste product. These two gases move between cells and the environment by diffusion.

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2
Q

What waste product would water get rid of, whilst taking in substances it needs for life processes from the environment?

A

Water is taken up by cells by osmosis. In animals, dissolved food molecules (the products of digestion, e.g. glucose, amino acids) and mineral ions diffuse along with it.

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3
Q

What is urea?

A

A waste product produced by animals from the breakdown of proteins

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4
Q

What is urea removed from and by?

A

It diffuses into the blood plasma for removal from the body by the kidneys

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5
Q

What does a small surface area to volume ratio mean?

A

The organism is larger

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6
Q

What does a big surface area to volume ratio mean?

A

The organism is smaller

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7
Q

How do you calculate the volume?

A

volume = length * width * height

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8
Q

How do you calculate the surface area of an object?

A

Find the area of all the sides, using the equation, area = length * width. Then add all the areas together.

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9
Q

How should a surface area to volume ratio be written?

A

The volume should always be 1.

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10
Q

Why are exchange surfaces needed in single-celled organisms?

A

In single-celled organisms, gases and dissolved substances can diffuse directly into (or out of) the cell across the cell membrane. It’s because they have a large surface area compared to their volume, so enough substances can be exchanged across the membrane to supply the volume of the cell.

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11
Q

Why are exchange surfaces needed in multicellular organisms?

A

Multicellular organisms (such as animals) have a smaller surface area compared to their volume. This makes it difficult to exchange enough substances to supply their entire volume across their outside surface alone. This means they need some sort of exchange surface for efficient diffusion and a transport system to move substances between the exchange surface and the rest of the body.

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12
Q

What factors affect the rate of diffusion?

A
  • Temperature
  • Surface area
  • Concentration difference (gradient)
  • Distance to move
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13
Q

How does temperature affect the rate of diffusion?

A

If the temperature increases, the rate of diffusion increases, but if temperature decreases the rate of diffusion decreases

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14
Q

How does surface area affect the rate of diffusion?

A

The more surface there is available for molecules to move across, the faster they can get from one side to the other.

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15
Q

How does the concentration difference (gradient) affect the rate of diffusion?

A

Substances diffuse faster if there is a big difference in concentration between the area they are diffusing from and the area they are diffusing to. If there are lots more particles on one side, there are more there to move across.

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16
Q

How does the distance to move affect the rate of diffusion?

A

Substances diffuse more quickly when they haven’t as far to move. The thinner the exchange surface (e.g. a cell membrane) the shorter the distance substances have to diffuse across it and so the faster the rate of diffusion. The posh way of saying this is that the substances have a ‘short diffusion pathway’.

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17
Q

What is Fick’s law?

A

rate of diffusion ∝ (surface area * concentration difference) ÷ thickness of membrane

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18
Q

What does Fick’s law mean?

A

The rate of diffusion increases in proportion to (at the same rate as) the surface area or concentration difference and inverse proportion to the thickness of the membrane

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19
Q

How can the rate of diffusion double (using Fick’s law)?

A
  • if the surface area or concentration doubles
    or
  • if the thickness of the membrane halves
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20
Q

What is the rate of diffusion measured in?

A

a.u.

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21
Q

What does a.u. stand for?

A

arbitrary units

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22
Q

In humans (and other mammals), where are gases exchanged by diffusion?

A

alveoli

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23
Q

What is the function of the lungs?

A

To transfer oxygen to the blood and remove waste carbon dioxide from it.

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24
Q

Label a gas exchange in the alveolus diagram

A

https://www.purposegames.com/game/the-alveoli-and-gas-exchange

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25
Q

Label a lungs diagram

A

https://www.purposegames.com/game/respiratory-system-labeling-interactive-game

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26
Q

What are the alveoli surrounded by?

A

blood vessels known as capillaries

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27
Q

Where has the blood arriving to the alveoli come from?

A

It has come from the rest of the body, so it contains lots of carbon dioxide and not much oxygen. This maximises the concentration gradient for the diffusion of both gases.

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28
Q

How is the concentration gradient maximised for oxygen and carbon dioxide, once the blood has come from the body?

A
  • There is a higher concentration of oxygen in the air than in the blood, so oxygen diffuses out of the air in the alveoli and into the blood in the capillaries.
  • Carbon dioxide diffuses in the opposite direction, from a high concentration in the blood to a low concentration in the alveoli, to be breathed out.
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29
Q

What are the adaptations of the alveoli?

A
  • Large surface area to enable more diffusion of oxygen to the blood and more carbon dioxide out of the blood
  • One cell thick so the diffusion distance is small
  • Lots of blood capillaries to ensure a good blood supply to maintain concentration gradients of oxygen and carbon dioxide
  • Moist surfaces for gases to dissolve in, to form a solution to pass through the cell membrane
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30
Q

What does the circulatory system include?

A
  • Blood
  • Blood vessels
  • Heart
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31
Q

What is the function of the circulatory system?

A
  • To get food and oxygen to every cell in the body
  • Carries waste products like carbon dioxide and urea, to where they can be removed from the body
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32
Q

What is a tissue?

A

A group of similar cells that work together to perform a specific function

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33
Q

What is blood?

A

a tissue

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34
Q

What is the function of blood?

A

To transport substances around the body

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35
Q

What is blood made up of?

A
  • Red blood cells
  • White blood cells
  • Platelets
  • All the above are suspended with plasma
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36
Q

What is another name for red blood cells?

A

Erythrocytes

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37
Q

What is the function of a red blood cell?

A

To transport oxygen around the body

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38
Q

Why do red blood cells have a biconcave shape?

A

To give them a large surface area for absorbing oxygen

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39
Q

What is the red pigment found in red blood cells?

A

Haemoglobin, which contains iron. It carries the oxygen

40
Q

Do red blood cells have a nucleus?

A

No. This allows more room for haemoglobin, which means they can carry more oxygen.

41
Q

What happens whilst red blood cells transport the oxygen from the lungs to all cells in the body?

A

In the lungs, oxygen diffuses into the blood. The oxygen combines with haemoglobin in red blood cells to become oxyhaemoglobin.
In body tissues, the reverse happens; oxyhaemoglobin splits up haemoglobin and oxygen, to release oxygen to the cells.

42
Q

Do white blood cells have a nucleus?

A

Yes. This helps to defend against microorganisms that cause disease

43
Q

What are the two types of white blood cells?

A
  • Phagocytes
  • Lymphocytes
44
Q

What is a phagocyte?

A

Phagocytes are white blood cells that change shape to engulf unwelcome microorganisms - this is
called phagocytosis.

45
Q

What is a lymphocyte?

A

Lymphocytes are a group of white blood cells that have different functions depending on their type. For example, B lymphocytes produce antibodies against microorganisms. Some also produce antitoxins to neutralise any toxins produced by the microorganisms.

46
Q

What is a platelet?

A

Small fragments of cells

47
Q

Do platelets have a nucleus?

A

No

48
Q

What is the function of a platelet?

A
  • They help the blood clot (clump together). This seals the wound and stops lots of blood being lost.
  • Stops microorganisms from getting into the wound
49
Q

What happens if there is a lack of platelets?

A

Causes excessive bleeding and bruising

50
Q

What is plasma?

A

A pale straw-coloured liquid which carries just about everything in blood

51
Q

What does plasma carry?

A
  • Red and white blood cells and platelets.
  • Nutrients like glucose and amino acids. These are the soluble products
    of digestion, which are absorbed from the small intestine and taken to the cells of the body.
  • Carbon dioxide from the organs to the lungs.
  • Urea from the liver to the kidneys.
  • Hormones.
  • Proteins.
  • Antibodies and antitoxins produced by the white blood cells.
52
Q

What is an artery?

A

a blood vessel

53
Q

What is the function of an artery?

A

To carry blood away from the heart, towards the organs. The heart pumps the blood out at high pressure, so the artery walls are strong and elastic.

54
Q

What are the characteristics of an artery?

A
  • Contain thick layers of muscle to make them strong
  • Elastic fibres to allow them to stretch and spring back
  • Thick walls
  • Small lumen
55
Q

What is a capillary?

A

a blood vessel

56
Q

What is the function of a capillary?

A
  • Involved in the exchange of materials at the tissues they carry the blood really close to every cell in the body to exchange substances with them
  • They supply food and oxygen to the cells
  • Take away waste products like carbon dioxide
57
Q

What are the characteristics of a capillary?

A
  • Really tiny
  • Permeable walls, so substances being exchanged with the cells can diffuse in and out
  • Walls are one cell thick. This increases the rate of diffusion, by decreasing the distance over which it occurs
  • Very narrow, so they can squeeze into gaps between cells. This gives them a large surface area to volume, which increases the rate of diffusion
  • Contain a nucleus
58
Q

What is a vein?

A

a blood vessel

59
Q

What is the function of a vein?

A

Carry blood to the heart

60
Q

What are the characteristics of a vein?

A
  • Large lumen, to help the blood flow despite the low pressure
  • Thin artery walls, as the blood is at lower pressure in the veins
  • Valves to keep the blood flowing in the right direction to prevent backflow
61
Q

What circulatory system to mammals (including humans) have?

A

A double circulatory system. This means the heart pumps around the body in two circuits.

62
Q

What happens in the first circuits of the double circulatory system?

A

In the first circuit, the heart pumps deoxygenated blood (blood low in oxygen) to the lungs, to take in oxygen. The oxygenated blood then returns to the heart.

63
Q

What happens in the second circuits of the double circulatory system?

A

In the second circuit, the heart pumps oxygenated blood around all the other organs of the body. The blood gives up its oxygen at the body cell and the deoxygenated blood returns to the heart to be pumped out to lungs again.

64
Q

What is a circulatory system, and name a species that has one?

A

Fish have a single circulatory system. Deoxygenated blood from the fish’s body travels to the heart, which then pumps it right round the body again in a single circuit. The blood goes via the gills where it picks up oxygen. In single circulatory systems, only deoxygenated blood goes through the heart.
The blood pressure in single circulatory systems is limited to prevent damage to the capillaries in the gills. In a double circulatory system, blood can be pumped at a low safe pressure in the circuit to the lungs, and at a higher pressure in the circuit to the rest of the body (so material in the blood can reach the cells faster).

65
Q

What is the blood pressure like in a single and double circulatory system?

A

The blood pressure in single circulatory systems is limited to prevent damage to the capillaries in the gills. In a double circulatory system, blood can be pumped at a low safe pressure in the circuit to the lungs, and at a higher pressure in the circuit to the rest of the body (so material in the blood can reach the cells faster).

66
Q

What is the structure of the mammalian heart?

A

The mammalian heart has four chambers (the right atrium, right ventricle, left atrium and left ventricle) which it uses to pump blood around. The major blood vessels leading into and out of these chambers are the vena cava, pulmonary artery, aorta and pulmonary vein. The walls of the heart are mostly made of muscle tissue, which contracts to pump the blood.

67
Q

Where does the right side of the mammalian heart lead to?

A

to the lungs

68
Q

Where does the left side of the mammalian heart lead to?

A

to the body

69
Q

Why does the heart have valves?

A

To make sure the blood goes in the same direction - to prevent backflow

70
Q

Which side of the heart does deoxygenated blood flow on?

A

Left

71
Q

Which side of the heart does oxygenated blood flow on?

A

Right

72
Q

How does blood flow through the heart?

A

1) The right atrium of the heart receives deoxygenated blood from the body through the vena cava. The left atrium receives oxygenated blood from the lungs through the pulmonary vein.
2) The atria contract, pushing the blood into the ventricles.
3) The ventricles contract. Deoxygenated blood moves from the right ventricle to the lungs via the pulmonary artery. The oxygenated blood moves from the left ventricle to the whole body via the aorta

73
Q

What are the thickness of the chamber walls in the heart related to?

A

Their function

74
Q

How thick are the atria walls in the heart?

A

Both atria walls are relatively thin. They only need to pump blood a short distance to the ventricles, so they don’t require much muscle.

75
Q

How thick are the ventricle walls in the heart?

A

The ventricles have to pump blood further, so their chamber walls are thicker than those of the atria. The wall of the left ventricle is much thicker than the wall of the right ventricle. This is because the left ventricle needs more muscle to pump blood around the whole body at high pressure, whereas the right ventricle only has to pump blood to the lungs.

76
Q

What is cardiac output?

A

The total volume of blood pumped by a ventricle every minute

77
Q

How do you calculate the cardiac output?

A

cardiac output = heart rate * stroke volume

78
Q

What is the cardiac output measured in?

A

cm^3 min^-1

79
Q

What is the heart rate measured in?

A

bpm (beats per minute)

80
Q

What is the stroke volume measured in?

A

cm^3

81
Q

What is the beats per minute referring to?

A

The heart rate

82
Q

What is the stroke volume referring to?

A

The volume of blood pumped by one ventricle each time it contracts

83
Q

What is respiration known as?

A

Cellular respiration?

84
Q

What is cellular respiration?

A

Cellular respiration is the process of transferring (releasing) energy from the breakdown of organic compounds (usually glucose). This energy is used to fuel metabolic processes - the necessary chemical reactions that take place inside living organisms. Because energy is transferred to the environment, respiration is an exothermic reaction. Some of this energy is transferred by heat.

85
Q

What are the two types of respiration?

A
  • Aerobic
  • Anaerobic
86
Q

What is the energy transferred from respiration used for?

A

Metabolic processes, such as:
- Organisms use energy for reactions that involve building up larger molecules from smaller ones (like proteins from amino acids).
- Animals use energy in the chemical reactions that allow their muscles to contract (which in turn allows them to move about).
- Mammals and birds use energy to keep their body temperature steady (unlike other animals, mammals and birds keep their bodies constantly warm).

87
Q

What is aerobic respiration?

A

Respiration using oxygen. Most of the reactions for aerobic respiration happen inside the cell structure called mitochondria.

88
Q

What is the word equation for aerobic respiration?

A

glucose + oxygen ——> carbon dioxide + water

89
Q

What is the symbol equation for aerobic respiration?

A

C6H12O6 + 6O2 —–> 6CO2 + 6H2O

90
Q

How much energy is transferred in aerobic respiration?

A

a large amount

91
Q

What is anaerobic respiration in animals?

A

When exercising, your breathing rate and heart rate increase, so not enough oxygen is left in the body, so your muscles start anaerobically respiring as well.
Glucose is only partially broken down, so not that much energy is transferred.

92
Q

What is the word equation for anaerobic respiration in animals?

A

glucose ——-> lactic acid

93
Q

What is the symbol equation for anaerobic respiration in animals?

A

C6H12O6 —–> 2C3H6O3

94
Q

What is anaerobic respiration in plants?

A

Plants respire without oxygen

95
Q

What is the word equation for anaerobic respiration in plants?

A

glucose ——> ethanol + carbon dioxide

96
Q

What is the symbol equation for anaerobic respiration in plants?

A

C6H12O6 ——> 2C2H5OH + 2CO2

97
Q

How much energy is transferred in anaerobic respiration?

A

a small amount

GCSE Edexcel Biology (20 decks)

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