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GCSE Edexcel Biology grade 9-1 course, topics 6-9 > Topic 8 > Flashcards

Topic 8 Flashcards

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1
Q

what must all organisms do?

A

take in substances that they need from the environment and get remove any waste products

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2
Q

why do cells need oxygen?

A

for aerobic respiration which produces carbon dioxide as a waste product

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3
Q

how do oxygen and carbon dioxide move between cells and the environment?

A

by diffusion

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4
Q

how is water taken up by cells?

A

by osmosis

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5
Q

what substances diffuse with water in animals?

A

food molecules (the products of digestion) and mineral ions

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6
Q

what are some examples of food molecules which diffuse with water in animal cells?

A

glucose and amino acids

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7
Q

what are three substances which organisms exchange with the environment?

A

oxygen, water and urea

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8
Q

where does urea diffuse from cells to? and why?

A

urea diffuses from cells to the blood plasma for removal from the body by the kidneys

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9
Q

what does an organism’s ease to exchange substances with its environment depend on?

A

the organism’s surface area to volume ratio (SA:V)

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10
Q

what does a ratio show?

A

how large one value is compared to another

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11
Q

how does an organism’s SA:V vary with the size of the organism?

A

the larger an organism is, the smaller its surface area is compared to its volume

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12
Q

what is the equation for the area of a surface?

A

length x width

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13
Q

what is the equation for a volume of a block?

A

length x width x height

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14
Q

in single-celled/ unicellular organisms, how do substances diffuse into/ out of the cell?

A

the gases and dissolved substances can diffuse directly into/ out of the cell across the cell membrane because the cells 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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15
Q

how do multicellular organisms diffuse/ exchange substances to supply to the volume of the organism?

A

multicellular organisms need exchange surfaces for efficient diffusion and a mass transport system to move substances between the exchange surface and the rest of the body. this is because multicellular organisms have a smaller surface area compared do to their volume which makes it difficult to exchange substances to supply to their entire volume across their outside surface alone.

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16
Q

what are alveoli?

A

an exchange surface found in the lungs of mammals which are well-adapted for the efficient exchange of oxygen and carbon dioxide. they are in the form of small “air sacs”

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17
Q

how are gases exchanged in the lungs?

A

by diffusion

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18
Q

what three factors affect the rate of diffusion of any substance?

A
  • distance
  • concentration difference / concentration gradient
  • surface area
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19
Q

how can distance affect the rate of diffusion?

A

substances diffuse faster when the substances don’t have to move as far

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20
Q

how can concentration gradient affect the rate of diffusion?

A

substances diffuse faster if there’s a large difference in concentration between the area the substances are diffusing from and the area the substances are diffusing to. this is because there is a greater concentration of particles to move from one side of the membrane to the other.

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21
Q

how can surface area affect the rate of diffusion?

A

the greater the surface area, the more surface there is available for the molecules to move across so the faster the molecules can travel from one side to the other.

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22
Q

what is the function of the lungs?

A

to transfer oxygen to the blood and to remove waste carbon dioxide from the blood

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23
Q

where does gas exchange happen in mammals?

A

in the lungs, in the alveoli

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24
Q

what is the singular form of “alveoli”?

A

alveolus

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25
Q

describe the process of gas exchange in the alveoli

A
  • blood returning from the rest of the body and arriving at the lungs contains lots of carbon dioxide and a small amount of oxygen. this maximises the concentration gradient for the diffusion of the gases
  • oxygen diffuses out of the air in the alveoli where the concentration of oxygen is is high and into the blood where the concentration of oxygen is low. carbon dioxide diffuses in the opposite direction to be breathed ou
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26
Q

how are the alveoli specialised to maximise the diffusion of oxygen and carbon dioxide?

A
  • have a moist lining for dissolving gases
  • have a good blood supply to maintain the concentration gradient of oxygen and carbon dioxide
  • have very thin walls which minimises he distance that the gases have to move
  • the alveoli have a huge surface area
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27
Q

what is the surface area of alveoli in humans?

A

75 m²

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28
Q

which cell membranes do oxygen and carbon dioxide diffuse across in the lungs?

A

the membranes of the cells which make up the walls of the capillary and alveolus.

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29
Q

what is Fick’s Law?

A

the rate of diffusion ∝ (is proportional to)

surface area x concentration difference
—————————————————
thickness of membrane

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30
Q

what does Fick’s Law describe?

A

the relationship between the rate of diffusion and the factors that affect the rate of diffusion

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31
Q

what would happen to the rate of diffusion if the surface area doubled?

A

the rate of diffusion would double

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32
Q

what would happen to the rate of diffusion if the difference in concentration doubled?

A

the rate of diffusion would double

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33
Q

what would happen to the rate of diffusion if the thickness of the membrane halved?

A

the rate of diffusion would double

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34
Q

what is blood?

A

a tissue

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35
Q

what one of the functions of the blood?

A

to act as a huge transport system in the body

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36
Q

what are the four main substances / cells in the blood?

A
  • red blood cells
  • white blood cells
  • plasma
  • platelets
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37
Q

what are red blood cells also known as?

A

erythrocytes

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38
Q

what is the function of red blood cells?

A

to carry oxygen from the lungs to all of the cells in the body

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39
Q

how are red blood cells adapted for their function?

A
  • they have a biconcave shape to give a larger surface area for absorbing oxygen
  • they don’t have a nucleus which allows more room to carry oxygen
  • they contain haemoglobin
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40
Q

what is haemoglobin?

A

a red pigment in red blood cells which contains iron

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41
Q

how does haemoglobin release oxygen to the cells?

A

in the lungs haemoglobin binds to oxygen to form oxyhaemoglobin.

in body tissues, the oxyhaemoglobin breaks into haemoglobin and oxygen to release oxygen to the cells

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42
Q

what are the two types of white blood cells?

A

phagocytes and lymphocytes

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43
Q

what are phagocytes?

A

white blood cells which can change shape to engulf microorganisms

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44
Q

what is the process called when phagocytes change shape to engulf microorganisms?

A

phagocytosis

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45
Q

what are lymphocytes?

A

white blood cells which produce antibodies against microorganisms. some produce antitoxins as well.

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46
Q

why do some lymphocytes produce antitoxins?

A

to neutralise any toxins produced by microorganisms

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47
Q

state what your white blood cells do when you have an infection

A

the white blood cells multiply to fight the infection

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48
Q

when would a blood test show a high white blood cell count and why?

A

when you have an infection, this is because the white blood cells multiply to fight the infection off

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49
Q

do white blood cells contain a nucleus?

A

yes, unlike red blood cells

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50
Q

what are platelets?

A

small fragments of cells

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51
Q

do platelets have a nucleus?

A

no

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52
Q

what is the function of platelets?

A

to help the blood clot at a wound

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53
Q

why do wounds need to clot?

A

to stop the blood pouring out of the wound and to stop microorganisms from entering the body

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54
Q

what can a lack of platelets cause?

A

excessive bleeding and bruising

55
Q

what causes excessive bleeding and bruising?

A

a lack of platelets in the blood

56
Q

what is plasma?

A

a pale straw-coloured liquid which carries everything in the blood

57
Q

what does plasma carry in the blood specifically?

A
  • red blood cells,
  • white blood cells,
  • platelets,
  • nutrients such as glucose and amino acids (the soluble products of digestion absorbed from the gut and taken to the cells in 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.)
58
Q

what are the three different types of blood vessel?

A

arteries, capillaries, and veins

59
Q

what is the function of arteries?

A

to carry the blood away from the heart

60
Q

what is the function of capillaries?

A

to assist in the exchange of materials at the tissues

61
Q

what is the function of veins?

A

to carry the blood to the heart

62
Q

what adaptations do arteries have for their function?

A
  • strong and elastic walls because the heart pumps the blood out at a high pressure
  • thick walls compared to the lumen
  • thick layers of muscle to strengthen them and elastic fibres to allow them to stretch and spring back
63
Q

what is the lumen?

A

the hole down the centre of arteries, capillaries, and veins

64
Q

what do arteries branch into?

A

capillaries

65
Q

what adaptations do capillaries have for their function?

A
  • they are very narrow to squeeze into the gaps between cells to carry the blood very close to the cells for the exchange of substances
  • have permeable walls for the diffusion of substances into and out of the capillaries
  • walls are usually only one cell thick, increasing the rate of diffusion by decreasing the distance over which it occurs
66
Q

what do capillaries do?

A

supply food and oxygen and remove waste such as carbon dioxide

67
Q

do capillaries contain a nucleus?

A

yes

68
Q

what joins up to form veins?

A

capillaries

69
Q

what do capillaries eventually join up to form?

A

veins

70
Q

what adaptations do veins have for their function?

A
  • the walls are not as thick as the artery walls because the blood is at a lower pressure in the veins
  • have larger lumen to help blood flow despite the lower pressure
  • have valves to keep the blood flowing in the correct direction
71
Q

what type of circulatory system do mammals have?

A

a double circulatory system

72
Q

what is a double circulatory system?

A

when the heart pumps blood around the body in two circuits

73
Q

what happens in the first circuit of a double circulatory system?

A

the heart pumps deoxygenated blood to the lungs to take on oxygen, and oxygenated blood then returns to the heart

74
Q

what happens in the second circuit of a double circulatory system?

A

the heart pumps oxygenated blood to all of the other organs in the body to deliver oxygen to the body cells, deoxygenated blood then returns to the heart

75
Q

what type of circulatory system do fish have?

A

a single circulatory system

76
Q

what happens in a single circulatory system?

A

deoxygenated blood from the [fish’s] body travels to the heart, which then pumps the blood around the body again in a single circuit via the gills where oxygen is picked up

77
Q

how many chambers does a fish’s heart have?

A

two

78
Q

how many chambers does a mammalian heart have?

A

four

79
Q

how many major blood vessels does a mammalian heart have?

A

four

80
Q

which ventricle has a much thicker wall than the other?

A

the left ventricle has a much thicker wall than the right ventricle

81
Q

why does the left ventricle have a much thicker wall than the right ventricle?

A

because the left ventricle needs more muscle because it has to pump blood around the whole body at high pressure but the right ventricle only has to pump blood to the lungs

82
Q

what is the purpose of valves?

A

to prevent the backflow of blood in the heart

83
Q

what is cardiac output?

A

the total volume of blood pumped by a ventricle every minute

84
Q

how can you calculate cardiac output?

A

heart rate x stroke volume

85
Q

what are the units for cardiac output?

A

cm³ min⁻¹

86
Q

what is heart rate?

A

the number of beats per minute (bpm)

87
Q

what is the stroke volume?

A

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

88
Q

what are the units for heart rate?

A

beats per minute (bpm)

89
Q

what are the units for stroke volume?

A

cm³

90
Q

what is the formula triangle for heart rate, cardiac output and stroke volume?

A

cardiac output
———————
heart x stroke
rate volume

91
Q

where dow energy come from?

A

food and it is released by respiration

92
Q

what is respiration?

A

the process of transferring (releasing) energy from the breakdown of organic compounds (usually glucose)

NOT breathing in and breathing out

93
Q

where does respiration happen?

A

in every cell of all living organisms

94
Q

how frequently does respiration happen?

A

continuously

95
Q

what type of reaction is respiration and why?

A

an exothermic reaction because energy is transferred o the environment

96
Q

in what form is some of the energy from respiration transferred to the environment?

A

in the form of heat energy

97
Q

what are the two types of respiration?

A

aerobic and anaerobic respiration

98
Q

what are organic compounds?

A

compounds containing carbon, these include carbohydrates, lipids and proteins

99
Q

what is energy used for?

A
  • metabolic processes (e.g. making larger molecules from smaller ones - proteins from amino acids)
  • contracting muscles in animals
  • maintaining a steady body temperature in mammals and birds
100
Q

when does aerobic respiration happen?

A

when there is plenty of oxygen available

101
Q

what does “aerobic” mean?

A

“with oxygen”

102
Q

which way is the most efficient way to transfer energy from glucose, aerobic respiration or anaerobic respiration?

A

aerobic respiration

103
Q

what is the equation for aerobic respiration?

A

glucose + oxygen -> carbon dioxide + water

C₆H₁₂O₆ + 6O₂ -> 6CO₂ + 6H₂O

104
Q

when does your body do anaerobic respiration?

A

when you do very vigorous exercise your body can’t supply enough oxygen to the muscles for aerobic respiration, even though your heart rate and breathing rate increase to the maximum. the muscles have to start respiration get anaerobically as well.

105
Q

what does “anaerobic” mean?

A

“without oxygen”

106
Q

what happens in anaerobic respiration?

A

the glucose is only partially broken down and lactic acid is also produced

107
Q

what happens when lactic acid is produced in anaerobic respiration?

A

the lactic acid builds up in the muscles, becomes painful and leads to cramp

108
Q

what is the equation for anaerobic respiration in animals?

A

glucose -> lactic acid

109
Q

what is the equation for anaerobic respiration in plants?

A

glucose -> ethanol + carbon dioxide

110
Q

what is an example of plants which do anaerobic respiration?

A

fungi such as yeast

111
Q

name three things you could use in an experiment to measure the rate of respiration

A

live woodlice, germinating peas, germinating beans, mealworms

112
Q

describe the step-by step method for measuring the rate of respiration using a respirometer.

A

1) add some soda lime granules to two test tubes.
2) place a ball of cotton wool on top of the soda lime granules in both tubes to protect you and the organisms from the soda lime,
3) put some live woodlice/mealworms/ germinating peas in top of the cotton wool in one test tube and glass beads with the same mass as the woodlice/mealworms/germinating peas on top of the cotton wool in the other tube as a control.
4) insert a bung and capillary tube (with a scale) into both test tubes
5) place both test tubes into a rack in a water bath at a set temperature (around 15°C), it is best to tilt the rack slightly so that the capillary tubes hang over the side of the water bath at an angle
6) wait for five minutes to allow the organisms to adjust to the temperature of the water bath
7) add some coloured liquid to the capillary tubes
8) during the time in the water bath there will be a decrease in the volume of air in the test tube containing the organisms because the organisms use up oxygen in the tube as they respire but the carbon dioxide will be absorbed by the soda lime. the decrease in the volume of air reduces the pressure in the tube which causes the coloured liquid to move towards the test tube containing the organisms.

mark the position of the coloured liquid in the tube and time for five minutes,

9) mark the position of the coloured liquid again and measure the distance it has travelled
10) repeat the experiment at different temperatures

113
Q

what does soda lime do in the experiment to measure the rate of respiration using a respirometer?

A

it absorbs the CO₂ produced by the respiring woodlice/ germinating peas/germinating peas in the experiment

114
Q

what hazard is soda lime? what precautions should you take to be safe with it?

A

soda lime is corrosive, wear safety goggles and gloves when handling it to protect your eye and skin

115
Q

what can you use as a substitute for soda lime in the experiment to measure the rate of respiration using a respirometer?

A

cotton wool soaked in a few drops of potassium hydroxide solution to absorb the carbon dioxide

116
Q

is diffusion a fast or slow process?

A

slow

117
Q

if organisms are different sizes, do the rates of diffusion differ?

A

no, the rate of diffusion is always the same - no matter what size the organism is

118
Q

why are cells so small?

A

because the distance for diffusion needs to be short so the substances can diffuse quickly

119
Q

how many times does the blood pass through the heart in one circulation of the body?

A

two (double circulatory system)

120
Q

what is an advantage which a double circulatory system has over a single circulatory system?

A

the blood is able to pumped at a greater pressure

121
Q

in which order does the blood flow through the chambers of the heart?

A

right atrium, right ventricle, left atrium, left ventricle

122
Q

which two chambers of the heart contain deoxygenated blood?

A

the right atrium and the right ventricle

123
Q

what are the two chambers of the heart which contain oxygenated blood?

A

the left atrium and the left ventricle

124
Q

what are the four major blood vessels of the heart?

A

pulmonary artery, aorta, vena cava, pulmonary vein

125
Q

in which order does blood flow through the four major blood vessels?

A

vena cava, pulmonary artery, pulmonary vein, aorta,

126
Q

describe the order of the blood flow through the heart

A
  • deoxygenated blood from the head and body enters through the vena cava, flows into the right atrium, passes through the tricuspid valve, enters the right ventricle, then goes up through the semi-lunar valves, through the pulmonary artery to the lungs.
  • the red blood cells collect oxygen from the lungs
  • then the oxygenated blood flows through the pulmonary vein and into the left atrium, through the bicuspid valve into the left ventricle where the blood receives a large push from the left ventricular wall, to go through the semi-lunar valves and out of the aorta to the carry oxygen to the rest of the body
127
Q

what is the vena cava?

A

a vein carrying deoxygenated blood, the vena cava is the main vein returning blood to the heart from the body

128
Q

what is the pulmonary artery?

A

an artery carrying deoxygenated blood, the pulmonary artery takes blood from the right ventricle to the lungs

129
Q

what is the pulmonary vein?

A

a vein carrying oxygenated blood, the pulmonary vein takes blood from the lungs to the left atrium

130
Q

what is the aorta?

A

an artery carrying oxygenated blood, the aorta takes blood from the left ventricle to the rest of the body

131
Q

what is the bicuspid valve?

A

the bicuspid valve is the valve between the left atrium and the left ventricle, it prevents the backflow of blood

132
Q

what is the tricuspid valve?

A

the tricuspid valve is between the right atrium and the right ventricle, it prevents the backflow of blood

133
Q

where do most of the reactions in aerobic respiration the place?

A

in the mitochondria

GCSE Edexcel Biology grade 9-1 course, topics 6-9 (3 decks)

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