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Energy for life - 3rd form Flashcards

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1
Q

what is cell respiration

A

the process of breaking down food molecules to release ATP - it is a series of chemical reactions

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2
Q

examples of uses of energy

A

cell division, building large molecules such as proteins, transporting molecules, maintaining body temperature, contraction of muscle cells which produces movement

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3
Q

describe the process of aerobic respiration

A

aerobic respiration used oxygen to break down glucose and release energy - some energy is released as heat, but most is trapped in a usable form of ATP

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4
Q

aerobic respiration word equation

A

glucose + oxygen –> carbon dioxide + water

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5
Q

aerobic respiration chemical equation

A

C6H12O6 + 6O2 –> 6CO2 +6H2O

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6
Q

what is anaerobic respiration

A

cells respiring without using oxygen

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7
Q

describe the process of anaerobic respiration

A

in anaerobic respiration, glucose is not completely broken down and so less ATP and therefore energy is released. it also produces toxic waste products, which must either be excreted or broken down

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8
Q

what is the advantage of anaerobic respiration

A

it allows cells to obtain a small amount of usable energy even when oxygen supply is limited

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9
Q

anaerobic word equation - fungi and plants

A

glucose –> ethanol + carbon dioxide

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10
Q

why is anaerobic respiration for fungi useful in food production

A
  • we use yeast in bread and alcohol production . we supply glucose and keep the yeast in low oxygen conditions so that cells respire anaerobically. the carbon dioxide produced forms bubbles in bread dough which causes it to rise
  • the ethanol provides the alcohol content in beer and wine
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11
Q

anaerobic word equation - animals

A

glucose –> lactic acid

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12
Q

when is anaerobic respiration used in animals

A

this process occurs in muscle cells when there is a shortage of oxygen like in intensive exercise. if muscles are worked very hard, they need large quantities of energy, more than can be provided by aerobic respiration. the glycogen stored in muscle cells is broken down into glucose. this is respired anaerobically, providing an additional energy supply

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13
Q

what does lactic acid build up cause

A

lactic acid builds up, causing cramps, and it diffuses from muscles into the blood. in high concentrations lactic acid is toxic, so it is transported to the liver where it is oxidised. this uses oxygen - we keep breathing heavily after exercise to supply the extra oxygen needed to dispose of the lactic acid in our bodies

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14
Q

what is oxygen debt

A

the volume of oxygen needed to oxidise the lactic acid

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15
Q

what do we want to show when investigating respiration

A

only living things respire

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16
Q

what happens in the pea experiment

A

as the peas start to grow, they respire releasing heat. the thermos flask is insulated, so heat is not transferred to the surroundings and we can measure the change in temperature. we only see a temperature rise in one thermos as the peas in the other are dead as they have been boiled. in both thermos flasks the peas are soaked in Milton solution (bleach) which kills any bacteria that would respire and therefore affect the results

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17
Q

how can we prove carbon dioxide is produced in the pea experiment

A

by using gas delivery tubes to collect any gas that was produced. this gas can then be bubbled through limewater. only the gas from the flask with the living peas would turn the limewater cloudy which shows that carbon dioxide is produced

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18
Q

equipment for the pea experiment

A

two thermos flasks with cotton wool plugs and thermometers
one thermometers with pea seeds and the other with dead pea seeds both soaked in Milton solution

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19
Q

what indicator can we use when experimenting respiration with insects

A

this indicator is red, but turns yellow when carbon dioxide concentration increases. carbon dioxide reacts with water to form a weak acid

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20
Q

equipment for the respiration insect experiment

A

two test tubes with a tightly fitting bung and hydrogen carbonate indicator
one test tube with a support and an insect on top of it

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21
Q

what equipment is used to investigate anaerobic respiration in yeast when looking at the time taken for limewater to become cloudy

A

a boiling tube and a test tube connected by a delivery tube
the boiling tube has glucose and yeast suspension with a thin layer of oil on top and a bung with a delivery tube coming out of it
the delivery tube goes into the test tube which has limewater in it

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22
Q

what equipment is used to measure the volume of carbon dioxide produced when investigating anaerobic respiration in yeast

A

a boiling tube with a bung and delivery tube coming out of it
in the boiling tube there is glucose and yeast suspension which has a thin layer of oil on top
the delivery tube is connected to a gas syringe

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23
Q

what is diffusion

A

the random movement of particles from an area of high concentration to an area of lower concentration

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24
Q

what are the four main factors that affect the rate of diffusion

A

temperature, concentration gradient, distance, surface area : volume

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25
Q

how does temperature affect the rate of diffusion

A

at higher temperatures, molecules have more kinetic energy and so move faster meaning that diffusion therefore occurs faster

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26
Q

how does concentration gradient affect the rate of diffusion

A

if there is a very large difference in concentration between areas, molecules will diffuse from the higher to the lower concentration quickly. if the concentration gradient difference is small, diffusion will happen more slowly

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27
Q

how does surface are : volume affect the rate of diffusion

A

a larger surface area speeds up the rate of diffusion as there are more oppurtunities for the molecules to move, which is why surfaces such as alveoli in lungs are so large. surface area to volume ratio is more significant, as the two counteract (oppose) each other: an efficient exchange surface has a surface area which is very large compared to the distance the molecules must travel
.SA:V is increased when structures are small

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27
Q

how does distance affect the rate of diffusion

A

diffusion takes longer if the molecules have to travel further (especially as molecules do not travel in s straight line, slowing the process)

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28
Q

where is the gas exchange system located in the body

A

in the thorax - the upper part of the body

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29
Q

what happens when we breathe

A

air passes down the trachea. the tube is surrounded by C-shaped rings of cartilage which keep the trachea open but make swallowing easier

the trachea splits to form the two bronchi - these tubes lead to the lungs. the bronchi are also surrounded by the cartilage rings

the bronchi divide, or branch, into smaller and smaller tubes called bronchioles, which carry air deep into the thorax

at the end of each bronchiole there are microscopic air sacs called the alveoli which are the site of gas exchange

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30
Q

what are the lungs surrounded by

A

pleural membrane which forms a double layer between the lungs and the thorax walls

in between the membranes there is a thin layer of pleural fluid. together they form an air tight seal and prevent the lungs from sticking to the thorax walls as they inflate and deflate

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31
Q

what do the ribs do

A

help to protect the organs in the thorax

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32
Q

where are the intercoastal muscles

A

between the ribs

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33
Q

what do the intercoastal muscles do

A

help to connect the bones and are important in moving air into and out of the lungs

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34
Q

what is below the lungs

A

the diaphragm

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35
Q

what does the diaphragm do

A

this domed sheet of muscle and fibrous tissue is also important in moving air into and out of the lungs

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36
Q

what is ventilation

A

the process of moving air into and out of the lungs (inhalation and exhalation) - moving air relies on difference in air pressure between the lungs and the atmosphere

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37
Q

what happens to the diaphragm, intercoastal muscles and rib cage during inhalation

A

the diaphragm contracts,moving down and flattening
intercoastal muscles contract, moving the rib cage up and out

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38
Q

what happens to the volume and air pressure during inhalation

A

the volume of the thorax increases and air pressure in the thorax falls

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39
Q

how does air move into the lungs during inhalation

A

air pressure in the thorax becomes less than atmospheric pressure, causing air to move into the lungs

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40
Q

what happens to the diaphragm, intercoastal muscles and rib cage during exhalation

A

the diaphragm relaxes, moving up and doming
intercoastal muscles relax, moving the rib cage down and in

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41
Q

what happens to the volume and air pressure during exhalation

A

the volume of the thorax decreases and air pressure in the thorax rises

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42
Q

how does air move out of the lungs during exhalation

A

air pressure in the thorax becomes more than the atmospheric pressure, causing air to move out of the lungs

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43
Q

where does gas exchange occur

A

in the alveoli which is the air sacs

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44
Q

what happens during gas exchange in the alveoli

A

oxygen diffuses from the air into the red blood cells, where it binds with the haemoglobin for transport. carbon dioxide, dissolved in the plasma, diffuses from the blood into the alveolus

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45
Q

how is the structure of the alveoli specialised for efficient gas exchange

A

there is a large number of alveoli in the lungs which means there is a large surface area which increases the rate of diffusion

each alveolus is surrounded by a network of capillaries, which constantly carry deoxygenated blood to the alveolus and move oxygenated blood away - this maintains a high concentration gradient and so speeds up diffusion

the walls of the alveoli are only one cell thick so the capillary walls are immediately next to the alveli and are again only one cell thick - this means that gases only need to move a very samll distance which speeds up the rate of diffusion

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46
Q

what does the composition of inhaled and exhaled air experiment look at

A

this investigation compares the content of inhaled and exhaled air, using a T-tube arrangement going from a mouthpiece into two conical flasks or boiling tubes. the inhaled and exhaled air bubbles through the indicator as the student breathes in and out

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47
Q

what indicators could you use to compare inhaled and exhaled air

A

limewater or hydrogen-carbonate

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48
Q

what colour would limewater turn for inhaled air

A

stays colourless

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49
Q

what colour would limewater turn for exhaled air

A

turns milky white

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50
Q

what colour would hydrogen carbonate indicator turn for inhaled air

A

stays red

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51
Q

what colour would hydrogen carbonate indicator turn for exhaled air

A

turns yellow

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52
Q

what experiment could you use to see the effect of exercise on breathing rate

A

you can compare breathing rates before and after exercise by watching and counting the number of breaths someone takes in one minute (or 30s) at rest and then ask your subject to exercise (such as jogging on the spot for 5 mins) and count the number of breaths they take in the during the first minute after their exercise

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53
Q

how would you reach a valid conclusion for the effect of exercise on breathing

A

you would need to carry out the experiment on lots of people and control many variables (such as age, gender, fitness, type of exercise, length of exercise)

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54
Q

As well as the depth of each breath, what other affect on breathing does exercise have

A

during exercise breathing rate increases in response to the increased concentration of carbon dioxide in the blood

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55
Q

what happens as a result of breathing rate increasing

A

we excrete carbon dioxide more rapidly. oxygen can also diffuse into the blood at a faster rate because there is a higher concentration gradient. this, along with an increase in heart rate, supplies more oxygen to the muscles for aerobic respiration.

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56
Q

what happens to breathing rate after exercise if our muscles respire anaerobically

A

our breathing rate will remain high after exercise to supply the extra oxygen needed to oxidise the lactic acid

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57
Q

what is one of the carcinogens in tobacco smoke and what is its affect

A

tar and it contains chemicals which can alter the DNA and increase the risk of cancer

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58
Q

what does carbon monoxide do

A

irreversably binds to the haemoglobin, forming carboxyhaemoglobin, and so reducing the amount of oxygen transported by the blood

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59
Q

what would happen if a pregnant woman smoked

A

the baby would receive less oxygen and as a result is likely to weigh less at birth which can cause other problems

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60
Q

what do goblet cells do

A

produce mucus which traps dust and pathogens

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61
Q

what do the chemicals in tobacco smoke do / effects of smoking

A

-the chemicals destroy cilia, reducing their number

-mucus production increases in response to the smoke

-smoker’s cough and increased risk of infections– caused by the mucus cannot be moved out of the airways quickly and so builds up

-bronchitis is a result of the build-up of infected mucus in the bronchi and bronchioles

  • emphysema is caused due to damaged alveoli – when smoke reaches the alveoli their walls break down in pieces forming large irregular air spaces which decreases the surface area for gas exchange so less oxygen diffuses into the blood
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62
Q

carbohydrate food source

A

bread, potatoes,rice, cereals, fruit

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63
Q

function of carbohydrates

A

fuel for respiration

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64
Q

protein food source

A

meat,eggs, fish, quinoa, quorn

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65
Q

function of proteins

A

growth and repair of cells and tissues
fuel for respiration

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66
Q

lipids food source

A

butter, cooking oil, cream, avocados

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67
Q

function of lipids

A

(thermal and electrical) insulation
fuel for respiration

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68
Q

what is the most common substrate

A

carbohydrate glucose

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69
Q

what is glucose stored as in plants

A

starch

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70
Q

what is glucose stored as in animals

A

glycogen

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71
Q

examples of energy being used to keep our body running

A

heart beating, transport nutrients (active transport) and repair our cells

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72
Q

what is energy measured in

A

kilojoules (kJ) or joules (J)

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73
Q

how can you measure the energy content of a food

A

you can burn a known mass of the food and use the thermal energy released to heat the water

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74
Q

describe how you measure the energy content of a food sample

A
  • measure the mass of food (on a balance)
  • measure the same volume of water (in a measuring cylinder) as the mass of food
  • pour water into a boiling tube and record the starting temperature
    -light the food on a metal, mounted needle and hold it under the boiling tube until it is completely burned
  • record the final temperature to find the temperature change
  • calculate the total energy in J = 4.2J x volume of water x increase in temperature (degrees C)
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75
Q

what is the function of iron in the body

A

forms the part of haemoglobin which binds to oxygen

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76
Q

iron food source

A

red meat, liver,spinach

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77
Q

deficiency disease of iron

A

Anaemia

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78
Q

what is the function of calcium in the body

A

needed to form bones and teeth

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79
Q

calcium food source

A

milk and dairy products, fish, fresh vegetables

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80
Q

deficiency disease of calcium

A

rickets

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81
Q

vitamin A use in the body

A

making a chemical in the retina and also protects the surface of the eye

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82
Q

effect of vitamin A deficiency

A

night blindness and damaged cornea

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83
Q

vitamin A food source

A

fish liver oil, liver, butter, carrots

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84
Q

vitamin C use in the body

A

needed for cells and tissues to stick together

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85
Q

effect of vitamin C deficiency

A

scurvy

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86
Q

vitamin C food source

A

fresh fruit and vegetables

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87
Q

vitamin D use in the body

A

needed to absorb Calcium and Phosphate ions from food

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88
Q

effect of vitamin D deficiency

A

rickets, caused by weak bones

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89
Q

vitamin D food source

A

dairy products, oily fish

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90
Q

why is water needed in the body

A

water is an essential solvent which is used to transport components of blood and is crucial for temperature regulation (such as sweating)

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91
Q

why is fibre needed in the body

A

fibre is plant material that you cannot digest,it is mainly a chemical called cellulose. fibre helps the movement of food through the intestine, preventing constipation and bowel cancer

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92
Q

fibre food sources

A

fruit and vegetables along with grains (wheat, oats etc) are all good sources of fibre as they all contain cellulose

93
Q

what processes happen to food in the alimentary canal

A

food is ingested, digested, absorbed and egested from this canal for the purpose that the food can be assimilated

94
Q

what is ingestion

A

taking food in through themouth and swallowing

95
Q

what is digestion

A

breaking down large insoluble molecules in food into smaller pieces (physical digestion) and smaller, soluble molecules (chemical digestion)

96
Q

what is absorption

A

movement of small soluble molecules out of the gut and into the blood by diffusion and active transport

97
Q

what is egestion

A

passing out undigested food through the anus

98
Q

what is assimilation

A

building larger biological molecules from the small soluble molecules in all cells

99
Q

what two things are called the small intestine together

A

duodenum and the ileum

100
Q

what two things are called the large intestine together

A

colon and the anus

101
Q

what is the first structure in the alimentary canal

A

the mouth

102
Q

where does ingestion take place

A

the mouth

103
Q

what is mechanical digestion

A

food is broken up into smaller pieces in the mouth by chewing which increases the surface area for enzymes and also prevents discomfort when swallowing

104
Q

what is chemical digestion

A

saliva is released into the mouth by the salivary glands which makes the food easier to swallow, and also contains the enzyme amylase

105
Q

what does amylase break starch down into

A

maltose

106
Q

starch break down in the mouth chemical chain

A

starch –amylase–> maltose

107
Q

what happens to amylase at the stomach

A

amylase works best at a neutral pH, so it is denatured when it reaches the stomach and stops working

108
Q

what happens before swallowing

A

the food is shaped into a ball by the tongue and moved towards the back of the mouth - this ball is called the bolus

109
Q

what is the flap which blocks food from entering the trachea called

A

the epiglottis

110
Q

what movement pushed food down the oesophagus

A

peristalsis

111
Q

how does peristalsis occur in the oesophagus

A

two sets of muscles push the food down the oesophagus. the circular muscles contract behind the bolus pushing it along. when the longitudinal muscles contract they make the oesophagus wider

112
Q

what enzyme do the gastric glands in the stomach release

A

pepsin and hydrochloric acid

113
Q

what are peptides

A

shorter chains of amino acids

114
Q

protein breakdown in the stomach chemical chain

A

protein –pepsin–> peptide

115
Q

what mixes the contents of the stomach

A

contraction of the stomach causes mixing of its contents, maximising contact between enzymes and food

116
Q

what are pepsin’s optimum conditions

A

an acidic pH

117
Q

how do the conditions of the stomach become acidic

A

the release of hydrochloric acid by the gastric glands

118
Q

what does the hydrochloric acid do to the food in the stomach

A

kills many bacteria and fungi which may be oresent in the food eaten

119
Q

what processes occur in the small intestine

A

digestion and absorption

120
Q

where does digestion happen

A

the duodenum

121
Q

what is the final site of chemical digestion

A

the duodenum

122
Q

what does the pancreas do

A

makes several enzymes and secretes them into the duodenum

123
Q

what enzymes does the pancreas secrete

A

trypsin, amylase, lipase

124
Q

protein breakdown in the duodenum chemical chain

A

protein –trypsin–> peptide

125
Q

starch breakdown in the duodenum chemical chain

A

starch –amylase–> maltose

126
Q

lipid breakdown in the duodenum chemical chain

A

lipid (fat) –lipase–> glycerol + 3 fatty acids

127
Q

what does the duodenum wall contain

A

glands which make enzymes and secretes them into the duodenum

128
Q

what enzymes does the duodenum wall secrete

A

maltase and peptidase

129
Q

maltose breakdown in the duodenum chemical chain

A

maltose –maltase–> glucose

130
Q

peptide breakdown in the duodenum chemical chain

A

peptide –peptidase–> amino acids

131
Q

where is bile produced

A

the liver

132
Q

where is bile stored

A

the gall bladder

133
Q

where is bile released

A

the duodenum

134
Q

what are the two functions of bile

A
  • neutralises the stomach acid - enzymes in the duodenum work best at pH 7-8
  • emulsifies lipids - breaks large droplets into smaller droplets, increasing the surface area for lipase to digest the fats
135
Q

what process stops and what other process begins once the ileum is reached

A

digestion is over and absorption begins

136
Q

what are the many finger-like projections in the folds of the ileum called

A

villi

137
Q

what are the small soluble molecules absorbed through in the ileum

A

villi

138
Q

how are some of the small soluble molecules absorbed in the ileum

A

some are absorbed by diffusion however some such as glucose are also absorbed via active transport, which moves particles against a concentration gradient using ATP

139
Q

how does the ileum increase the rate of diffusion

A
  • large surface area - folding of ileum, villi and microvilli all increase the surface area
  • short diffusion distance - the villi walls are one cell thick
  • high concentration gradient - provided by capillary network and lacteals removing absorbed molecules
140
Q

what occurs at the colon

A

the colon is the site for the reabsorption of water

141
Q

where are faeces stores

A

the rectum

142
Q

where are faeces egested

A

the anus

143
Q

what is excretion

A

the removal of waste substances produced by chemical reactions in the body (for example carbon dioxide removed by the lungs and urea removed by kidneys and sweat)

144
Q

what is the enzyme group that acts upon carbohydrates

A

carbohydrases

145
Q

what is the enzyme group that acts upon proteins

A

proteases

146
Q

what is the enzyme group that acts upon lipids

A

lipases

147
Q

how does temperature affect an enzyme controlled reaction

A

the higher temperature gives the enzymes and substrates more kinetic energy. they move faster and collide more often, so you get more reactions per second

148
Q

what happens above the optimum temperature

A

the heat breaks the forces holding the proteins in the correct shape. the shape of the enzyme therefore changes which means the active site changes shape so that it is no longer complimentary to the substrate. the substrate cannot bind to the active site and the reaction cannot occur meaning the enzyme has been denatured

149
Q

what is the pH inside cells

A

neutral - pH 7

150
Q

what happens to the enzyme if the pH of the environment changes

A

it can affect the shape of the enzyme. the active site changes shape so it is no longer complimentary to the substrate. the enzyme is denatured and the reaction can no longer occur

151
Q

how can you investigate the effect of temperature on enzymes - for example amylase but you can use any enzyme

A

mix starch suspension and amylase in a boiling tube and heat in a water bath at a certain temperature
every minute from the point of mixing take one drop of this mixture and add it to one drop of iodine solution in the spotting tile
when digestion is complete and no starch is present, iodine solution will stay orange and not turn blue black
repeat this using baths of different temperatures

152
Q

how can you investigate the effect of pH on enzymes

A

you can alter the pH by adding different volumes of a weak alkali or a weak acid and use universal indicator to determine the pH of the solution each time
add the enzyme and what it breaks down into a conical flask and measure the amount the reaction produces in 5 minutes such as measuring the gas produces in a gas syringe

153
Q

what is the blood vessel that transports blood to the heart

A

pulmonary vein

154
Q

what blood vessel transports blood from the heart

A

aorta

155
Q

what is the blood vessel that transports blood to the liver

A

hepatic artery

156
Q

what is the blood vessel that transports blood to the gut

A

mesentric artery

157
Q

what is the blood vessel that transports blood to the kidneys

A

renal artery

158
Q

what is the blood vessel that transports blood from the kidneys

A

renal vein

159
Q

what is the blood vessel that transports blood from the gut

A

hepatic portal vein

160
Q

what is the blood vessel that transports blood from the liver

A

hepatic vein

161
Q

what is the blood vessel that transports blood to the heart

A

vena cava

162
Q

what is the blood vessel that transports blood to the lungs

A

pulmonary artery

163
Q

what is pulmonary circulation

A

deoxygenated blood is pumped to the lungs and oxygenated blood returns back to the heart

164
Q

what is systemic circulation

A

oxygenated blood is pumped to all the other organs of the body and deoxygenated blood returns back to the heart

165
Q

what four chambers is the heart divided into

A

right atrium
right ventricle
left atrium
left ventricle

166
Q

what is the muscular wall of the atria like

A

thin muscular walls

167
Q

what is the muscular wall of the ventricles like

A

thick muscular walls

168
Q

why are the left and right sides of the heart separated by the septum

A
  • the right side of the heart pumps deoxygenated blood to the lungs
  • the left side of the heart pumps oxygenated blood to the body
169
Q

why is the left ventricle wall thicker than the wall of the right ventricle

A

to allow it to pump blood at higher pressures so that the blood can travel around the whole body

170
Q

describe the heart contraction and relaxation process

A

the two sides of the heart contract and relax at the same time to pump blood. the atria contract, emptying blood into the ventricles. the ventricles then contract, pushing blood into the arteries and around the body. valves close to ensure blood flows in the correct direction

171
Q

why does heart rate increase during exercise - short

A

so that more blood can travel to the muscles as they need more glucose and oxygen for aerobic respiration

172
Q

what are changes in heart rate controlled by

A

nerve impulses from a part of the brain called the medulla

173
Q

why does heart rate increase during exercise - long

A
  • when exercise starts the muscles produce more carbon dioxide in aerobic respiration
  • sensors in the aorta and carotid artery detect this increase
  • they send nerve impulses to the medulla
  • the medulla responds by sending nerve impulses along the accelerator nerve
  • the accelerator nerve increases the heart rate
  • more blood is supplied to the muscles to meet the demands of increased aerobic respiration
174
Q

which nerve sends electrical impulses to decrease heart rate at rest

A

the decelerator nerve

175
Q

what happens to heart rate when we are stressed (angry or afraid)

A

heart rate increases because it is triggered by the secretion of the hormone adrenaline

176
Q

what type of tissue is blood

A

a complex tissue

177
Q

what does blood consist of

A

plasma, platelets and red and white blood cells

178
Q

what is plasma

A

straw coloured liquid
transports blood cells and many other substances, including: dissolved nutrients such as glucose and amino acids; dissolved waste products including urea and carbon dioxide; hormones; proteins; heat energy

179
Q

what are red blood cells

A

small red cells
transport oxygen that is bound to haemoglobin

180
Q

what are platelets

A

cell fragments
release chemicals when the blood is exposed to air, which cause soluble fibrinogen to be converted to insoluble fibrin. fibrin forms a mesh, which traps platelets and red blood cells (this is a clot/ scab)

181
Q

what are phagocytes (white blood cells)

A

larger cells with a multi-lobed nucleus
engulf and digest pathogens (microorganisms which cause disease)

182
Q

what are lymphocytes (white blood cells)

A

cells with a very large nucleus
make and release antibodies, which bind to and destroy pathogens

183
Q

what do red blood cells contain

A

haemoglobin

184
Q

how are red blood cells specialised for their job

A
  • red blood cells contain haemoglobin, a protein which combines with oxygen to form oxyhaemoglobin which transports oxygen to respiring cells
  • they have no nucleus, meaning that more haemoglobin can be packed into each cell and so more oxygen can be transported
  • they are bioconcave which increases their surface area: volume ratio and decreases the distance to the centre of the cell which increases the rate of diffusion
185
Q

what happens if platelets are exposed to oxygen

A

they release chemicals which start the clotting process

186
Q

what do the chemicals released in the clotting process cause

A

these chemicals cause the soluble plasma protein fibrinogen to be changed into the insoluble fibrous protein fibrin, the fibrin forms a network of fibres across the cut, which trap platelets and red blood cells, this forms a clot, or scab, which prevents further loss of blood. it also acts as a barrier to prevent the entry of pathogens

187
Q

how can clots form in blood vessels

A

if plaques cause red blood cells to be broken - this can cause heart attacks

188
Q

what do arteries do

A

arteries carry blood away from the heart - this blood is flowing at high pressure

189
Q

what do veins do

A

veins return blood into the heart - this blood is flowing at low pressure

190
Q

what do capillaries do

A

capillaries are tiny vessels and there are lots of them, they carry blood through all the tissues and are the site of exchange of materials by diffusion

191
Q

structure of an artery

A

thick outer wall
thick layer of elastic tissue
thick layer of muscular tissue

192
Q

what is the function of the thick outer wall of the artery

A

can transport blood at high pressure without bursting

193
Q

what is the function of the thick layer of elastic tissue of the artery

A

allows artery to stretch and recoil to keep blood flowing at high pressure

194
Q

what is the function of the thick layer of muscular tissue of the artery

A

helps to control flow of blood by widening (dilating) and narrowing (constricting)

195
Q

structure of a vein

A

fairly thin outer wall
thin layer of muscle and elastic tissue
semilunar valves

196
Q

what is the function of the thin outer wall of the vein

A

blood is flowing at lower pressure so thick wall is not needed

197
Q

what is the function of the thin layer of muscle and elastic tissue

A

the wall can contract to keep blood flowing

198
Q

what is the function of the semilunar valves of the vein

A

prevents blood flowing backwards

199
Q

what is the structure of the capillary

A

wall is one cell thick

200
Q

what is the function of the wall being one cell thick

A

short distance for diffusion of substances from blood into tissues

201
Q

what do the coronary arteries do

A

the coronary arteries supply the heart muscle with blood. this blood provides the glucose and oxygen needed for aerobic respiration and removes the carbon dioxide produced by aerobic respiration

202
Q

what happens if there are a lot of saturated fats in your diet

A

if you have lots of saturated fats in your diet, fatty deposits will build up in the artery walls. the fatty deposits narrow the lumen of the artery. this is a particular problem in the narrow coronary arteries as it restricts blood flow to the heart muscles cells

the fatty deposits cause the heart muscle cells to receive less blood. this means that the heart muscle cells receive less oxygen (and glucose) for aerobic respiration. as a result aerobic respiration reduces and anaerobic respiration increases in the heart muscle cells. lactic acid will build up due to the increase in anaerobic respiration, poisoning the heart muscle cells and causing heart attacks

203
Q

what are the certain risk factors which make coronary heart disease more likely

A

diet - eating lots of saturated fat increases blood cholesterol and increases the risk of fatty deposits
smoking - increases blood pressure and increases the risk of fatty deposits forming
high blood pressure - damages the artery lining and increases the risk of fatty deposits forming. high salt levels in your diet increase the risk of high blood pressure
obesity - being obese will increase blood pressure and may be linked to poor diet
lack of exercise - causes high blood pressure

204
Q

what is light energy absorbed by in plants

A

chlorophyll

205
Q

what does photosynthesis occur in

A

plants as well as some bacteria and protoctista

206
Q

what is the word equation for photosynthesis

A

carbon dioxide + water –(light energy)–> glucose + oxygen

207
Q

what is the chemical equation for photosynthesis

A

6CO2 + 6H2O –> C6H12O6 + 6O2

208
Q

what does photosynthesis do

A

converts light energy into stored chemical energy, which can be used by the organism for respiration and for making other biological molecules

209
Q

what other molecules does glucose make

A

carbohydrates - starch for storage, sucrose for transport, fructose found in fruit, cellulose
DNA made of nucleotides
amino acids joined together to make proteins
lipids to make cell membranes and oils in seeds
chlorophyll
energy

210
Q

what mineral ions are used by plants to make molecules

A

Nitrates (NO3^-)
Magnesium (Mg)
Phosphates (PO4^3-)

211
Q

use of nitrates by plants

A

required to make amino acids (and so proteins) and nucleic acids (DNA and RNA)

212
Q

symptom of nitrate deficiency

A

stunted growth

213
Q

use of magnesium by plants

A

required to make chlorophyll

214
Q

symptom of magnesium deficiency

A

yellow leaves

215
Q

use of phosphates by plants

A

required to make nucleic acids (RNA and DNA); part of cell membrane

216
Q

symptoms of phosphates deficiency

A

poor root growth; purple younger leaves

217
Q

what factors affect photosynthesis

A

carbon dioxide
light intensity
increasing temperature

218
Q

why don’t we worry about water affecting the rate of photosynthesis

A

if the plant is short of water all the cells will be affected and the plant will wilt

219
Q

what is the factor which is in shortest supply called

A

the limiting factor

220
Q

carbon dioxide effect on rate of photosynthesis

A

by adding more carbon dioxide the reaction can happen faster, as there are more molecules to collide with enzymes. however, we reach a point when adding more carbon dioxide has no effect - there is a lack of energy

221
Q

light intensity effect on rate of photosynthesis

A

by adding a brighter light we increase the rate of photosynthesis, as there is more energy for the reaction to occur. this doesn’t last forever, as at high light intensities a different factor is limiting

222
Q

increasing temperature effect on rate of photosynthesis

A

increasing temperature speeds up the reaction. this is because the enzymes and substrates have more kinetic energy and collide more often. however, at high temperatures the rate of photosynthesis decreases and the reaction stops. this is because the enzymes carrying out the stages of photosynthesis have been denatured

223
Q

how is a leaf specialised for photosynthesis

A
  • the leaf has a large surface area and is thin, to maximise absorption of sunlight by photosynthetic cells. it also increases the number of stomata, so that carbon dioxide can diffuse quicker
  • the upper epidermis is transparent, allowing light to penetrate to the mesophyll
  • the palisade cells are long, thin and tightly packed. they contain large numbers of chloroplasts. this maximises the absorption of sunlight energy. the palisade mesophyll is the main sight of photosynthesis.
  • stomata allow gases to diffuse into the air spaces of the leaf. this provides a short diffusion distance for carbon dioxide
  • the xylem transports water ( absorbed in the roots) into the leaves. this then provides a short distance for water to diffuse into the photosynthesising cells.
  • the phloem vessels transport sugars made in photosynthesis to other parts of the plant
223
Q

components in the structure of a leaf

A

cuticle, upper epidermis, pallisade (mesophyll), xylem, phloem, spongey mesophyll, lower epidermis, guard cells, stoma

223
Q

how can you test leaves for starch

A

you can test leaves for starch using iodine solution on a leaf that has had its chlorophyll removed by boiling in ethanol

224
Q

describe the experiment of testing a leaf for starch

A
  • heat a leaf in boiling water for 1 min using a bunsen burner
  • place the leaf in a test tube of ethanol to remove its chlorophyll and place the test tube in the beaker of water
  • place the leaf back into the water to soften it and then place the leaf on a white tile
  • cover the leaf in iodine solution and if it turns black, starch is present
225
Q

how can a leaf be destarched

A

by placing it in the dark for 24 hours

226
Q

why does a leaf need to be destarched

A

the leaves need to be destarched so that they are free from starch at the start of the experiment meaning any starch in the leaf you test was produced from the glucose made in photosynthesis during your experiment

227
Q

how can the starch leaf experiment be used to show the conditions needed for photosynthesis

A

-to show that light is required, one leaf is covered with foil (or part of the leaf is covered); only the leaves (parts of the leaf) exposed to light will produce starch and turn black
- to show chlorophyll is required, a variegated leaf, in which the white parts of the leaf lacks chlorophyll, is used and starch is only produced in the areas that were green
- to show carbon dioxide is required one leaf of a plant is enclosed in a conical flask (or plastic bag) containing soda lime to absorb the carbon dioxide and this leaf is compared to another enclosed in a flask but without the soda lime. only the leaf that had access to carbon dioxide produces starch

228
Q

experiment to investigate how factors affect the rate of photosynthesis

A

a length of pondweed Elodea is put in a beaker of water and the number of bubbles released from the stalk in one minute is counted. the distance of a bench lamp can be moved to vary the light intensity, or differing masses of sodium bicarbonate to vary the carbon dioxide concentration

229
Q

how can you improve the method of investigating the factors affecting the rate of photosynthesis

A
  • putting the Elodea into a boiling tube of water and this can then be placed in a beaker, with a thermometer, to act as water bath. this reduces the temperature change during the experiment
  • collecting the gas in an inverted measuring cylinder and measure the volume of oxygen evolved per unit time
  • adding a fixed mass of sodium bicarbonate to the water, to provide a higher (constant) concentration of carbon dioxide

Biology - all note flashcards (7 decks)

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