Energy for life - 3rd form Flashcards
1
Q
what is cell respiration
A
the process of breaking down food molecules to release ATP - it is a series of chemical reactions
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
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
4
Q
aerobic respiration word equation
A
glucose + oxygen –> carbon dioxide + water
5
Q
aerobic respiration chemical equation
A
C6H12O6 + 6O2 –> 6CO2 +6H2O
6
Q
what is anaerobic respiration
A
cells respiring without using oxygen
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
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
9
Q
anaerobic word equation - fungi and plants
A
glucose –> ethanol + carbon dioxide
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
11
Q
anaerobic word equation - animals
A
glucose –> lactic acid
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
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
14
Q
what is oxygen debt
A
the volume of oxygen needed to oxidise the lactic acid
15
Q
what do we want to show when investigating respiration
A
only living things respire
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
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
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
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
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
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
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
23
Q
what is diffusion
A
the random movement of particles from an area of high concentration to an area of lower concentration
24
Q
what are the four main factors that affect the rate of diffusion
A
temperature, concentration gradient, distance, surface area : volume
25
how does temperature affect the rate of diffusion
at higher temperatures, molecules have more kinetic energy and so move faster meaning that diffusion therefore occurs faster
26
how does concentration gradient affect the rate of diffusion
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
27
how does surface are : volume affect the rate of diffusion
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
27
how does distance affect the rate of diffusion
diffusion takes longer if the molecules have to travel further (especially as molecules do not travel in s straight line, slowing the process)
28
where is the gas exchange system located in the body
in the thorax - the upper part of the body
29
what happens when we breathe
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
30
what are the lungs surrounded by
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
31
what do the ribs do
help to protect the organs in the thorax
32
where are the intercoastal muscles
between the ribs
33
what do the intercoastal muscles do
help to connect the bones and are important in moving air into and out of the lungs
34
what is below the lungs
the diaphragm
35
what does the diaphragm do
this domed sheet of muscle and fibrous tissue is also important in moving air into and out of the lungs
36
what is ventilation
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
37
what happens to the diaphragm, intercoastal muscles and rib cage during inhalation
the diaphragm contracts,moving down and flattening
intercoastal muscles contract, moving the rib cage up and out
38
what happens to the volume and air pressure during inhalation
the volume of the thorax increases and air pressure in the thorax falls
39
how does air move into the lungs during inhalation
air pressure in the thorax becomes less than atmospheric pressure, causing air to move into the lungs
40
what happens to the diaphragm, intercoastal muscles and rib cage during exhalation
the diaphragm relaxes, moving up and doming
intercoastal muscles relax, moving the rib cage down and in
41
what happens to the volume and air pressure during exhalation
the volume of the thorax decreases and air pressure in the thorax rises
42
how does air move out of the lungs during exhalation
air pressure in the thorax becomes more than the atmospheric pressure, causing air to move out of the lungs
43
where does gas exchange occur
in the alveoli which is the air sacs
44
what happens during gas exchange in the alveoli
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
45
how is the structure of the alveoli specialised for efficient gas exchange
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
46
what does the composition of inhaled and exhaled air experiment look at
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
47
what indicators could you use to compare inhaled and exhaled air
limewater or hydrogen-carbonate
48
what colour would limewater turn for inhaled air
stays colourless
49
what colour would limewater turn for exhaled air
turns milky white
50
what colour would hydrogen carbonate indicator turn for inhaled air
stays red
51
what colour would hydrogen carbonate indicator turn for exhaled air
turns yellow
52
what experiment could you use to see the effect of exercise on breathing rate
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
53
how would you reach a valid conclusion for the effect of exercise on breathing
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)
54
As well as the depth of each breath, what other affect on breathing does exercise have
during exercise breathing rate increases in response to the increased concentration of carbon dioxide in the blood
55
what happens as a result of breathing rate increasing
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.
56
what happens to breathing rate after exercise if our muscles respire anaerobically
our breathing rate will remain high after exercise to supply the extra oxygen needed to oxidise the lactic acid
57
what is one of the carcinogens in tobacco smoke and what is its affect
tar and it contains chemicals which can alter the DNA and increase the risk of cancer
58
what does carbon monoxide do
irreversably binds to the haemoglobin, forming carboxyhaemoglobin, and so reducing the amount of oxygen transported by the blood
59
what would happen if a pregnant woman smoked
the baby would receive less oxygen and as a result is likely to weigh less at birth which can cause other problems
60
what do goblet cells do
produce mucus which traps dust and pathogens
61
what do the chemicals in tobacco smoke do / effects of smoking
-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
62
carbohydrate food source
bread, potatoes,rice, cereals, fruit
63
function of carbohydrates
fuel for respiration
64
protein food source
meat,eggs, fish, quinoa, quorn
65
function of proteins
growth and repair of cells and tissues
fuel for respiration
66
lipids food source
butter, cooking oil, cream, avocados
67
function of lipids
(thermal and electrical) insulation
fuel for respiration
68
what is the most common substrate
carbohydrate glucose
69
what is glucose stored as in plants
starch
70
what is glucose stored as in animals
glycogen
71
examples of energy being used to keep our body running
heart beating, transport nutrients (active transport) and repair our cells
72
what is energy measured in
kilojoules (kJ) or joules (J)
73
how can you measure the energy content of a food
you can burn a known mass of the food and use the thermal energy released to heat the water
74
describe how you measure the energy content of a food sample
- 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)
75
what is the function of iron in the body
forms the part of haemoglobin which binds to oxygen
76
iron food source
red meat, liver,spinach
77
deficiency disease of iron
Anaemia
78
what is the function of calcium in the body
needed to form bones and teeth
79
calcium food source
milk and dairy products, fish, fresh vegetables
80
deficiency disease of calcium
rickets
81
vitamin A use in the body
making a chemical in the retina and also protects the surface of the eye
82
effect of vitamin A deficiency
night blindness and damaged cornea
83
vitamin A food source
fish liver oil, liver, butter, carrots
84
vitamin C use in the body
needed for cells and tissues to stick together
85
effect of vitamin C deficiency
scurvy
86
vitamin C food source
fresh fruit and vegetables
87
vitamin D use in the body
needed to absorb Calcium and Phosphate ions from food
88
effect of vitamin D deficiency
rickets, caused by weak bones
89
vitamin D food source
dairy products, oily fish
90
why is water needed in the body
water is an essential solvent which is used to transport components of blood and is crucial for temperature regulation (such as sweating)
91
why is fibre needed in the body
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
92
fibre food sources
fruit and vegetables along with grains (wheat, oats etc) are all good sources of fibre as they all contain cellulose
93
what processes happen to food in the alimentary canal
food is ingested, digested, absorbed and egested from this canal for the purpose that the food can be assimilated
94
what is ingestion
taking food in through themouth and swallowing
95
what is digestion
breaking down large insoluble molecules in food into smaller pieces (physical digestion) and smaller, soluble molecules (chemical digestion)
96
what is absorption
movement of small soluble molecules out of the gut and into the blood by diffusion and active transport
97
what is egestion
passing out undigested food through the anus
98
what is assimilation
building larger biological molecules from the small soluble molecules in all cells
99
what two things are called the small intestine together
duodenum and the ileum
100
what two things are called the large intestine together
colon and the anus
101
what is the first structure in the alimentary canal
the mouth
102
where does ingestion take place
the mouth
103
what is mechanical digestion
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
what is chemical digestion
saliva is released into the mouth by the salivary glands which makes the food easier to swallow, and also contains the enzyme amylase
105
what does amylase break starch down into
maltose
106
starch break down in the mouth chemical chain
starch --amylase--> maltose
107
what happens to amylase at the stomach
amylase works best at a neutral pH, so it is denatured when it reaches the stomach and stops working
108
what happens before swallowing
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
what is the flap which blocks food from entering the trachea called
the epiglottis
110
what movement pushed food down the oesophagus
peristalsis
111
how does peristalsis occur in the oesophagus
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
what enzyme do the gastric glands in the stomach release
pepsin and hydrochloric acid
113
what are peptides
shorter chains of amino acids
114
protein breakdown in the stomach chemical chain
protein --pepsin--> peptide
115
what mixes the contents of the stomach
contraction of the stomach causes mixing of its contents, maximising contact between enzymes and food
116
what are pepsin's optimum conditions
an acidic pH
117
how do the conditions of the stomach become acidic
the release of hydrochloric acid by the gastric glands
118
what does the hydrochloric acid do to the food in the stomach
kills many bacteria and fungi which may be oresent in the food eaten
119
what processes occur in the small intestine
digestion and absorption
120
where does digestion happen
the duodenum
121
what is the final site of chemical digestion
the duodenum
122
what does the pancreas do
makes several enzymes and secretes them into the duodenum
123
what enzymes does the pancreas secrete
trypsin, amylase, lipase
124
protein breakdown in the duodenum chemical chain
protein --trypsin--> peptide
125
starch breakdown in the duodenum chemical chain
starch --amylase--> maltose
126
lipid breakdown in the duodenum chemical chain
lipid (fat) --lipase--> glycerol + 3 fatty acids
127
what does the duodenum wall contain
glands which make enzymes and secretes them into the duodenum
128
what enzymes does the duodenum wall secrete
maltase and peptidase
129
maltose breakdown in the duodenum chemical chain
maltose --maltase--> glucose
130
peptide breakdown in the duodenum chemical chain
peptide --peptidase--> amino acids
131
where is bile produced
the liver
132
where is bile stored
the gall bladder
133
where is bile released
the duodenum
134
what are the two functions of bile
- 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
what process stops and what other process begins once the ileum is reached
digestion is over and absorption begins
136
what are the many finger-like projections in the folds of the ileum called
villi
137
what is absorbed through in the ileum
Small soluble molecules
138
how are some of the small soluble molecules absorbed in the ileum
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
how does the ileum increase the rate of diffusion
- 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
what occurs at the colon
the colon is the site for the reabsorption of water
141
where are faeces stores
the rectum
142
where are faeces egested
the anus
143
what is excretion
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
what is the enzyme group that acts upon carbohydrates
carbohydrases
145
what is the enzyme group that acts upon proteins
proteases
146
what is the enzyme group that acts upon lipids
lipases
147
how does temperature affect an enzyme controlled reaction
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
what happens above the optimum temperature
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
what is the pH inside cells
neutral - pH 7
150
what happens to the enzyme if the pH of the environment changes
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
how can you investigate the effect of temperature on enzymes - for example amylase but you can use any enzyme
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
how can you investigate the effect of pH on enzymes
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
what is the blood vessel that transports blood to the heart
pulmonary vein
154
what blood vessel transports blood from the heart
aorta
155
what is the blood vessel that transports blood to the liver
hepatic artery
156
what is the blood vessel that transports blood to the gut
mesentric artery
157
what is the blood vessel that transports blood to the kidneys
renal artery
158
what is the blood vessel that transports blood from the kidneys
renal vein
159
what is the blood vessel that transports blood from the gut
hepatic portal vein
160
what is the blood vessel that transports blood from the liver
hepatic vein
161
what is the blood vessel that transports blood to the heart
vena cava
162
what is the blood vessel that transports blood to the lungs
pulmonary artery
163
what is pulmonary circulation
deoxygenated blood is pumped to the lungs and oxygenated blood returns back to the heart
164
what is systemic circulation
oxygenated blood is pumped to all the other organs of the body and deoxygenated blood returns back to the heart
165
what four chambers is the heart divided into
right atrium
right ventricle
left atrium
left ventricle
166
what is the muscular wall of the atria like
thin muscular walls
167
what is the muscular wall of the ventricles like
thick muscular walls
168
why are the left and right sides of the heart separated by the septum
- 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
why is the left ventricle wall thicker than the wall of the right ventricle
to allow it to pump blood at higher pressures so that the blood can travel around the whole body
170
describe the heart contraction and relaxation process
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
why does heart rate increase during exercise - short
so that more blood can travel to the muscles as they need more glucose and oxygen for aerobic respiration
172
what are changes in heart rate controlled by
nerve impulses from a part of the brain called the medulla
173
why does heart rate increase during exercise - long
- 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
which nerve sends electrical impulses to decrease heart rate at rest
the decelerator nerve
175
what happens to heart rate when we are stressed (angry or afraid)
heart rate increases because it is triggered by the secretion of the hormone adrenaline
176
what type of tissue is blood
a complex tissue
177
what does blood consist of
plasma, platelets and red and white blood cells
178
what is plasma
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
what are red blood cells
small red cells
transport oxygen that is bound to haemoglobin
180
what are platelets
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
what are phagocytes (white blood cells)
larger cells with a multi-lobed nucleus
engulf and digest pathogens (microorganisms which cause disease)
182
what are lymphocytes (white blood cells)
cells with a very large nucleus
make and release antibodies, which bind to and destroy pathogens
183
what do red blood cells contain
haemoglobin
184
how are red blood cells specialised for their job
- 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
what happens if platelets are exposed to oxygen
they release chemicals which start the clotting process
186
what do the chemicals released in the clotting process cause
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
how can clots form in blood vessels
if plaques cause red blood cells to be broken - this can cause heart attacks
188
what do arteries do
arteries carry blood away from the heart - this blood is flowing at high pressure
189
what do veins do
veins return blood into the heart - this blood is flowing at low pressure
190
what do capillaries do
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
structure of an artery
thick outer wall
thick layer of elastic tissue
thick layer of muscular tissue
192
what is the function of the thick outer wall of the artery
can transport blood at high pressure without bursting
193
what is the function of the thick layer of elastic tissue of the artery
allows artery to stretch and recoil to keep blood flowing at high pressure
194
what is the function of the thick layer of muscular tissue of the artery
helps to control flow of blood by widening (dilating) and narrowing (constricting)
195
structure of a vein
fairly thin outer wall
thin layer of muscle and elastic tissue
semilunar valves
196
what is the function of the thin outer wall of the vein
blood is flowing at lower pressure so thick wall is not needed
197
what is the function of the thin layer of muscle and elastic tissue
the wall can contract to keep blood flowing
198
what is the function of the semilunar valves of the vein
prevents blood flowing backwards
199
what is the structure of the capillary
wall is one cell thick
200
what is the function of the wall being one cell thick
short distance for diffusion of substances from blood into tissues
201
what do the coronary arteries do
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
what happens if there are a lot of saturated fats in your diet
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
what are the certain risk factors which make coronary heart disease more likely
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
what is light energy absorbed by in plants
chlorophyll
205
what does photosynthesis occur in
plants as well as some bacteria and protoctista
206
what is the word equation for photosynthesis
carbon dioxide + water --(light energy)--> glucose + oxygen
207
what is the chemical equation for photosynthesis
6CO2 + 6H2O --> C6H12O6 + 6O2
208
what does photosynthesis do
converts light energy into stored chemical energy, which can be used by the organism for respiration and for making other biological molecules
209
what other molecules does glucose make
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
what mineral ions are used by plants to make molecules
Nitrates (NO3^-)
Magnesium (Mg)
Phosphates (PO4^3-)
211
use of nitrates by plants
required to make amino acids (and so proteins) and nucleic acids (DNA and RNA)
212
symptom of nitrate deficiency
stunted growth
213
use of magnesium by plants
required to make chlorophyll
214
symptom of magnesium deficiency
yellow leaves
215
use of phosphates by plants
required to make nucleic acids (RNA and DNA); part of cell membrane
216
symptoms of phosphates deficiency
poor root growth; purple younger leaves
217
what factors affect photosynthesis
carbon dioxide
light intensity
increasing temperature
218
why don't we worry about water affecting the rate of photosynthesis
if the plant is short of water all the cells will be affected and the plant will wilt
219
what is the factor which is in shortest supply called
the limiting factor
220
carbon dioxide effect on rate of photosynthesis
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
light intensity effect on rate of photosynthesis
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
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increasing temperature effect on rate of photosynthesis
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
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how is a leaf specialised for photosynthesis
- 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
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components in the structure of a leaf
cuticle, upper epidermis, pallisade (mesophyll), xylem, phloem, spongey mesophyll, lower epidermis, guard cells, stoma
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how can you test leaves for starch
you can test leaves for starch using iodine solution on a leaf that has had its chlorophyll removed by boiling in ethanol
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describe the experiment of testing a leaf for starch
- 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
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how can a leaf be destarched
by placing it in the dark for 24 hours
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why does a leaf need to be destarched
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
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how can the starch leaf experiment be used to show the conditions needed for photosynthesis
-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
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experiment to investigate how factors affect the rate of photosynthesis
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
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how can you improve the method of investigating the factors affecting the rate of photosynthesis
- 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
