2. STRUCTURE & FUNCTION IN LIVING ORGANISMS Flashcards
1
Q
2.2 cells are separated from their surrounding environment by
A
a cell membrane
2
Q
2.2 within the cell membrane is the
A
cytoplasm
3
Q
2.2 eukaryotic cells have … contained within their cytoplasm
A
organelles
4
Q
2.2 organelles are
A
where specific processes take place within the cell
5
Q
2.2 what is in the cytoplasm of a eukaryotic cell
A
nucleus, mitochondria & ribosomes
6
Q
2.2 plant cells contain the following additional structures
A
cell wall, chloroplasts & a vacuole
7
Q
2.3 function of the nucleus
A
contains genetic material in chromosomes
controls cell division
8
Q
2.3 function of the cytoplasm
A
supports cell structure
site of many chemical reactions
contains water and many solutes
jelly-like substance
9
Q
2.3 function of the cell membrane
A
holds the cell together
controls substances entering and leaving the cell
10
Q
2.3 function of the cell wall
A
gives the cell extra support and defines its shape
11
Q
2.3 function of the mitochondria
A
site of aerobic respiration providing energy for the cell
12
Q
2.3 function of the chloroplasts
A
site of photosynthesis - provides food for plants
chlorophyll pigment absorbs light energy
13
Q
2.3 function of the ribosomes
A
the site of protein synthesis
14
Q
2.3 function of the vacuole
A
contains cell sap
used for storage
helps support the shape of the cell
15
Q
2.4 how many structures does a plant cell have
A
8
16
Q
2.4 how many structures does an animal cell have
A
5
17
Q
2.4 in addition to the structures an animal cell has, a plant cell also has
A
chloroplasts, a (cellulose) cell wall and a vacuole
18
Q
2.4 what does an animal cell have
A
a nucleus, cell membrane, mitochondria, ribosomes and a cytoplasm
19
Q
2.4 what does a plant cell have
A
a nucleus, cell membrane, mitochondria, ribosomes, cytoplasm, chloroplasts, cell wall and a vacuole
20
Q
2.7 the chemical elements present in carbohydrates
A
carbon, hydrogen and oxygen
(C,H,O)
21
Q
2.7 the chemical elements present in proteins
A
carbon, hydrogen, oxygen and nitrogen
(C,H,O,N)
22
Q
2.7 the chemical elements present in lipids (fats&oils)
A
carbon, hydrogen and oxygen
(C,H,O)
23
Q
2.8 starch and glycogen is from
A
simple sugars
24
Q
2.8 protein is from
A
amino acids
25
2.8 lipids are from
fatty acids and glycerol
26
2.8 a monosaccharide is a ...
simple sugar like glucose
27
2.8 a disaccharide is made when
two monosaccharides join together e.g. maltose = glucose & glucose
sucrose = glucose & fructose
28
2.8 a polysaccharide is formed when
lots of monosaccharides join together
29
2.8 polysaccharides starch, glycogen or cellulose are all formed when
lots of glucose molecules join together
30
2.8 most fats (lipids) in the body are made up of
triglycerides
31
2.8 lipids basic unit is
one glycerol molecule chemically bonded to three fatty acid chains
32
2.8 proteins are formed from
long chains of amino acids
33
2.8 when amino acids are joined together
a protein is formed
34
2.9 what is the test for starch?
iodine solution
35
2.9 explain the test for starch
1. place food sample on a spotting tile
2. add a few drops of iodine solution to the sample
3. blue - black colour indicates starch
36
2.9 what is the test for glucose / reducing sugars?
benedicts solution
37
2.9 explain the test for glucose / reducing sugars?
1. place food sample in a boiling tube
2. add benedict’s solution to the sample of food in solution
3. place in a water bath at 80*c for 5 minutes
4. a change from blue to brick red if present
(if green, yellow or orange means less sugar present)
38
2.9 what is the test for protein?
biuret test
39
2.9 explain the test for protein
1. place food sample in a boiling tube
2. add enough biuret solution for colour to be pale blue
3. if protein is present colour will change to mauve / purple
40
2.9 what is the test for lipids?
emulsion test
41
2.9 explain the test for lipids?
1. place food sample in a test tube
2. add small amount of ethanol and shake to dissolve any lipid in the alcohol.
3. add equal volume of water
4. cloudy white colour (emulsion will form) indication presence of lipid
42
2.9 benedicts solution is used to test for
reducing sugars (glucose)
43
2.9 benedicts solution colour change
blue to brick red
44
2.9 how do I remember benedicts solution
christmas sugar
45
2.9 iodine is used to test for
starch
46
2.9 iodine solution colour change
orange to blue-black
47
2.9 how do I remember iodine
bumblebee
48
2.9 biuret is used to test for
protein
49
2.9 biuret solution colour change
(light)blue to pale purple
50
2.9 how do I remember biuret
snowflakes
(et) proTEin biurET
51
2.9 emulsion is used to test for
lipids
52
2.9 emulsion colour change
colourless to a cloudy white emulsion
53
2.9 how do I remember emulsion
snowing
54
2.10 enzymes are biological
catalysts
55
2.10 a catalyst is a ........
chemical which increases the rate of a reaction without being used up itself in the reaction
56
2.10 the theory for understanding how enzymes work is the
lock and key theory
57
2.10 what is the lock and key theory
the substrate and enzyme collide,
the substrate binds to the active site of the enzyme,
(the reaction occurs by an alternative pathway with a lower activation energy)
once the reaction occurs, the products don't fit - so they are released,
the enzyme is free to catalyse the next reaction
58
2.10 the active site has a particular shape which is ... to the shape of the substrates
complementary
59
2.10 because the shape of the active site is complementary to that of the substrates, this means
each enzyme can only catalyse one reaction
60
2.11 as temperature increases the enzyme & substrate have more
kinetic energy
so they move faster and there are more successful collisions
61
2.11 high temperatures and changes of pH cause the shape
to change
62
2.11 when the shape changes we say this is
the protein being denatured
63
2.11 when the active site changes shape it is no longer
complementary to the substrate
64
2.12 practical for investigating effect of temperature on enzymes
mix
10cm3 of 10% starch suspension
+ 5cm3 of 5% amylase
in a boiling tube
heat in water bath
every minute take 1 drop of the mix
add to 1 drop of iodine solution
in spotting tile
when digestion is complete
iodine solution will stay orange
(no starch)
repeat using water baths at different temperatures
65
2.15 definition of diffusion
the random movement of particles from an area of higher concentration to an area of lower concentration
66
2.15 definition of osmosis
the net diffusion of free water molecules from an area of high water concentration to an area of low water concentration across a partially permeable membrane
67
2.15 osmosis in cell:
what is: solution outside cell has same water potential as inside cell - no net movement
isotonic solution
(animal = normal)
(plant = flaccid)
68
2.15 osmosis in cell:
what is: solution outside cell has higher water potential then inside cell - net movement of free water molecules into cell
hypotonic solution
(animal = lysed)
(plant = turgid)
69
2.15 osmosis in cell:
what is: solution outside cell has lower water potential then inside cell - net movement of free water molecules out of cell
hypertonic solution
(animal = shrivelled)
(plant = plasmolysed)
70
2.15 definition of active transport
movement of molecules from an area of low concentration to an area of high concentration using ATP
71
2.16 the four main factors that affect the rate of movement
surface area to volume ratio, distance, temperature and concentration gradient
72
2.16 why is a larger surface area a good thing
it quickens the rate at which substances can move across its surface
73
2.16 example of large surface area
highly folded surface of the small intestine increases its surface area
74
2.16 why is a shorter distance a good thing
the smaller the distance molecules have to travel, the faster the transport will occur
75
2.16 example of short diffusion distance
alveoli walls are one cell thick - rate of diffusion across them is as fast as possible
76
2.16 why is higher temperature a good thing
the higher the temperature, the faster molecules move as they have more energy
77
2.16 how is higher temp a good thing
because there are more collisions against the cell membrane and therefore a faster rate of movement across them
78
2.16 why is a greater difference in a concentration gradient a good thing
the greater the difference in concentration on either side of the membrane, the faster movement across it will occur
79
2.16 how is a greater difference in a concentration gradient a good thing
because the on the side with the higher concentration, more random collisions against the membrane will occur
80
2.17 practical: investigating diffusion
coloured agar is made from indicators
coloured agar is cut into required dimensions
calculate the surface area, SA:V R and volume and record it
cubes placed in boiling tubes of different solutions (same volume of it)
^^^ e.g. dilute hydrochloric acid
measurements taken of time for cube to completely change colour of indicator
can draw a graph of rate of diffusion (rate of colour change) changes with surface area : volume ratio of agar cubes
81
2.17 practical: investigating osmosis
prepare a range of sucrose (sugar) solutions ranging from 0 Mol/dm3 (distilled water) to 1 mol/dm3
set up 6 labelled test tubes with 10cm3 of each of the sucrose solutions
using the knife, cork borer and ruler, cut 6 equally-sized cylinders of potato
blot each one with a paper towel and weigh on the balance
put 1 piece into each concentration of sucrose solution
after 4 hours, remove them, blot with paper towels and reweigh them
82
2.18 process of photosynthesis
energy from sunlight is absorbed by chlorophyll, a green pigment found inside chloroplasts
green plants use this energy to make the carbohydrate glucose from the raw materials carbon dioxide and water
at the same time, oxygen is made and released as a waste product
83
2.19 word and balanced chemical equations for photosynthesis
carbon dioxide + water -> glucose + oxygen
6CO2 + 6H2O -> C6H12O6 + 6O2
84
2.20 how does varying temperature affect the rate of photosynthesis
it affects how much kinetic energy the particles have so affects the speed at which carbon dioxide and water move
more successful collisions
(too high temp can denature enzymes that control the process of photosynthesis)
85
2.20 how does varying light intensity affect the rate of photosynthesis
the intensity of the light available to the plant will affect the amount of energy that it has to carry out photosynthesis
the more light a plant receives, the faster the rate of photosynthesis
86
2.20 how does varying carbon dioxide concentration affect the rate of photosynthesis
carbon dioxide is one of the raw materials required for photosynthesis
this means the more carbon dioxide that is present, the faster the reaction can occur
87
2.21 structure of waxy cuticle
protective layer on top of the leaf prevents water from evaporating
88
2.21 structure of upper epidermis
thin and transparent to allow light to enter palisade mesophyll layer underneath
89
2.21 structure of palisade mesophyll
column shaped cells tightly packed with chloroplasts to absorb more light maximising photosynthesis
90
2.21 structure of spongy mesophyll
internal air spaces which increase surface area to volume ratio for the diffusion of gases (mainly carbon dioxide)
91
2.21 structure of lower epidermis
contains guard cells and stomata
92
2.21 structure of guard cell
absorbs and loses water to open and close stomata to allow
carbon dioxide to diffuse in
oxygen to diffuse out
93
2.21 structure of stomata
where gas exchange takes place
opens during day closes during night
evaporation of water takes place here
found in much greater concentration on underside of leaf to reduce water loss (in most plants)
94
2.21 structure of vascular bundle
contains xylem and phloem to transport substances to and from the leaf
95
2.21 structure of xylem
transports water into leaf for mesophyll cells to use in photosynthesis and for transpiration from stomata
96
2.21 structure of phloem
transports sucrose and amino acids around the plant
97
2.21 what are all the 10 leaf structures
waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis, guard cell, stomata, vascular bundle, xylem and phloem
98
2.21 adaptation of large surface area (leaf)
increases surface area for the diffusion of carbon dioxide and absorption of light for photosynthesis
99
2.21 adaptation of being thin
allows carbon dioxide to diffuse to palisade mesophyll cells quickly
100
2.21 adaptation of chlorophyll
absorbs light energy so that photosynthesis can take place
101
2.21 adaptation of network of veins
allows the transport of water to the cells of the leaf and carbohydrates from the leaf for photosynthesis
(water for photosynthesis)
(carbohydrates - product of photosynthesis)
102
2.21 adaptation of stomata
allows carbon dioxide to diffuse into the leaf and oxygen to diffuse out
103
2.21 adaptation of epidermis being thin and transparent
allows more light to reach the palisade cells
104
2.21 adaptation of thin cuticle made of wax
to protect the leaf without blocking sunlight
105
2.21 adaptation of palisade cell layer at top of leaf
maximises the absorption of light as it will hit chloroplasts in the cells directly
106
2.21 adaptation of spongy layer
air spaces allow carbon dioxide to diffuse through the leaf increasing surface area
107
2.21 adaptation of vascular bundles
thick cell walls of the tissue in the bundles help to support the stem and leaf
108
2.21 specialised leaf for photosynthesis: large surface area and thin
to maximise absorption of sunlight and increases number of stomata so carbon dioxide can diffuse faster
109
2.21 specialised leaf for photosynthesis: upper epidermis
transparent allowing light to penetrate to the mesophyll
110
2.21 specialised leaf for photosynthesis: palisade cells
long thin and tightly packed w large numbers of chloroplasts
main site of photosynthesis
111
2.21 specialised leaf for photosynthesis: stomata
allows gases to diffuse into air spaces of the leaf - short diffusion distance for carbon dioxide
112
2.21 specialised leaf for photosynthesis: xylem transporting water
water that's absorbed in the roots into the leaves so short distance for water to diffuse into cells
113
2.21 specialised leaf for photosynthesis: phloem vessels
phloem vessels transport sugars made in photosynthesis to other parts of plant
114
2.22 plants requires what for growth
mineral ions
115
2.22 chlorophyll requires what to be made
magnesium ions
116
2.22 amino acids require what to be made
(so proteins & nucleic acids - DNA & RNA)
nitrate ions
117
2.23 practical: investigate photosynthesis
take a bundle of shoots of a water plant
submerge them in a beaker of water underneath an upturned funnel
fill a boiling tube with water and place it over the end of the funnel
as oxygen is produced, the bubbles of gas will collect in the boiling tube and displace the water
show that the gas collected is oxygen by relighting a glowing splint
118
2.23 practical: investigating production of starch & photosynthesis&light
de-starch the plant by placing it in a dark cupboard for 24 hours
(this ensures that any starch already present in the leaves will be used up)
partially cover a leaf of the plant with aluminium foil and place the plant in sunlight for a day
remove the covered leaf and test for starch using iodine:
drop the leaf in boiling water
(kills the tissue and breaks down the cell walls)
transfer the leaf into hot ethanol in a boiling tube for 5-10 minutes
(removes the chlorophyll so colour changes from iodine are more clear)
rinse the leaf in cold water
to soften the leaf tissue
spread the leaf out on a white tile and cover it with iodine solution
the entire leaf will turn blue-black as photosynthesis is occurring in all areas of the leaf
proving light is necessary for photosynthesis and production of starch
119
2.23 practical: CORMS evaluation on light & photosynthesis
C - We are changing whether there is light or no light
O - The leaves will be taken from the same plant or same species, age and size of the plant
R - We will repeat the investigation several times to ensure our results are reliable
M1 - We will observe the colour change of the leaf when iodine is applied
M2 - ...after 1 day
S - We will control the temperature of the room
120
2.23 practical: carbon dioxide & photosynthesis
de-starch the plant by placing it in a dark cupboard for 24 hours
following destarching, enclose 1 leaf with a conical flask containing potassium hydroxide
potassium hydroxide will absorb carbon dioxide from the surrounding air
enclose another leaf with a conical flask containing no potassium hydroxide (control experiment)
place the plant in bright light for several hours
test both leaves for starch using iodine solution
drop the leaf in boiling water
transfer the leaf into hot ethanol in a boiling tube for 5-10 minutes
rinse the leaf in cold water
spread the leaf out on a white tile and cover it with iodine solution
the leaf from the conical flask containing potassium hydroxide will remain orange-brown - couldn't photosynthesise due to lack of carbon dioxide
the leaf from the conical flask not containing potassium hydroxide should turn blue-black as it had all necessary requirements for photosynthesis
121
2.23 practical: CORMS evaluation carbondioxide & photosynthesis
C - We are changing whether there is carbon dioxide or no carbon dioxide
O - The leaves will be taken from the same plant or same species, age and size of plant
R - We will repeat the investigation several times to ensure our results are reliable
M1 - We will observe the colour change of the leaf when iodine is applied
M2 - ...after 1 day
S - We will control the temperature of the room and the light intensity
122
2.23 practical: investigating chlorophyll & photosynthesis
drop the leaf in boiling water
This kills the tissue and breaks down the cell walls
transfer the leaf into hot ethanol in a boiling tube for 5-10 minutes
this removes the chlorophyll so colour changes from iodine can be seen more clearly
rinse the leaf in cold water
this is done to soften the leaf tissue after being in ethanol
spread the leaf out on a white tile and cover it with iodine solution
the white areas of the leaf contain no chlorophyll and when the leaf is tested only the areas that contain chlorophyll stain blue-black
the areas that had no chlorophyll remain orange-brown as no photosynthesis is occurring here and so no starch is stored
123
2.23 practical: CORMS evaluation for chlorophyll and photosynthesis
C - We are changing whether there is chlorophyll or no chlorophyll
O - The leaves will be taken from the same plant or same species, age and size of the plant
R - We will repeat the investigation several times to ensure our results are reliable
M1 - We will observe the colour change of the leaf when iodine is applied
M2 - ...after 1 day
S - We will control the temperature of the room and the light intensity
124
2.24 what are the key food groups are for a balanced diet
carbohydrates
proteins
lipids
dietary fibre
vitamins
minerals (mineral ions)
water
125
2.25 carbohydrates
what food source
what function
bread, potatoes, rice, cereals & fruit
fuel for respiration
source of energy
126
2.25 proteins
what food source
what function
meat, eggs, fish, quinoa & quorn
growth and repair of cells and tissues
fuel for respiration
127
2.25 lipids (fats)
what food source
what function
butter, oil, nuts, cream & avocados
store of energy
thermal (and electrical) insulation
fuel for respiration
128
2.25 dietary fibre
what food source
what function
vegetables, whole grains
provides bulk for the intestine to push food through it
129
2.25 vitamins
what food source
what function
fruits and vegetables
needed in small quantities to maintain health
130
2.25 minerals
what food source
what function
fruits and vegetables, meats, dairy products
needed in small quantities to maintain health
131
2.25 water
what food source
what function
water, juice, milk, fruits & vegetables
needed for chemical reactions to take place in cells
132
2.25 calcium
what food source
what function
milk, cheese, eggs
for strong teeth and bones (involved in the clotting of blood)
deficiency leads to osteoporosis later in life
133
2.25 vitamin D
what food source
what function
oily fish, dairy products
(also made naturally by body in sunlight)
helps body to absorb calcium & required for strong bones and teeth
134
2.25 vitamin C
what food source
what function
citrus fruits, strawberries, green vegetables
forms an essential part of collagen protein - makes up skin, hair, gums & bones
deficiency causes scurvy
135
2.25 vitamin A
what food source
what function
meat, liver, dairy, leafygreen vegetables (spinach), eggs
needed to make the pigment in the retina for vision
136
2.25 iron
what food source
what function
red meat, liver, leafygreen vegetables (spinach)
needed to make haemoglobin
^ pigment in redbloodcells that transports oxygen
137
2.26 energy requirements for age
the amount needed in young people increases towards adulthood - energy is needed for growth
children need a higher proportion of protein than adults for growth
energy for adults decrease as they age
138
2.26 energy requirements for activity levels
the more active, the more energy required for movement as muscles are contracting more and respiring faster
139
2.26 energy requirements for pregnancy
requirements increase as energy is needed to support the growth of the developing foetus
extra calcium & iron are needed to help build the bones, teeth and blood of the foetus
140
2.27 function of the mouth
where mechanical digestion takes place
teeth chew food - smaller pieces
amylase enzymes in saliva digest starch into maltose
shaped into bolus so it can be swallowed
141
2.27 function of the oesophagus
connects mouth to the stomach
contractions take place to push bolus down
142
2.27 function of the stomach
food's mechanically digested by churning
protease enzymes chemically digest proteins
hydrochloric acid kills bacteria & optimum pH for protease enzymes to work
143
2.27 function of the small intestine
(duodenum)
food coming out stomach finishes being ^ - digested by enzymes produced here & also secreted from the pancreas
! slightly alkaline pH 8-9
144
2.27 function of the small intestine
(ileum)
where absorption of digested food
- molecules takes place
long & lined with villi - increasing surface
- area where absorption can take place
! slightly alkaline pH 8-9
145
2.27 function of the large intestine
(colon & rectum)
water is absorbed from remaining material in the COLON to produce faeces
faeces is stored in the rectum and removed through the anus
146
2.27 function of the pancreas
produces amylase, protease & lipase
secretes enzymes is an alkaline fluid into the duodenum(LARGEint) to raise pH of fluid coming out of the stomach
147
2.27 what are the 6 structures in the alimentary canal
mouth, oesophagus, stomach, small intestine, large intestine & pancreas
148
2.27 the stages of food breakdown
ingestion - taking in substances,
mechanical digestion - breaking food into smaller pieces
chemical digestion - large, insoluble molecules broken down into small, soluble molecules
absorption - movement of small food molecules and ions through the wall of the intestine into the blood
assimilation - movement of digested food molecules into body where they are used, becoming part of the cells
egestion - passing out undigested or unabsorbed food (as faeces) through the anus
149
2.28 how is food moved through the gut by peristalsis
muscles in the walls of the oesophagus create waves of contractions - forcing the bolus along
once the bolus has reached the stomach, it turns into chyme - continues on to the small intestine
peristalsis is controlled by circular & longitudinal muscles
mucus is produced to continually lubricate the food mass and reduce friction
dietary fibre provides the roughage required for the muscles to push against during peristalsis
150
2.28 what mechanism pushes food through the gut
peristalsis
151
2.29 protein ——>
protein —(pepsin)—>
[peptides] —(trypsin)—> amino acids
152
2.29 (carbohydrates?) starch ——>
(carbohydrates?) starch —(amylase)—> [maltose] —(maltase)—> glucose
153
2.29 lipids ——>
lipids —(lipase)—> glycerol & fatty acids
154
2.29 what enzyme breaks down protein into peptides
what enzyme breaks down peptides amino acids
protease: pepsin
pepsin is made in the stomach
protease: trypsin
trypsin is made in the pancreas & small intestine
155
2.29 what enzyme breaks down carbohydrates into maltose
what enzyme breaks down maltose into glucose
carbohydrase: amylase
amylase is made in pancreas and salivary glands
carbohydrase: maltase
maltase is made in pancreas
156
2.29 what enzyme breaks down lipids into fatty acids and glycerol
lipase: lipase enzymes
lipase enzymes are produced in the pancreas
157
2.30 where is bile produced
in the liver
158
2.30 where is bile stored
in the gall bladder
159
2.31 what does bile do to stomach acid
it neutralises the hydrochloric stomach acid
160
2.31 what does bile do to lipids
it emulsifying lipids
161
2.31 how does bile neutralise stomach acid
the alkaline properties in it allow it to neutralise the hydrochloric acid
the neutralisation is essential as enzymes in small intestine have higher optimum pH
162
2.31 how does bile emulsify lipids
it breaks apart large drops of fat into smaller ones (increasing their surface area)
163
2.32 how is the small intestine adapted for absorption
it is very long and has a highly folded surface with millions of villi
which increase the surface area allowing absorption to take place faster and more efficiently
peristalsis helps by mixing food and enzymes and keeping things moving
164
2.32 how is the structure of a villus adapted for absorption
a large surface area:
microvilli on the surface
short diffusion distance:
one cell thick walls
steep concentration gradient:
- surrounded by a network of blood
capillaries - transport
glucose&amino acids away
- a lacteal to transport fatty acids and glycerol away
165
2.33B practical: energy content of a food sample practical:
measure 25cm3 of water
pour into boiling tube
record starting temp
food is lit over bunsen burner
hold food under boiling tube to heat it
(if food stops burning relight it)
relight until food no longer burns
measure finishing temp of water
calculate the temp change
166
2.34 how does the process of respiration produce ATP
energy is released from glucose either in the presence of oxygen (aerobic) or no oxygen (anaerobic)
resulting in the production of carbon dioxide and water as waste products
energy is transferred in the form of ATP
167
2.35 what does ATP provide for cells
ATP provides energy for cells
(muscle contractions & keeping warm - painting a constant temperature)
168
2.36 differences between aerobic & anaerobic respiration with oxygen
aerobic needs oxygen
anaerobic doesn't need oxygen
169
2.36 differences between aerobic & anaerobic respiration with the breakdown of glucose
breakdown is complete in aerobic
breakdown is incomplete in anaerobic
170
2.36 differences between aerobic & anaerobic respiration with the products
aerobic = carbon dioxide & water
anaerobic =
anima cells: lactic acid
yeast: carbon dioxide & ethanol
171
2.36 differences between aerobic & anaerobic respiration with the energy released
aerobic releases a lot of energy
anaerobic releases a little
172
2.37 word equation for aerobic respiration
glucose + oxygen → carbon dioxide + water
173
2.37 the balanced chemical symbol equation for aerobic respiration
C6H12O6 + 6O2 → 6CO2 + 6H20
174
2.38 the word equation for anaerobic respiration in animals
glucose ---> lactic acid
175
2.38 the word equation for anaerobic respiration in plants
glucose ---> ethanol + carbon dioxide
176
2.39 practical: evolution of carbon dioxide from respiring seeds
measure out 10 cm3 of hydrogencarbonate indicator into 3 boiling tubes
put in a layer of cotton wool
place 10 germinating seeds in tube A
place 10 boiled/dead seeds in tube B
place 10 glass beads in tubeC
seal each tube with a rubber bung
after 3 hours, observe the colour of the indicator
high CO2 = yellow
atmospheric CO2 = orange
low CO2 = purple
177
2.39 practical: demonstrating the production of heat from respiring seeds
flask A with the dead seeds
flask B with the germinating seeds
make sure the cotton wool is plugging the top of each flask
hold the thermometer in place with the cotton wool
invert the flask
record the initial temperature
after 4 days, record the final temperature
178
2.39 practical: analysis
the thermometer in the flask with the germinating seeds (Flask B) should show an increase in temperature
- the seeds in flask B are respiring and producing heat energy in the process
flask A should remain at room temperature
the seeds in flask A are not respiring because they are dead, so the temperature remains the same
this shows that respiration is an exothermic reaction
179
2.39 practical: CORMS evaluation evolution of carbon dioxide
change - we will change the content of the boiling tube (germinating seeds, dead seeds or glass beads)
organisms - the seeds used should all be of the same age, size and species
repeat - we will repeat the investigation several times to ensure our results are reliable
measurement 1 - we will observe the change in the hydrogen carbonate indicator
measurement 2 - ...after 3 hours
same - we will control the volume of hydrogen carbonate indicator, the number of seeds/beads, the temperature of the environment
180
2.39 practical: CORMS evaluation evolution of heat
change - we will change the content of the flasks (germinating seeds or dead seeds)
organisms - the seeds used should all be of the same age, size and species
repeat - repeat the investigation several times to ensure our results are reliable
measurement 1 - change in the temperature on the thermometer
measurement 2 - ...after 4 days
same - control the number of seeds, the starting temperature of the flasks, the material and size of the flasks
181
2.49 smoking can cause ... and several types of caner including ...
coronary heart disease and lung cancer
182
2.49 what does nicotine do
it narrows blood vessels - increased blood pressure
increased heart rate
183
2.49 what does carbon monoxide do
binds irreversibly to haemoglobin
breathing frequency has to increase
increases risk of coronary heart disease & strokes
184
2.49 emphysema does what
makes the alveoli less elastic & cannot stretch
the breakdown of alveoli reduces the surface area for gas exchange
185
2.49 smoking increases the risk of cancer which is
the rapid uncontrolled cell growth
186
2.49 tobacco smoke contains ______ ________ which permanently binds to the haemoglobin forming __________________ reducing the amount of oxygen being transported by the blood
carbon monoxide
carboxyhaemoglobim
187
2.49 in healthy lungs the linings of the trachea and bronchi are
specialised to prevent dirt and bacteria entering the lungs
188
2.49 the cilia of the lining cells move transporting the mucus
up the airways where it is then swallowed
189
2.49 chemicals in tobacco smoke destroy _____ reducing their number, at the same time mucus production will increase. the mucus cannot be moved out of the airways quickly so it ______ __ causing _______ _____ and increases the risk of infection
cilia
builds up
smokers cough
190
2.49 __________ is a disease resulting from the build up of in refuted mucus in the bronchi and bronchioles
bronchitis
191
2.49 smoke can also reach the alveoli damaging them: the alveoli walls break down in places and fuse together forming larger irregular air spaces this ___ the surface area for gas exchange so ____ oxygen diffuses into the blood, this disease is called _________ and kills around 20k people in Britain per year
decreases
less
emphysema
192
2.49 chemicals in cigarettes include:
tar - a carcinogen (a substance that causes cancer)
nicotine - an addictive substance which also narrows blood vessels
carbon monoxide - reduces the oxygen-carrying capacity of the blood
193
2.50 practical: the effect of expertise on breathing method
work out student A's breathing rate at rest
count their number breaths for 15 seconds and multiply by 4
repeat to calculate an average
student A should then exercise for a set time (at least 4 minutes)
count the breaths taken in 15 seconds and multiply by 4 to obtain the breathing rate per minute
compare the result to the breathing rate at rest in order to work out the change in breathing rate as a result of exercise
repeat this last step every minute after exercise for 5 minutes
repeat the process for student B
finally, repeat the whole investigation for each student after a period of rest
194
2.50 practical: the effect of exercise on breathing results
frequency of breathing increases when exercising
this is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand
if they cannot meet the energy demand they will also respire anaerobically, producing lactic acid
195
2.50 practical: the effect of exercise on breathing analysis
after exercise has finished, the breathing rate remained elevated for a period of time
this is because the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions
it can only be removed by combining it with oxygen - this is known as ‘repaying the oxygen debt’
this can be tested by seeing how long it takes after exercise for the breathing rate to return to normal
the longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid
196
2.50 practical: what might an unfit individual have
higher breathing rate while resting
more rapid increase in breathing rate during exercise
longer recovery period for their breathing rate to return back to a normal resting rate
197
2.50 practical: how do you control all variables
ensure students are similar size, general fitness, age, gender and provide each with the same meal before exercise
198
2.50 practical: CORMS evaluation
change - We will change whether the student has exercised or not
organisms - The students should be of the same age, gender, size and general fitness
repeat - We will repeat the investigation several times to ensure our results are reliable
measurement 1 - We will measure the change in breathing rate
measurement 2 - ...immediately after exercise and each minute for the subsequent 5 minutes
same - We will control the type of exercise carried out, the temperature of the environment, the food intake of the students prior to the investigation
199
2.50 practical: exercise causes the frequency
exercise causes the frequency of breathing to increase in order to provide more oxygen for respiration and to pay off any subsequent oxygen debt
200
2.50 practical: apparatus needed for the effect of exercise
a stop watch
2 students
201
2.55B plants take in water from the soil through
their root hairs
202
2.55B root hairs are thinwalled
for a short distance
203
2.55B root hairs have hair-like extensions to
increase the surface area
204
2.55B the function of a root hair is to
absorb water and minerals from the soil
205
2.55B mineral ions are
actively transported into the root hair cells
206
2.55B water will enter the root hair cell by
osmosis
207
2.55B the soil water has a ... concentration of water molecules
higher
208
2.55B osmosis is
the net diffusion of water molecules from an area of high water concentration to an area of low water concentration across a partially permeable membrane
209
2.56B the loss of water vapour from the leaves is called
transpiration
210
2.56B examiners definition of transpiration
the evaporation of water from the surface of a plant
211
2.57B how does temperature affect the rate of transpiration
water will evaporate quickly as the water molecules have more kinetic energy
212
2.57B how does humidity affect the rate of transpiration
humid air - water vapour = smaller conc gradient so transpiration slows down
213
2.57B how does wind speed affect the rate of transpiration
moving air - water vapour blown away from leaf - speeds up transpiration
214
2.57B transpiration .. as wind speed ..
transpiration increases as wind speed increases
215
2.57B transpiration .. as humidity ..
transpiration increases as humidity decreases
216
2.57B transpiration .. as temperature ..
transpiration increase as temp increases
217
2.57B light intensity does NOT affect
evaporation
218
2.57B how does light intensity affect the rate of transpiration
in daylight stomata leaves are open to supply CO2 for photosynthesis
allows more water to diffuse out leaves into atmosphere
219
2.58B practical: how to set up a potometer
set up underwater
cut the stem
shoot stem in bung
grease joint w jelly (no air entry/water loss)
bung in potometer
tap closed full of water
lift potometer out of water
leave end of capillary tube out of water until air bubble forms & then put in beaker of water
measure rate as distance bubble travelled in 5 mins
220
2.58B practical: a potometer is to measure
measure the rate of water uptake from a leafy shoot
221
2.58B practical: we can use potometer to collect readings in normal air or windy conditions by
using a hairdryer on cold
222
2.58B practical: we can use potometer to collect readings in temperature
increases and decreases
223
2.58B practical: we can use potometer to collect readings in increased humidity by
using a clear plastic bag
224
2.58B practical: we can use potometer to collect readings by changing the l & d
lightness and darkness
225
2.58B practical: changing the environmental factors stimulates
all the different conditions which affect the rate of transpiration
226
2.71 what are the excretory products of the lungs
carbon dioxide
(via blood plasma)
227
2.71 what are the excretory products of the kidneys
urea
228
2.71 what are the excretory products of the skin
urea
229
2.71 water is lost from the body in the following ways:
via the lungs during exhalation (breathing out)
lost from the skin as sweat (along side mineral ions and urea)
230
2.72B what does the kidney do
it filters the blood and removes any excess materials and passes them to the bladder to be excreted
231
2.72B the kidney contains millions of tiny structures called
nephrons
232
2.72B nephrons are structures which
filter the blood
233
2.72B what are the 3 main regions of the kidney
cortex, medulla and renal pelvis
234
2.74B what are the 3 stages that occur in the nephron
ultrafiltration, selective reabsorption and water reabsorption
235
2.74B the main sections in a nephron
bowman's capsule
proximal convoluted tubule
loop of henle
distal convoluted tubule
collecting duct
236
2.74B surrounding the tubule is a network of
capillaries with a knotted section which sits inside the bowman's capsule
237
2.74B where does the glomerulus sit
inside the bowmans capsule
238
2.74B what shape is the bowmans capsule
cup shaped
239
2.74B the glomerulus is a knot of
capillaries
240
2.74B where is glucose reabsorbed
in the proximal first convoluted tubule
241
2.74B the gates that facilitate the active transport of glucose are
only found in the proximal convoluted tubule
242
2.74B the cells lining in the PCT have many mitochondria to
provide ATP (energy) for active transport
243
2.74B the cells lining in the PCT have a folded membrane
to increase surface area
244
2.74B where is water reabsorbed
loop of henle and collecting duct
245
2.74B where are salts reabsorbed
loop of henle
246
2.75B step1. the diameter of the efferent arteriole at the exit of the glomerulus is
smaller than the diameter of the afferent arteriole at the entrance causing a build up of pressure
247
2.75B step1. the build up of pressure in the capillaries forms the
glomerulus
248
2.75B step2. the pressure causes the smaller molecules being carried in the blood to be forced out of the capillaries and into
the bowman’s capsule
where they form the glomerular filtrate
249
2.75B step2. small molecules like urea, glucose, amino acids, water and salts are forced
out the glomerulus into the bowmans capsule
250
2.75B step3. larger molecules like proteins or red blood cells are
too big to fit across the capillary wall so they stay in the blood
251
2.75B where is water reabsorbed
loop of henle & collecting duct
252
2.75B where are salts reabsorbed
loop of henle
253
2.75B where is glucose reabsorbed
proximal first convoluted
254
2.75B where is urea reabsorbed
it is NOT reabsorbed
255
2.75B what small molecules are pushed through
urea, glucose, amino acids, water and salts
256
2.75B what large molecules are too big to go through so stay in the blood
proteins and red blood cells
257
2.75B what makes up the glomerular filtrate
urea, glucose, amino acids, water and salts
258
2.77B after the glomerular filtrate enters the bowman’s capsule what's the first thing to be reabsorbed
glucose is the first substance to be reabsorbed at the proximal (first) convoluted tubule
259
2.77B selective reabsorption takes place by
active transport
260
2.77B the cells lining in the PCT have a folded membrane for
an increased surface area
261
2.77B the cells lining in the PCT have many mitochondria to
provide ATP (energy) for active transport
262
2.77B reabsorption of glucose cannot take place anywhere else in the nephron as
the gates that facilitate the active transport of glucose are only found in the proximal convoluted tubule
263
2.79B urine contains
water, urea and ions
264
2.79B if someone is diabetic their urine may contain
glucose
265
2.79B urine produced by the kidneys contains a mixture of
urea
excess mineral ions
excess water
266
2.79B small quantities of urine are usually darker yellow / orange in colour because
it contains little water and so the urea is more concentrated
267
2.79B large quantities of urine are usually pale yellow in colour
because it contains a lot of water and so the urea is less concentrated
268
2.77B where does selective reabsorption of glucose occur
in the proximal convoluted tubule
269
2.79B what produces urine
the kidneys
270
2.77B what's special about the reabsorption of glucose
its selectively reabsorped
