year 10 eoy exam Flashcards
1
Q
what are the characteristics of living organisms?
A
MRS H GREN
Movement
Respiration
Sensitivity (they respond to their surroundings)
Homeostasis (maintaining internal conditions)
Growth
Reproduction
Exretion
Nutrition
2
Q
are plants multicellular?
A
yes
3
Q
what are the cell walls of plants made of?
A
cellulose
4
Q
what do plants store carbohydrates as?
A
starch or sucrose
5
Q
what are some examples of plants?
A
maize, peas, beans
6
Q
are animals multicellular?
A
yes
7
Q
can animals photosynthesise?
A
no
8
Q
what do they store carbohydrates as?
A
usually glycogen
9
Q
do animals have nervous coordination?
A
yes, and they an move from one place to another
10
Q
what are some examples of animals?
A
humans, tigers, dogs, houseflies, spiders
11
Q
are fungi able to photosynthesise?
A
no
12
Q
what are fungi bodies normally organised into?
A
a mycelium made from thread like structures called hyphae which contain many nuclei
13
Q
are fungi multicellular?
A
some are, some aren’t
14
Q
what are the cell walls of fungi made of?
A
chitin
15
Q
how do fungi feed?
A
using saprotrophic nutrition
16
Q
what is saprotrophic nutrition?
A
digestive enzymes are secreted outside of the cell onto the food, which is then broken down into small soluble molecules and absorbed by the decomposer
17
Q
are protoctists multicellular?
A
not usually
18
Q
what are some examples of protoctists?
A
animal-like: amoeba
plant-like: chlorella, plasmodium
19
Q
are bacteria multicellular?
A
no
20
Q
are bacteria eukaryotic?
A
no, they’re prokaryotic
21
Q
what do bacteria have instead of a nucleus?
A
a circular chromosome of DNA
22
Q
can bacteria photosynthesise?
A
some can, but most feed off of dead organsisms
23
Q
what do bacteria cells contain?
A
a cell wall, a cell membrane, cytoplasm, plasmids, and a circular chromosome of DNA
24
Q
what might be pathogens?
A
fungi, bacteria, protoctists, viruses
25
are viruses living?
no
26
how big are viruses?
smaller than bacteria
27
are viruses parasitic?
yes
28
what is the structure of a virus?
a protein coat and ne type of nucleic acid (either RNA or DNA)
29
what are some examples of viruses?
tobacco mosaic virus (causes discolouring of tobacco pant leaves by preventing formation of chloroplasts)
influenza virus (causes the flu)
HIV (causes AIDS)
30
what kind of organisms do viruses infect?
every type of living organisms
31
what is a pathogen?
a pathogen are microorganisms which cause infectious disease. they harm the host by releasing toxins or damaging cells
all viruses are pathogens, fungi, bacteria and protoctists can be pathogenic (but not all of them are)
32
what is the function of the nucleus?
controls the activity of the cell (by making proteins)
contains the chromosomes - strands of DNA which carry the genes
33
what is the function of the cytoplasm?
it is where reactions occur
34
what is the function of the cell membrane?
controls what substances go in and out of the cell (it is semi-permeable)
35
what is the function of the cell wall?
keeps the cell in a fixed shape and prevents the cell bursting
36
what is the function of the mitochondria?
site of respiration, produces ATP
37
what is the role of the chloroplasts?
light energy absorption, site of photosynthesis, produces chemical molecules for the plant/cell
38
what is the function of the ribosomes?
site of protein synthesis (from amino acids)
39
what is the function of the vacuole?
stores dissolved sugars, mineral ions, and other substances
40
what are the similarities and differences of plant and animal cells?
both have: nucleus, mitochondria, cell membrane, cytoplasm, ribosomes
just plant: cell wall (cellulose), chloroplasts, vacuole
just animal: n/a
41
what are the chemical elements present in carbohydrates?
CHO
42
what are the chemical elements present in proteins?
CHON
43
what are the chemical elements present in lipids?
CHO
44
what is the smallest unit of carbohydrates?
glucose (monosaccharide)
45
what does glucose make up?
starch (polysaccharide)
46
what is the smallest unit of proteins?
amino acids
47
what is the smallest unit of lipids?
fatty acids and glycerol
48
how do you test for glucose?
1. place a small sample (approx. 2cm^3) of food in a test tube
2. then add 1cm^3 of Benedict's solution, or enough for it to appear blue
3. then heat in an 85 degree celcius water bath for 5 minutes
4. if the mixture turns from blue to green/yellow/orange/brick red then sugar is present
49
how do you test for starch?
1. take a small sample of food and place it in a well on a spotting tile
2. add 10 drops of iodine solution/a roughly equal amount of iodine to food
3. if starch is present, the iodine changes from orange to black/blue
50
how do you test for proteins?
1. place a small food sample in a test tube
2. add a roughly equal amount of Biuret solution or enough for the pale blue colour to be seen
3. if the mixture turns from blue to mauve/purple, proteins are present
51
how do you test for lipids (fats)?
1. place a small food sample in a test tube
2. add roughly equal amount of ethanol and mix well
3. add roughly equal amount of water (1:1:1) and mix well again
4. if the mixture turns milky, fat is present
52
how do enzymes work as biological catalysts in metabolic reactions?
they lower the activation energy needed for the reaction to occur. they speed up reactions, by the lock and key theory; the enzyme's active site will fit the substrate perfectly and make the reaction happen
53
how does temperature change effect enzymes?
as temperature increases, the enzymes and the substrate get more kinetic energy, so more enzyme-substrate complexes are formed as thee are more collisions. as the temperature increases past the optimum temperature, enzymes denature, as they have too much kinetic energy so the enzyme's active site denatures, so the substrate can no longer fit, so there are less/no enzyme substrates formed
54
how would you test to see how temperature effects enzyme activity?
1. place single drops of iodine solution in rows on the spotting tiles
2. label a test tube with the temperature to be tested (eg. 10 degrees celcius)
3. use cold water from the tap and hot water from the kettle to prepare a water bath at that temperature, and keep it at that temperature for the test using a thermometer
4. use a syringe to place 2cm^3 of amylase into the test tube, then place it in the water bath for 5 minutes
5. use another syringe to add 2cm^3of starch solution to the amylase solution (leaving the test tube in the water bath) start the stop watch and mix using the pipette
6. after 30 seconds, use the pipette to squirt one drop of iodine solution into the first drop of iodine, the squirt the rest of the pipette back in the test tube. the iodine solution should turn blue/black
7. after another 30 seconds, drop another drop of the solution into the next iodine drop
8. repeat step 7 until the iodine stays orange
9. count how many iodine drops you used, each equals 30 seconds of reaction time
10. repeat 1-9 for each temperature (eg 20, 30, 40, 50, 60)
11. repeat each temperature 3 times and work out a mean
55
what is the definition of diffusion?
the random movement of particles from an area of high concentration to an area of low concentration
56
what is the definition of osmosis?
the net diffusion of free water molecules from an area of high water potential to an area of low water potential across a partially permeable membrane
57
what is the definition of active transport?
the movement of molecules from an area of low concentration to an area of high concentration using ATP
58
what factors effect the rate of diffusion and osmosis?
temperature, surface area to volume ratio, distance, concentration gradient
59
how does temperature affect the rate of diffusion/osmosis?
at higher temperatures, molecules have more kinetic energy, so they move faster, so diffusion (/osmosis) happens faster
60
how does distance affect the rate of diffusion/osmosis?
shorter distance means the molecules can get there quicker, so the diffusion is faster with smaller distances
61
how does the concentration gradient affect diffusion/osmosis?
if there is a very big difference in concentration, molecules will diffuse quickly, if the difference is small, they diffuse slower
62
how does surface area to volume ratio affect diffusion/osmosis?
surface area increases the rate of diffusion because there are more opportunities for the molecules to move in. if you have many small things instead of one big thing, the sa:v increases so the rate increases too
63
write the method to investigate osmosis in a living organism?
1. use a cork borer to cut 5 cylinders out of a potato
2. use a knife to cut the cylinders to all the same length (about 3cm)
3. accurately measure the potatoes then accurately weigh them
4. measure out 75ml of 1.0M salt solution and put it into a boiling tube and label it
5. repeat step 4 for 0.0M, 0.25M, 0.50M, 0.75M salt solutions
6. draw out a table of results
7. add one potato cylinder to each boiling tube and make sure that you know the measurement of each potato
8. leave each potato in the boiling tube for at least 15 minutes
9. take the potatoes out of the boiling tube and pat dry with a paper towel
10. measure the mass of each potato cylinder and record it in the table and calculate the percentage change for each potato cylinder
11. plot a graph of change in mass /g (y) against the concentration of salt solution /M, then find the x-intercept to find the isotonic point of the potato
64
photosynthesis converts what into what?
it converts light energy to chemical energy
65
what is the word equation for photosynthesis?
water + carbon dioxide -light energy-> oxygen + glucose
66
what is the balanced chemical equation for photosynthesis?
6H(2)O + 6CO(2) --> 6O(2) + C(6)H(12)O(6)
67
what factors affect the rate of photosynthesis?
1. carbon dioxide concentration
2. light intensity
3. temperature
68
how does varying carbon dioxide concentration affect photosynthesis?
a higher concentration of carbon dioxide increases the rate of photosynthesis because there are more molecules for the enzymes to collide with
at a certain point, increasing the concentration doesn't change anything, as it is no longer the limiting factor
69
how does varying light intensity affect the rate of photosynthesis?
increasing the light intensity increases the rate of photosynthesis because there is more energy for the reaction to occur
at a certain point increasing the light intensity doesn't change anything because something else has become the limiting factor
70
how does varying the temperature affect the rate of photosynthesis?
increasing temperature increases the rate of reaction as the enzymes and substrates have more kinetic energy so they collide more often so there are more successful enzyme-substrate complexes formed. this is until the temperature increases past the optimum, where the rate slows down as the enzymes have too much kinetic energy and denature as their active site changes shape so the substrate no longer fits, so there are less/no enzyme-substrate complexes form, so the rate of reaction does not increase
71
describe the structure of a leaf and explain how it is adapted for photosynthesis
- the waxy cuticle prevents water loss via evaporation and osmosis through the leaf
- the transparent upper epidermis allows the light to reach the palisade mesophyll layer
- the palisade mesophyll layer cells are thin, long, and tightly packed together and have lots of chloroplasts to maximise the amount of light energy absorbed for photosynthesis
- the spongy mesophyll layer has air spaces for carbon dioxide diffusion
- the xylem transports the water into the leaf so there is a short diffusion distance
- the phloem allows the sugars produced in photosynthesis to be transported to other respiring cells
- the stomata and guard cells control the amount of water transpiration and the amount of carbon dioxide diffusion into the cell depending on the amount of light
72
what do plants use magnesium ions for?
they are needed to make chloroplasts
73
what do plants use nitrate ions for?
it is needed to make amino acids, for cell growth
74
what do plants need phosphate ions for?
it is needed to make DNA
75
describe the method to investigate how light intensity affects photosynthesis
1. place the beaker of pondweed 10cm away from the light source
2. count the number of bubbles produced in one minute (using a stopwatch
3. repeat twice more and record the mean
4. repeat 1-3 for 4 more distances, eg. 15cm, 20cm, 25cm, 30cm
5. record the results in a table
76
describe the method to investigate wether carbon dioxide is needed for photosynthesis
1. de-starch the plant by putting it in a dark cupboard for 24 hours
2. put a conical flask containing potassium hydroxide around one leaf, this will absorb the carbon dioxide in the air
3. put an empty conical flask around another leaf as a control test
4. place the plant in a bright place
5. test both leaves for starch using iodine solution (drop it in boiling water, place it in hot ethanol for 5-10mins, spread on a white tile and drop iodine solution over it)
77
describe the method to investigate how chlorophyll affects photosynthesis
1. use a variegated leaf
2. put the leaf in boiling water for 30 seconds to kill the tissue and break down cell wall
3. put the leaf in a boiling tube of hot ethanol for 5-10mins to remove the chlorophyll so the colour can be seen more easily
4. rinse the leaf under cold water to soften it
5. spread it out on a white tile and use iodine to test for starch, the white parts should stay orange and the green parts will turn blue/black
78
what should a balanced diet contain?
appropriate proportions of carbohydrates, protein, lipids, vitamins, minerals, water, and dietary fibre
79
what are the functions of carbohydrates?
direct source of energy, fuel for respiration
80
what is the function of dietary fibre?
provides bulk for intestines to push food through it, decreases the risk of bowel cancer and constipation
81
what is the function of lipids?
- storing and providing energy
- thermal and electrical insulation
- fuel for respiration
82
what is the function of proteins?
- helps repair and build tissues
- fuel for respiration
83
what is the function of vitamin a?
- making a chemical in the retina and keeps it healthy
- protects the surface of the eye
- prevents night blindness
84
what is the function of vitamin c?
- prevents scurvy
- needed for cells and tissues to stick together
85
what is the function of vitamin d?
- needed to absorb calcium and phosphate ions from food
- prevents rickets
86
what is the function of iron?
forms part of haemoglobin, prevents anaemia
87
what is the function of calcium?
needed to form bones and teeth
prevents rickets and osteoporosis
88
what are some sources of carbohydrates?
bread, potatoes, rice, cereals, fruit
89
what are some sources of dietary fibre?
fruit, vegetables, grains
90
what are some sources of lipids?
butter, cooking oil, avocados, cream
91
what are some sources of proteins?
meat, eggs, fish, quinoa, quorn
92
what are some sources of vitamin a?
fish oils, liver, butter, carrots
93
what are some sources of vitamin c?
fresh fruits and vegetables
94
what are some sources of vitamin d?
dairy products, oily fish
95
what are some sources of iron?
red meat, liver, spinach
96
what are some sources of calcium?
milk and dairy products, fresh fruit, fish
97
what is the function of water?
it is an essential solvent, transports components of blood, is essential for temperature regulation
98
what are some sources of water?
water, cucumber, lettuce
99
what is the function of the mouth in digestion?
mechanical digestion, increasing the surface area of food (by making it into bolus), salivary amylase breaks down starch into maltose, saliva makes food easier to swallow
100
what is the function of the oesophagus in digestion?
mechanical digestion; peristalsis occurs to push bolus down towards the stomach
101
what is the function of the stomach in digestion?
mechanical digestion (muscle churning), chemical digestion (pepsin), stomach acid to lower pH for optimum enzyme activity, sterilises food
102
what is the function of the duodenum in digestion?
chemical digestion- enzymes break down food
103
what is the function of the ileum in digestion?
chemical digestion- enzymes break down food
villi and micro villi to absorb nutrients
104
what is the function of the colon in digestion?
reabsorbing water to form faeces
105
what is the function of the rectum in digestion?
egestion
106
what is the function of the pancreas in digestion?
secretes enzymes into stomach and small intestine for chemical digestion
107
how does food move through the oesophagus?
through peristalsis
108
what enzymes are there and what kind of enzyme reactions are there in the mouth?
salivary amylase
starch --> maltose
109
what enzymes are there and what kind of enzyme reactions are there in the stomach?
pepsin (protease)
proteins --> peptides
110
what enzymes are produced in the pancreas?
pancreatic amylase, trypsin (protease), pancreatic lipase
111
what enzymes are there and what kind of enzyme reactions are there in the duodenum?
pancreatic amylase, trypsin (protease), pancreatic lipase
starch --> maltose
peptides --> amino acids
lipids --> fatty acids + glycerol
in the walls (gets secreted out):
maltase
maltose --> glucose
112
what enzymes are there and what kind of enzyme reactions are there in the ileum?
(in the walls and gets secreted out)
maltase
maltose --> glucose
113
where is bile produced?
liver
114
where is bile stored?
gall bladder
115
what is the function of bile?
emulsifies lipids (increases surface area), neutralises stomach acid
116
what does stomach acid contain?
hydrochloric acid and pepsin
117
how is the small intestine adapted for absorption?
thin cell wall - decreases diffusion distance for soluble molecules
large surface area to volume ratio - villi increases surface area for diffusion
large network of capillaries - maintain the concentration gradient
118
what is the method to investigate the energy content of a food sample?
1. add 25cm3 of water to a boiling tube, measured with a measuring cylinder, support the boiling tube in a clamp stand
2. weigh the food sample and place it on a mounted needle
3. place the thermometer in the boiling tube and wait for 5 minutes
4. record the initial temperature
5. hold the food sample over a bunsen burner until it catches fire
6. place the food under the test tube until it appears to not be alight
7. repeat step 5 and 6 until the food cannot catch fire anymore
8. stir the thermometer in the boining tube for 10 seconds then record the final temperature
119
what does ATP provide for cells?
energy
120
what is the difference between aerobic and anaerobic?
aerobic: with oxygen
anaerobic: without oxygen
aerobic produces more energy
121
what is the word equation for aerobic respiration?
oxygen + glucose --> carbon dioxide + water (+ATP)
122
what is the balanced chemical equation for aerobic respiration?
6O2 + C6H12O6 -->6CO2 + 6H2O
123
what is the anaerobic word equation in animals?
glucose --> lactic acid
124
what is the anaerobic word equation in plants and fungi?
glucose --> ethanol + carbon dioxide
125
what is the method to investigate the evolution of carbon dioxide in living organisms?
1. pour some sodium hydroxide solution into the first conical flask. this is connected to the pipe that allows the inflow of air and removes the carbon dioxide from the air
2. pour some hydrogen carbonate indicator in the second flask. this is connected to the first flask with a delivery tube
3. place the respiring seeds in the third conical flask on some moist cotton. this is connected to the second conical flask
4. pour some hydrogen carbonate indicator in the fourth flask, which is connected to the pipe to allow the outflow of air
5. observe the colour of the hydrogen carbonate indicator
126
what colour does hydrogen carbonate indicator go in carbon?
yellow
127
what is the method to investigate the evolution of heat in living organisms?
1. set up two thermoflasks
2. place the respiring seeds with cotton wool in one of the thermoflasks
3. place the boiled seeds with moist cotton wool in the other thermoflask
4. use a thermometer to measure and record the initial temperature
5. after a certain number of days, measure and record the final temperature and work out the temperature difference
128
what is the effect of smoking on the air passages?
- tar in cigarettes destroys cilia (which gets rid of dust and microbes trapped in mucus) so it causes a build up of mucus, and increased risk of bronchitis
- tar in cigs contains carcinogens which increases risk of lung cancer
129
what effect does smoking have on alveoli?
tar in cigs breaks down alveoli walls and makes them merge together, so it increases the surface area : volume
insufficient gas exchange will increase the risk of emphysema - shortness of breath due to insufficient oxygen transport in blood
130
what effect does smoking have on the circulatory system?
- nicotine in blood vessels cause the blood vessels to narrow, placing strain on circulatory system and results in increased blood pressure
- narrowing of blood vessels also cause the build up of fat globules, increasing the risk of coronary heart disease (CHD).
- the carbon monoxide from cigarette smoking will bind irreversibly to haemoglobin, reducing the amount of oxygen that can be carried in red blood cells, so it increases risk of emphysema (shortness of breath due to insufficient oxygen transport)
131
what is coronary heart disease (CHD)?
it is when the lumen of the coronary arteries is blocked with fat, and irritation of the lining of the arteries causes it to harden until lumen is blocked. this means there's less oxygen taken to the heart, so there is more anaerobic respiration, so lactic acid is produced which causes chest pains (angina). this means less atp is formed, so the muscles stop contracting and die, causing a heart attack
132
what is the method to investigate breathing in humans and the release of carbon dioxide?
1. pour lime water into a boiling tube
2. using the straw, breathe into it
3. note the change in limewater
133
what is the method to investigate breathing in humans and the effect of exercise?
1. measure the breathing rate of the person at rest (breaths/minute)
2. carry out a specific exercise, like star jumps, for 1 minute
3. measure the breathing rate immediately after
4. repeat 2-3 for different intensities of exercise (still the same thing though)
134
how is water absorbed by root hair cells?
high water potential in the soil so water moves by osmosis into the root hair. in the root hair, the water potential decreases so water continues to move. root hair has high surface are for osmosis
135
what is transpiration?
the loss of water from plants, mainly through stomata. it is the process of evaporation of water then diffusion of water out of the cell
136
what is the best humidity for transpiration to occur?
low humidity; lower water potential outside of the leaf
137
what is the best windspeed for transpiration to occur?
windy; wind blows water particles away so low water potential
138
what is the best temperature for transpiration to occur?
warm temperatures; lower water potential
139
what is the best light intensity for transpiration to occur?
bright light; stomata opens for diffusion of carbon dioxide, so water moves by osmosis out of the leaf
140
what is the method to investigate how the rate of transpiration is affected by different environmental factors?
1. set up a potometer
2. cut leafy shoot under water to prevent xylem closing
3. use vaseline at the joints of potometer to reduce water loss
4. set up the necessary environmental factors (temp=temp controlled room/water bath, humidity = wrap in plastic bags with different concentrations of water, windspeed = fan, light intensity = lamp at different distances)
5. record starting place of air bubble on scale
6. leave it for 1 hour
7. record the final position of air bubble, work out distance moved, work out water absorbed
141
what is the excretory product of the lungs?
carbon dioxide
142
what is the excretory product of the kidneys?
water, urea, salts (urine)
143
what is the excretory product of the skin?
excess water and salts
144
what does urine contain?
urea, water, salts
145
how do the kidneys carry out excretion?
ultrafiltration, selective reabsorption
146
where does ultrafiltration occur?
bowman's capsule
147
describe ultrafiltration
thicker arteriole enters the glomerulus, thinner vessel leaving; creates pressure. high pressure causes filtration through the capillaries pores that act like sieves to separate big molecules from small molecules, forming glomerular filtrate
148
what is in glomerular filtrate?
urea, water, salts/mineral ions, amino acids, glucose
149
what was filtered out of the bowman's capsule (too big)?
red blood cells, white blood cells, platelets, plasma proteins
150
what is selective reabsorption?
returns all useful molecule to blood - all glucose, all amino acids, most water - through diffusion, active transport, osmosis
151
why is the proximal convoluted tube specialised for selective reabsorption?
micro villi increase surface are, one cell thick, many mitochondria for atp for active transport
152
where is FSH released from?
pituitary glands
153
what is the effect of FSH?
it causes eggs to mature (forms follicle sac), makes ovaries release oestrogen
154
where is oestrogen released from?
ovaries
155
what is the effect of oestrogen?
rebuilds uterine lining, switches off FSH so that only one follicle is released, stimulates LH release
156
when is oestrogen released?
day 4/5-14
157
where is LH released from?
the pituitary glands
158
what is the effect of LH?
causes ovulation, switches off FSH, stimulates corpus luteum to produce progesterone
159
when is LH released?
day 14
160
where is progesterone released from?
ovaries
161
what is the effect of progesterone?
maintains uterus lining, switches off LH
162
when is progesterone released?
14-28
163
what does the term population mean?
all the individuals of one species in a given area at a given time
164
what does the term community mean?
all the species in a given area at a a given time
165
what does the term habitat mean?
where an organism lives
166
what does the term ecosystem mean?
all living and non-living organisms (abiotic and biotic) in a given area at a given time
167
what is the method to investigate population size in two different areas?
1. put down two 10m tape measures at right angles (like a grid)
2. use a random number generator to get a coordinate and place the quadrat at that coordinate
3. count the number of individuals of the species in the quadrat
4. repeat 2-3 9 more times and work out the mean number
5. estimate population size by using the formula: total area/quadrat area x mean number
6. repeat 1-5 in the other place you are investigating
168
what is biodiversity?
the variety of species living in a habitat
169
what are some biotic factors that effects population size?
predation, competition, disease
170
what are some abiotic factors that affect population size?
- temperature
- sunlight
- soil structure
- windspeed
- rainfall
- CO2 concentration
- pH
171
what is the first trophic level in a food chain?
producer
172
what is the second trophic level in a food chain?
primary consumers
173
what is third trophic level in a food chain?
secondary consumer
174
what is the fourth trophic level in a food chain?
tertiary consumer
175
what are ecological pyramids?
represent numerical relationships between successive trophic levels in a community (they use numbers to represent food chains/webs)
176
what is a pyramid of numbers?
they are a diagrammatic representation of the numbers of different organisms at each trophic level in an ecosystem at one time
177
what is a pyramid of biomass?
they represent the biomass (number of individuals x mass of each individual) at each trophic lever
178
why is energy lost in between trophic levels?
1. respiration
2. in complete consumption (organism may have not eaten all of it eg left the bones)
3. egestion/excretion
179
how much energy is roughly transferred between trophic levels?
10%
180
why is water needed in bread?
activates yeast cells
181
why is flour needed in bread?
starchy, amylase enzymes break it down into glucose for respiration
182
why is yeast needed in bread?
it respires anaerobically and produces carbon dioxide and ethanol
183
what does kneading bread do?
distributes cells evenly and increases surface area
184
what does fermentation do in bread?
it is anaerobic respiration. t must be warm (37 degrees ish) for optimum enzyme activity
the dough rises because of carbon dioxide bubbles from respiration
185
what does lactobacillus do in yoghurt production?
ferments lactose into lactic acid which denatures proteins to make the texture gloopy, and gives it the acidic taste
it ferments to produce lactic acid (anaerobic respiration glucose --> lactic acid)
185
what does baking do in bread?
denatures yeast and enzyme cells so reactions stop
evaporates ethanol so it isnt alcoholic
186
what is the method to investigate anaerobic respiration in yeast in different conditions?
1. measure 10ml of yeast suspension and add to the boiling tube
2. put the boiling tube in a water bath
3. add a bit of oil to cover the top of the solution to prevent oxygen/air getting in
4. connect a delivery tube and a bung to the boiling tube and a test tube half filled with lime water
5. count the number of bubbles produced in one minute
6. repeat 1-5 2 more times and work out a mean
7. repeat 1-6 at different water bath temperatures
187
what is denitrification?
nitrates being made into N2 gas in the atmosphere by denitrifying bacteria
188
what is nitrogen fixation?
N2 in the air being turned into plant proteins (CHON) by nitrogen fixing bacteria in the roots nodules of legumes
or
N2 in the air being made into intrates/ammonium ions by nitrogen fixing bateria in the soil
189
what is decomposition (nitrogen cycle)?
dead organisms being turned into ammonia by decomposers
190
what is nitrification?
ammonia being turned into nitrites by nitrifying bacteria then those nitrites being turned into nitrates by nitrifying bacteria
