How enzyme activity can be affected by changes in temperature
- Add starch and amylase solution in boiling tubes, heat inside a beaker of water at 20 degrees for 5 minutes
- Add a drop of iodine to the spotting tiles
- Amylase solution is poured into the starch suspension, mix well
- Add a drop of the solution with a pipette, adding a new drop every 30 seconds, stopping when the iodine solution stops turning blue black
- Record the time taken for the reaction to be completed
- Repeat for a range of temperatures
Improvements
-use water baths kept at each temperature, uniform heating
-starch and amylase can be placed in a water bath and allowed to reach the temperature before being used
Safety
-glasses
How does pH affect enzyme activity PAPER 2 ONLY
- Add a drop of iodine into wells of a spotting tile
- Use a syringe to place 2cm of amylase into a test tube
- Add buffer solution into the test tube using a syringe
- Use another test tube to add starch solution to the amylase and buffer solution
- Start the stopwatch ,while mixing using a pipette
6.every 10s transfer a droplet of the solution to a new well of iodine solution - Repeat until the iodine solution stops turning blue black
- Record time taken to be completed
- Repeat with buffers at different pH values
Improvements
-starch and amylase van be placed in a water bath at optimum temperature before being used
Safety
-goggles
Investigate diffusion in a living thing
- Cut 2 equally sized cubes of beetroot, with same dimensions, volume and SA
- Rinse beetroot (remove any pigment released during cutting)
- Add to test tubes with water
- Heat one to 90 degrees, the other remains room temp
- Once fully heated, add both beetroot to their test tubes
- After 10 mins, observe the colour of hate liquid in both test tubes (higher temp is more purple)
Improvements
-cut the beetroot with a ruler and knife
-range of temperatures, repeat each temperature many times
Safety
-goggles
-use tongs when handling the hot test tube
Investigate osmosis in a living thing
- Range of sucrose solutions at regular intervals (20) from 0mol/dm to 1 mol/dm
- Add to a test tube
- Using a cork borer and ruler and knife, cut 6 equally sized cylinders of potato
- Dry each potato with a paper towel and weight on the balance
- Put 1 piece into each concentration of the sucrose
- After 4 hours, remove them, blot with paper towels and reweigh them
Improvements
-repeat each one with several potato cylinders as each they have all variations between them
-repeat
Safety
-goggles
Investigate diffusion in a non living thing
- cut 3 agar jelly into cubes, all different dimensions
- Dye them purple with potassium permanganate
- Add all 3 into the same beaker containing hydrochloric acid
- HCl will move into the agar, and make the purple colour disappear
- Record time taken for each one to fully turn colourless
Improvements
-repeat many times
Safety
-safety goggles
-avoid skin contact with acids and dyed agar
Practical to show evolution of oxygen from a plant
- Take a bundle of shoots from the same type of pondweed
- Submerge them in a beaker 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, displacing the water for 5 minutes
(CAN ALSO DO QUANTITY OF BUBBLES)
-can show it is oxygen by relighting a glowing splint
Safety
-wash hands after collecting and preparing pondweed
Investigate light in photosynthesis
- De starch the lead by placing it in a dark cupboard for one day (starch will be used up)
- Partially cover a leaf of the plant with aluminium foil and place the plant in sunlight for a day
- Remove covered leaf, place in boiling water to kill tissue and break cell wall (stops chemical reactions and allows iodine to reach chlorophyll)
4.transfer leaf into hot ethanol in a boiling tube for 5 minutes, removes chlorophyll (so colour change from iodine can be seen more clearly, stops it from photosynthesising) - Rinse the leaf in cold water, to soften the leaf
- Spread leaf on a white tile and cover it with iodine
- The part of the leaf exposed to sunlight with turn blue black as there is starch
Improvements
-repeats
Safety
-ethanol is flammable, so Bunsen burner should be turned off
-or use a water bath instead of a Bunsen burner
How to investigate carbon dioxide in photosynthesis
- de starch the plant (same as before with no sunlight etc)
- Enclose one leaf with a conical flask containing potassium hydroxide, will absorb CO2 from the surrounding air
- Other leaf do not enclose with potassium hydroxide (do not remove leaf from plant, ensure airtight)
- Leave both for several hours in bright light
- Test for starch same as before with boiling water and ethanol
- Leaf with carbon dioxide will become blue black
Practical to investigate chlorophyll
- Place a variegated leaf in boiling water and then ethanol for 5 minutes to remove chlorophyll
- Rinse the leaf in cold water
- Spread leaf out on a cover with iodine solution
Results:
-previously green area will be blue black, else orange brown
Investigate energy content in a food sample PAPER 2 ONLY
- Use measuring cylinder to measure out 25cm of water
- Record starting temperature
- Record mass of food sample
- Set fire to the food sample of food using Bunsen burner underneath the boiling tube of water
- Keep igniting until burnt completely
- Measure final temperature
- Repeats and average
- Formula is energy transferred per gram of food = (mass of water (g) x temp increase (c) x 4.2)/mass of food sample(g)
Reasons for limitation
-incomplete burning
-heat energy lost to surroundings
Practical to investigate respiration and evolution of carbon dioxide
- Measure 10cm of hydrogen carbonate indicator into 3 boiling tubes
- Places layer of cotton wool
- Place 10 germinating seeds in tube a, 10 dead/boiled seeds in tube b and 10 glass beads in tube c
- Set each tube with a rubber bung
- After 3 hours observe the colour of the indicator
High CO2 = yellow
Normal CO2 = red
Low CO2 = purple
All stay red except for germinating seed, turns yellow
Practical to investigate heat from respiration
- One flask with dead seeds, other with germinating seeds. All should have cotton wool
- Invert the flasks and use cotton wool as a bung with a thermometer going up into the flask (carbon dioxide is denser than air, allows it to escape and not kill the seeds
- Leave for a couple of days, measuring start and end temperature
Investigate effect of light on gas exchange in plants PAPER 2 ONLY
- Measure out 20cm of hydrogen carbonate indicator into 4 boiling tubes
- Put cotton wool into each boiling tube
-one boiling tube with no leaf - stays red
-one boiling tube with leaf and leave in light - becomes purple
-one boiling tube with leaf and foil around to block light - becomes yellow
-one boiling tube with leaf and gauze for partial light - stays red (photosynthesis = respiration rate)
Investigate breathing in humans
- Record number of breaths a person take when sitting down for 15s then multiply by 3
- Exercise for 5 minutes such as running, they should be resting before. Record their breathing rate every 15 seconds. Do this every minute until they return to normal breathing rate
- Use calculate the breathing rate for both per minute
- 10 participants, repeat and average for mean
Fit person’s resting rate is lower, increases the breathing rate slower, and decreases breathing rate faster after exercise,
Practical to compare composition of inhaled and exhaled air
Look in the textbook, page 44
How to carry find rate of transpiration
- Photometer
- Cut shoot underwater to stop air bubbles blocking xylem
- Assemble equipment underwater to ensure no air is in it
- Ensure it is airtight
- Introduce bubble by lifting the tube out of the water, so there is an air bubble
- Open the reservoir tap to position the air bubble
- Measure how far the bubble moves with a ruler
- 2 minutes
- 5 minutes
- Rate of transpiration = distance the bubble moved/time period
For independent variable
-fan for wind
-spray water in transparent plastic bag and wrap around plant for humidity
-temperature of room
-light: distance of lamp
Practical investigate conditions needed for seed germination
- Prepare 4 test tubes with 10 cress seeds on cotton wool
-A: keep cotton wool dry
-B: moisten the cotton wool with water
-C: submerge seeds and cotton wool with water and a layer of oil on top
-D: moisten the cotton wool and place the tube in a fridge at 4 degrees
Other test tubes at 20 degrees - Compare the number of germinated seeds in each tube
- Only second one will germinate, shows oxygen, water and warmth is needed
Investigate population sizes of habitats
- Use two tape measures to lay out the survey area in the chosen habitat
- Use a random number generator to create a set of coordinates to place you first quadrant
- Count the number of your chosen plant species that are found within this quadrant
4.estimate the population of dandelions using your two survey area
Improvements
-use a pencil to move leaves out of the way to check if there us anything else underneath
Other
-for percentage cover see the approximate number of squares it covers
Investigate the distribution of organisms PAPER 2 ONLY-
- Use 2 tape measures to lay out your first survey area
- Use a random number generator to create a set of coordinates to place first quadrant
- Count number of different species found within that quadrant
- Repeat 10 times
- Repeat this for the second area
Improvements
-check under plants for more plants
Investigate anaerobic respiration in yeast
- Mix yeast with sugar solution in a boiling tube
- Carefully add a layer of oil on top of the solution to prevent oxygen from entering the solution
- Use a capillary tube to connect it to another boiling tube with limewater
- Place in a water bath and count the number of bubbles produced in a fixed time
- Change the temperature of the water bath and repeat
-can do with buffer solution as well
How is the structure of the leaf adapted for its function
-thin
-large surface area
-upper epidermis/cuticle
-transparent, lets light through
-palisade
-chloroplasts with chlorophyll
-close to surface
-absorb light
-spongy mesophyll
-diffusion
-stomata/guard cells
-carbon dioxide
-xylem
-water
Small intestine adaptations
-long
-villi/microvilli
-increase surface area
-diffusion/active transport
-capillaries
-blood flow maintains concentration gradient
-one cell thick capillaries and villi = short diffusion distance
-lacteals
How does CHD lead to death
-blocked
-coronary artery
-clot (when the plaques ruptures, blood clots, blocking flow of blood)
-fat/cholesterol
-less blood to heart
-less oxygen
-muscle
-less respiration/anaerobic respiration
-lactic acid
-heart attack
Consequences of smoking on the lungs
-emphysema
-less surface area in alveoli
-bronchitis
-bacteria/infection
-cilia damaged
-buildup or more mucus
-cancer
-tar
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Ecology68
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Transpiration30
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Kidney30
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Co-ordination101
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characteristics of living organisms19
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Biological Molecules18
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movement of substances13
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nutrition55
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gas exchange in plants4
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transport32
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respiration15
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gas exchange in humans27
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Human Repoduction45
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Genetics73
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Natural Selection16
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Food Production41
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Genetic Modification17
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Set Practicals50
