Practicals Flashcards
Test for Glucose
Benedict’s Solution
Water at 80 degrees Celsius for 5 minutes
Blue —> Brick red (green, yellow, orange for lower conc)
Test for starch
Iodine
Spotting tile
Orange/brown —> blue/black
Test for protein
Buiret
Blue —> lilac/purple
Test for lipids
Ethanol - Shake
Water - Shake
Colourless —> cloudy white
Investigate how enzyme activity can be affected by changes in temperature
- Add starch solution to a test tube
- Heat to set temp using Bunsen burner
- Add iodine
- Add amylase
- Every minute, transfer a drop of solution to a new well of iodine solution (on a spotting tile)
- This will turn blue/black
- Repeat this process until the iodine stops turning blue/black
- Record the time taken for the reaction to be completed
IV: Temp
DV: Time taken for amylase to denature (for the iodine to stop turning blue/black)
CV: Volume, pH etc
Investigate diffusion in non - living systems
- Agar cubes contain alkaline + indicator
- Placed in acid
- As the acid diffuses into the cube it reacts with the alkali
- This turns the indicator colourless
Temp: Change temperature, same size agar cubes
SA:VR: Size of agar cubes
Concentration: Change concentration, same size agar cubes
Rate of osmosis (living)
- Cut potatoes with cork borer
- Weigh
- Put in sucrose of salt solutions with ranging concentrations
- Leave for period of time
- Take out of solution, blot with paper towel and reweigh
Rate of osmosis (non - living)
- Add distilled water to visking tubing
- Weigh
- Put in sucrose or salt solutions with ranging concentrations
- Leave for period of time
- Take out of solution and reweigh
Investigate photosyntheses (light, CO2 conc, chlorophyll)
- Destarch a leaf by placing it in a dark cupboard for 48 hours (to make sure any starch present in the leaves is used up and won‘t affect results of experiment)
- Light: Cover part of leaf with foil
- CO2 concentration: put one leaf in a plastic bag with soda lime
- Chloroplasts: use a variegated leaf
- Leave in sunlight for period of time
- Put leaf in boiling water (to kill the tissue and break down cell walls)
- leaf in hot ethanol (flammable) for 5 minutes (to remove chlorophyll so colour changes from iodine can be seen clearly)
- Rinse leaf in cold water (to soften leaf after ethanol)
- Add iodine
- Areas that contain starch will be blue/black
Investigate energy content in a food sample
- Set up clamp to hold boiling tube
- Add water into boiling tube + measure the starting temp
- add thermometer into test tube
- weigh mass of food and set on fire
- Hold food sample under boiling tube
- relight food sample if it stops burning
- Repeat until food sample no longer catches fire
- Measure temp of water
Energy content = temp change x volume of water x 4.2/mass of food x 1000
Investigate the evolution of carbon dioxide and heat from living organisms
- Flask A: live pea seeds (soaked in Milton solution to kill other respiring organisms and ruining experiment)
- Flask B: Dead pea seeds - also soaked in Milton Solution
- Measure starting temp
- leave for period of time
- Measure ending temp
- Collect gas produce + bubble through limewater (turns cloudy for flask A only)
Investigate breathing in humans and the effects of exercise
- Measure Student A‘s resting breathing rate (measure their number of breaths for 30 seconds then double)
- find an average
- Student A should exercise for a set time
- immediately count their breathing rate
- calculate the change in breathing rate
Repeat to find means after a period of rest
Investigate the role of environmental factors in determine the rate of transpiration (potometre practical)
- Set up potometre underwater to air bubbles forming
- Cut shoot underwater and secure in potometre with bung to prevent water loss and air entry
- Make sure tap is closed and full of water
- Lift potometre out of water
- Leave end of capillary tube out of water until air bubble forms then put in a beaker of water
- measure the transpiration rate as the distance moved by the bubble in a set time
Light: turn lights on/off
Wind: Hair dryer on cold
Humidity: Change the humidity
Temp:
Investigate the population size in two different area using Quadrats
- calculate area of habitat
- create 10x10 grid
- use phone/calculator to generate a random number to create coordinates
- place Quadrat at coordinates
- Count number of organisms methodically
- Repeat
- Work out how many Quadrats fit in area
- Times step 5 by 7
Make yoghurt
What is the bacteria used called???
Bacteria: Lactobacillus Bulgarius
- Sterilise equipment to remove unwanted bacteria and other competitions
- Heat milk to remove bacteria
- Cool milk to 40 degrees Celsius and add lactobacillus
- Lactobacillus bulgarius converts milk lactose into lactic acid which sours and thicken the milk
- yoghurt is stored and cooled to 5 degrees Celsius to halt lactobacillus
