p2 practicals Flashcards
(5 cards)
investigate how enzyme activity can be affected by changes in PH
Add a drop of iodine to each of the wells of a spotting tile
Use a syringe to place 2 cm3 of amylase into a test tube
Add 1cm3 of buffer solution (at pH 2) to the test tube using a syringe
Use another test tube to add 2 cm3 of starch solution to the amylase and buffer solution, start the stopwatch whilst mixing using a pipette
Every 10 seconds, transfer a droplet of the solution to a new well of iodine solution (which should turn blue-black)
Repeat this transfer process every 10 seconds until the iodine solution stops turning blue-black (this means the amylase has broken down all the starch)
Record the time taken for the reaction to be completed
Repeat the investigation with buffers at different pH values (ranging from pH 3.0 to pH 7.0)
investigate the energy content in a food sample
Use the measuring cylinder to measure out 25 cm3 of water and pour it into the boiling tube
Record the starting temperature of the water using the thermometer
Record the mass of the food sample
Set fire to the sample of food using the bunsen burner and hold the sample 2 cm from the boiling tube until it has completely burned
Record the final temperature of the water
Repeat the process with different food samples
investigate the effect of light on the net gas exchange from a leaf, using hydrogen - carbonate indicator
Measure out 20 cm3 hydrogencarbonate indicator into 4 boiling tubes
Put some cotton wool into each boiling tube
Label the boiling tubes A-D and set them up as follows:
Tube A - No leaf (control tube)
Tube B - Place a leaf in the tube and leave in the light
Tube C - Place a leaf in the tube and wrap it in aluminium foil to block out the light
Tube D - Place a leaf in the tube and wrap it in gauze to allow partial light
Put a bung into the top of each tube
Leave all 4 tubes in the light for 30 minutes
investigate the role of environmental factors in determining the rate of transpiration from a leafy shoot
Cut a shoot underwater
To prevent air entering the xylem and place in tube
Set up the apparatus as shown in the diagram and make sure it is airtight, using Vaseline to seal any gaps
Dry the leaves of the shoot
Wet leaves will affect the results
Remove the capillary tube from the beaker of water to allow a single air bubble to form and place the tube back into the water
Set up a lamp 10cm from the leaf
Allow the plant to adapt to the new environment for 5 minutes
Record the starting location of the air bubble
Leave for 30 minutes
Record the end location of the air bubble
Change the light intensity
Reset the bubble by opening the tap below the reservoir
Repeat the experiment
Calculate the rate of transpiration by dividing the distance the bubble travelled by the time period
