Practicals paper 2 Flashcards
Plant growth pracitcal
1) Put cotton wool into three petri dishes, and add the same volume of water to each dish.
2) Add ten seeds to each dish and place them in a warm place where they won’t be disturbed.
3) Allow the seeds to germinate, and add more water if the cotton wool dries out.
4) Once the seeds have germinated, ensure the petri dishes each contain the same number of seeds, and remove any extra seeds if necessary.
5) One petri dish will sit in full light on a windowsill, the second will be in a dark cupboard, and the final dish will be placed in partial light.
6) Every day for one week, measure the height of each seedling and record the results in a table. You must record the height of the individual seedlings on each day.
7) Calculate the mean of the seedlings each day, and compare the mean heights in the three different locations.
Milk decay practical
1) Measure out 5m3 of lipase solution and add it to a test tube, label it
2) add 5 cm3 of milk to a different test tube, label it milk
3) Use universal indicator paper or 5 drops of phenolphthalein to determine the pH of the milk in the three beakers
4) add 7cm3 of sodiuim carbonate solution and add iot to the tube containing ilk and phenolphthalein, this makes the solution in the tube alkaline, so it should turn pink
5) put thermometer in the test tube containing milk
6) put both of the test tubes in a hot water bath at a chosen temperature, 20 degree
7) When the temperatures of our solutions reach 20 degrees, put 1cm3 of the lipase solution into the milk tube and start a stopwatch straight away
8) stir the contents of the tube with a glass tube the enzyme will start to decompose the milk, breaking the fat molecules, releasing fatty acids, which causes the milk solution to become acidic
9) the indicator will turn white, as soon as this happens stop the stopwatch and record how long the colour change took in a table
10) repeat the experiment with a range of different temperature
11) calculate the rate decay in the untis s-1
rate = 1000/time
