BIOLOGY

Question 1

B1.2 - ‘Looking at cells’ practical steps:

Answer 1

1 Collect a sample of the cell you want to observe.
2 Remove the inner skin of a layer of onion using forceps
3 Place the thin slice onto a clean glass slide. Use your forceps to keep the onion skin flat on the glass slide.
4 Using a pipette, add one or two drops of dilute iodine solution on top of the onion skin or slice of algae or plant.5 Hold the coverslip by its side and lay one edge of the cover slip onto the microscope slide near the specimen.
6 Lower the cover slip slowly so that the liquid spreads out.
7 Move the stage to its lowest position.
8 Place a prepared slide on the centre of the stage and fix it in place using the clips.
9 Select the objective lens with the lowest magnification.
10 Look through the eyepiece and turn the coarse focus adjustment until the cells on the slide come into view.
11 Turn the fine focus adjustment to sharpen the focus so the cells can be clearly seen.
12 If you wish to view the object at greater magnification to see more detail, repeat the above steps using a higher magnification lens.

Question 2

B1.8 - ‘Investigating osmosis in plant cells’ practical steps

Answer 2

Your task is to find out how vegetable chips change when left in pure water compared to salty or sugary water (a solution).

Question 3

B3.3 - Food Tests

Answer 3

On Miss Lee’s flashcards.

Question 4

B3.6 - The effect of pH on the rate of reaction of amylase

Answer 4

1​Use the syringe to place 2 cm3 of amylase solution into a test tube.
2​Use another syringe to add 1 cm3 of pH buffer solution to the test tube.
3​Place the test tube into a water bath set at 30 °C and leave for 5 minutes.
4​Whilst waiting, add a drop of iodine solution into each dimple of a spotting tile.
5​After 5 minutes, use another syringe to add 2 cm3 of starch to the amylase/buffer solution, start the stop clock and leave it on throughout the test. Mix using a plastic pipette.
6​Remove a drop of amylase/starch/buffer mixture after 30 seconds and add to the first drop of iodine on your spotting tile. (Hint – the iodine solution should turn blue–black.)
7​Wait another 30 seconds. Then remove a second drop of the mixture to add to the next drop of iodine.
8​Repeat step 6 until the iodine solution and the amylase/buffer/starch mixture remains orange. (Hint – this is the point at which the amylase has fully digested the starch.)
9​Record the time taken for the amylase to fully digest the starch. (Hint – count how many iodine drops you have used.) Multiply the number of drops by 30, as each drop equals 30 seconds of reaction time.
10​Repeat the whole procedure with a different pH buffer.

Question 5

B8.2 Light intensity and the rate of photosynthesis

Answer 5

In photos 22:07 favoourites

Question 6

B10.2- Measuring reaction times

Answer 6

Favouirtes