AQA - GCSE Required Practicals - Trilogy Science

Biology

, S

Microscopy - - Ensure you h
c

- Carry the m
Apparatus:

- Light Microscope - Use Iodine
- Glass Slide
- Onion Skin
- Iodine Magnification = I
- Glass Cover Slip
- Forceps


Method:

- Ensure the microscope is plugged in and turned on

- To prepare your onion slide – Grab the glass slide by the edges to avoid making the slide greasy with your fingers

- Peel off a layer of onion skin by using your fingers or forceps and place in the middle of the slide ensuring there are no creases or folds

- Stain your onion skin with around 3 drops of iodine and place a glass cover slip over the top

- Secure the slide to the stage with the clips ensuring that the cover slip faces up towards the objective lens

- Before using the microscope, check that the lowest objective lens has been selected

- Look into the microscope and use the coarse and fine focusing knob to make the image clearer and sharper

- Switch the objective lens to a higher power/magnification and refocus




Watch this video for more information: https://www.youtube.com/watch?v=SX6mow1AExI&list=PLAd0MSIZBSsHv1pioWRdg-pZCWTo84cdP

, S

Osmosis - - Ensure you h
c
Apparatus:
- Carry the m
- Potato
- Cork Borer
- Knife - Use Iodine
- Ruler
- Balance
- Boiling Tube - Independen
- Distilled Water Type/
- 0.25 Molar Sucrose
- 0.5 Molar Sucrose - Depende

Method: - % Change = C
M
- Using a cork borer cut 3 cylinders out of a potato

- Cut off the ends as they are impermeable

- Measure and cut each cylinder to 3cm lengths

- Measure the mass and length of each potato cylinder and table the results

- Fill each boiling tube with the 3 different solutions measured at 10cm3 and label

- Put in the potato cylinder and cover with bung to prevent loss of solution through evaporation

- Put in the potato cylinder and cover with bung to prevent loss of solution through evaporation

- Wait for about a day, remove the potato from the tube, pat down the paper towel to remove extra moisture

- Remeasure the masses of the potato cylinders and calculate the change in mass




Watch this video for more information: https://www.youtube.com/watch?v=oieXYuQm_xE&list=PLAd0MSIZBSsHv1pioWRdg-pZCWTo84cdP&index=2

, Rate of Photosynthesis - S

- Keep all glas
Apparatus: t

- Pondweed - Use the
- Lamp/Light Source
- Clamp - Be careful w
- Test Tube/Boiling Tube
- Sodium Hydrogen Carbonate Solution
- Stopwatch
- Ruler - Independent Variable:

- Dependent Variable: Ra
Method:
- Photosynthesi
- Take a piece of pondweed and put it into the test tube
Carbon Dioxide + Water →
- Fill the tube with Sodium Hydroxide Carbonate which encourages the pondweed to photosynthesis
- Symbo
- Make sure the pondweed is fully submerged, then cut the stem at an angle to help see the oxygen production/bubbles clearly
6CO2 + 6H2O → C
- Turn on your lamp/light source and begin to count the number of oxygen bubbles produced in a minute

- Record this data

- Change the distance of the pondweed from the light and measure the number of bubbles produced in 1 minute

- Put the pondweed near and further away from the light source to get a range of results at intervals of 10cm




Watch this video for more information: https://www.youtube.com/watch?v=id0aO_OdFwA&list=PLAd0MSIZBSsHv1pioWRdg-pZCWTo84cdP&index=4