Required Practicals Flashcards
1
Q
How to investigate the effects of osmosis on plant tissue
A
- Peel the potato as the skin can affect osmosis
- Produce three cylinders of potato using cork borer
- Trim the cylinders to the same length using a scalpel
- Measure length of each cylinder using ruler and measure the mass of each cylinder using a balance
- Place each cylinder into a test tube and add 10cm3 of a 0.5 molar sugar solution to first test tube
- Add 10cm3 of a 0.25 molar sugar solution to the second test tube and 10cm3 of distilled water to the third test tube
- Leave the potato cylinders overnight to allow osmosis to take place
- Remove the potato cylinders and gently roll them on paper towel to remove any surface moisture
- Measure length and mass of cylinders again and use the results to calculate the percentage change
2
Q
How do you calculate percentage change
A
Change in value/original value x 100
3
Q
How to carry out the test for starch
A
- Grind food sample with distilled water using a mortar and pestle
- Transfer paste to a beaker and add more distilled water and stir so the chemicals in the food dissolve in water
- Filter the solution to remove suspended food particles
- place 2cm3 of food solution into a test tube
- Add a few drops of iodine solution
- If starch is present then iodine solution will turn from orange to blue black
4
Q
How do you test for sugars
A
- Grind food sample with distilled water using a mortar and pestle
- Transfer paste to a beaker and add more distilled water and stir so the chemicals in the food dissolve in water
- Filter the solution to remove suspended food particles
- Place 2cm3 of food solution into a test tube
- Add 10 drops of Benedict’s solution
- Place the test tube containing the solution into a beaker and Half fill the beaker with hot water from the kettle and leave it for 5 minutes
- If sugars are present the solution will turn from blue to brick red
5
Q
How to test for protein
A
- Grind food sample with distilled water using a mortar and pestle
- Transfer paste to a beaker and add more distilled water and stir so the chemicals in the food dissolve in water
- Filter the solution to remove suspended food particles
- Take 2cm3 of food solution and place into a test tube
- Add 2cm3 of biuret solution
- If proteins are present then the solution will turn from blue to purple
6
Q
How to test for lipids
A
- Grind food sample with distilled water using a mortar and pestle
- Transfer paste to a beaker and add more distilled water and stir so the chemicals in the food dissolve in water but do not filter solution
- Transfer 2cm3 of solution to a test tube
- Add a few drops of distilled water and a few drops of ethanol
- Gently shake the solution
- If lipids are present then the solution will turn from colourless to form a white cloudy emulsion
7
Q
How to set up and use a microscope
A
- Place your prepared slide onto the stage and use the clips to hold it in place
- Select the lowest power objective lens
- Use the coarse focussing knob to move the stage up, just below the objective lens
- Look down the eyepiece and slowly use the coarse focussing knob to move the slide downwards until the image is roughly in focus
- Use the fine focussing knob to adjust the focus until you get a clear image
- If you need to see the slide with greater magnification, swap to higher powered objective lens and repeat the steps until focus.
8
Q
Culturing microorganisms
A
- Clean the bench using disinfectant solution to kill by microorganisms that could contaminate our culture
- Sterilise an inoculating loop by passing it through a Bunsen burner flame
- Open a sterile agar plate near a Bunsen burner flame
- Spread the chosen bacteria evenly over the gar plate using the inoculating loop
- Place sterile filter paper discs containing different types or concentrations of antibiotics onto the plate, evenly distributed
- Attach Petri dish lid to the plate using adhesive tape
- Place plate upside down onto an incubator
- Incubate plate at 25*C for at least 48 hours
