B7 Flashcards
Able to be reproduced if someone else was to carry out the same experiment
Reproducible or accurate
How close a value is to the correct value
Precise
How to focus on a microscope
Select the lowest level of magnitude
Move the objective lens as far away from the slide
Using the coarse- focus knob, gradually bring it into focus
As the image clears, use the fine focus knob to bring an image into sharp focus
Microscope - which way do the lenses go from the top to bottom
Objective lens (looks at the image, there are 3 settings (4, 10, 40)) Coarse adjustment knob Fine adjustment knob (moves the stage up and down)
Test for starch
Add some drops of iodine.
It will stain hands so gloves required.
Should turn blue/black
Test for fat
Add a few drops of ethanol, shake and allow to stand for 1 minute. Pour the ethanol into a test tube of water.
Ethanol is flammable
Should change to cloudy
Test for protein
Add some drops of copper Sulfate solution, then some drops of sodium hydroxide solution.
Copper Sulfate is harmful
And the sodium hydroxide is an irritant
Should turn from blue to purple
Test for glucose
Add some drops of Benedict’s solution to the substance and heat in a water bath.
Should change from blue to orange-red.
Abiotic factors to monitor
Temperature
Dissolved oxygen content
pH
Moisture content
How to find the optimum conditions for amylase to digest starch
- Select what you need to investigate
- Add a drop of iodine solution into each dimple of a spotting tile
- Add starch solution and amylase into a boiling tube
- Remove a drop of enzyme or starch moisture every 10 seconds and add to iodine on the dropping tile
- At the point where there is no colour change in the iodine is when all the amylase has fully digested the starch and note this time.
Repeat 3 times.
Advantages of using a water bath
Helps keep to a constant temperature
Provides a reliable method when the temperature is the independent variable
Also better for any flammable solutions (ethanol)
Investigating the rate of photosynthesis of cabomba
- Select what factor you want to investigate
- Place samples of cabomba into dilute sodium hydrogen carbonate solution
- Measure the time taken to produce 50 bubbles of oxygen gas
Repeat for other values.
Investigate the effect of fitness on heart rate
- Select groups of students to be studied. (Ex. Athletes vs. Those that don’t exercise)
- Select how you want to measure the fitness (ex. Recovery time)
- Take a baseline fitness measurement
- Ask each person to undertake the physical activity for 30s
- Retake and repeat
Aseptic techniques
Wash down the working areas with alcohol
Do the experiment near a Bunsen burner
Sterilise equipment before and after use
Investigating the antibiotic effect of household equipment
- Prepare an agar plate with bacterial culture growing on it.
- Divide it into 4 sections (quadrants)
- Dip a sterile paper disc into the first agent to be tested and place in the corresponding section.
- Repeat for everything else.
- Seal with sticky tape (but not airtight)
- Turn upside down and incubate for 48 hours
- Without opening the plate, measure the zone of inhibition around each antimicrobial agent.
