Required Practicles Flashcards
(8 cards)
Microbiology ( investigating effects of different antibiotics or bacterial growth using agar plates)
- Disinfect desk
- On the bottom of agar plate mark 3 segments and dot in the middle of each segment
- Was hands
- Place the different antiseptics onto different filter Paper disks
- Lift the lid carefully and place disks onto dots
- Place agar plate in incubator at 25 degrees for 48 hours
- Measure diameter using ruler of clear zone. Dont remove lid
- Record in table
To get area do pi r ²
Osmosis ( find the change in length or mass of plant tissue in a range of concentrations)
- Use Cork borer to cut 5 potato cylanders
- Trim cylanders till exactly the same length
- Accurately measure, record the length and mass of each cylander
- Measure 10cm³ of the 1.0 sugar solution and transfer to first boiling tube
- Repeat for other concentrations and distilled water
- Add one potato cylander to each tube
- Leave overnight
- Remove and gently blot dry with paper towel
- Measure length and mass of each cylander and record percentage change
Iodine test
Mush up food with distilled water
Add iodine solution
If starch is present the solution will turn from brown to blue black
Benedicts test
Mush up food with distilled water
Add equal volume of benedicts solution
Place in hot bath for a few minutes
If sugar is present a brick red precipitate will form if not it will remain blue
Test for protein (biurets reagent)
Mush up food with distilled water
Add biurets reagent
Shake to mix and wait
If present solution turns from blue to purple
Test for lipids (emulsion test)
Add a few cm³ of ethanol to food sample
Poor into test tube with equal volume of distilled water
If lipids is there a white emulsion is formed on surface of liquid
Enzyme ( investigate effect of pH on rate of reaction of amylase
- Place single drop of iodine on each of the tiles
- Label test with pH to be tested
- Add 1 cm of pH buffer solution to test yube
- Use another test tube to add 2cm³ of starch solution to the amylase and buffer solution
- Start timer while mixing
- After 10 seconds use pippete to add 1 drop of mixture on first iodine drop and it should turn blue black
- Repeat until iodine solution remains browny orange
- Repeat at different pH, the shorter time it takes the better the enzyme works at that pH
Photosynthesis ( effect of light intensity on rate of photosynthesis using a plant)
Place a test tube containing a boiling tube 10cm away from light source
Fill with fixed volume of sodium hydrogen carbonate solution
Place cut pond weed into boiling tube with cut end at top and use glass rod to push down
Leave for 5 minutes
Start stopwatch for a minute and count amount of bubbles
Repeat twice for each light intensity to find mean
