Required Practicals Flashcards
(6 cards)
Animal and plant cells - parts of microscope
-Microscope slide placed on centre of microscope called stage
-Lamp below stage shines light up to slide
-Three objective lenses above stage with different magnifications#
-Eyepiece to look through at the top, containing the eyepiece lens which has a magnification of 10x
Animal and plant
cells - Using a light
microscope
-Place slide onto stage, using clips to hold in place
-Select lowest power objective lens and position it so it almost touches the microscope slide
-By slowly turning the coarse focusing dial
-Observe the microscope from the side while adjusting the position of the objective lens
-Stop turning dial when it is almost touching the slide
-Only look through eyepiece after the lens is positioned to avoid damaging the slide
-Turn coarse focusing dial until cells come into focus
-Then turn fine focusing dial until cells come into clear focus
-Repeat for higher magnification
Aseptic technique
-Culture bacteria using nutrient broth solution or agar gel plate
Aseptic technique:
-Sterilise petri dishes, bacterial nutrient broth and agar to kill unwanted microorganisms and prevent contamination
-Sterilise inoculating loop by passing through a flame
-Attach lid of petri dish using adhesive tape to stop pathogens entering/lid falling off
-Place agar plate upside down in incubator to stop moisture dripping onto bacteria, disturbing the colonies
-Bacteria incubated at 25 degrees to prevent growth of harmful bacteria
Practical - effect of antibiotics on growth
- Sterilise bench with disinfectant to kill unwanted organisms
- Sterilise inoculating loop by passing through flame
- Open sterile agar gel plate near Bunsen burner flame to kill airborne bacteria
- Use loop to spread chosen bacteria evenly
- Place sterile filter paper discs containing antibiotic onto the plate
- Incubate at 25 degrees
Practical - effect of pH on amylase
- Place one drop of iodine solution into each well of a spotting tile
- Get 3 test tubes:
-Test tube A has 2cm3 of starch solution
-Test tube B has 2cm3 of amylase solution
-Test tube C has 2cm3 of pH 5 buffer solution - Place all test tubes in a water bath at 30 degrees for 10 mins until reached the correct temp
- Combine the three solutions to one tube and return to water bath while stirring. Start a stopwatch
- Every 30 seconds, place a drop of the solution onto the tile until the iodine remains orange - the reaction has finished
- Measure time taken for reaction to finish and repeat for other types of pH
What are the issues of this practical and how can we overcome them?
Only taking 30 sec samples so the time taken is an estimate
-Could take more frequent samples e.g. every 10 sec
It is a gradual change so there may be some blue-black left in the orange mix
-Can ask multiple people to observe and decide when the reaction has finished
