REQ Practicals Flashcards
Objective: Bio GCSE practicals (106 cards)
1
Q
What is the aim of the microbiology practical
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Aim: To investigte the effect of antisepctics or antibiotics on bacteria growth & measuring zones of inhibition
2
Q
What is the aim of the microscopy practical?
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Aim: To use a light microscope to observe draw & label a selection of plant & animal cells.
3
Q
What is the independent, dependent, and
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4
Q
What is the independent
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dependent
5
Q
practical? Independent: Solute concentration
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6
Q
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7
Q
Dependent: Change in mass of potato cylinder
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8
Q
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9
Q
Control:
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10
Q
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11
Q
- Temperature
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12
Q
- Surface area of potato
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13
Q
- Volume of solute solution
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14
Q
How can you figure out the size of a cell? * You place a ruler on the eyepiece of the microscope
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and measure it
15
Q
- You then magnify it using triangle below:
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16
Q
What are the independent
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dependent
17
Q
practical? Independent: Light Intensity
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18
Q
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19
Q
Dependent: No. of bubbles produced
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20
Q
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21
Q
Control:
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22
Q
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23
Q
- Temp. of water (you can use an LED lamp to achieve this & a thermometer to
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24
Q
ensure temp. remains constant)
A
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* Conc. of carbon (can control this w. sodium hydrogencarbonate)
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* Pondweed (use the same piece of plant)
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What is the aim of the osmosis practical? * To investigate the range of concentrations of salt or sugar solutions on the
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mass of plants.
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What is the aim of the enzyme practical? Aim: To investigate the effect of the pH on the rate of reaction of amylase ( an
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enzyme that breaks down starch)
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Explain how you test to starch * No temp. change necessary
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* You prep. the food
by crushingit or mushing it w. a pestle & mortar
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* Add food sample (eg. potatoes) to a test tube
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* Add a few drops of iodine
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* If starch is found
it will turn blue-black. If not
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STARCH: ORANGE --> BLUE/BLACK
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What is the aim of the food test practical? Aim: to test for the presence of carbohydrates
sugars
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food
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Explain the enzyme practical * Place single drops of iodine solution into rows on a tile.
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* Label a test tube w/ the pH to be tested
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* Add 2cm3 of amylase to the test tube
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* Add 1cm3 of buffer solution to test tube
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* In another tube
add 2cm3 of starch solution to the amylase & buffer
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solution
start stopwatch & mix pipette
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* Every 10 seconds
take a drop of the test tube amylase solution & put it into
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each tile
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* Repeat experiment w. diff. pH values
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* The less time taken to become orange/brown
the quicker the starch has been
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digested & works better in the pH
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Explain the osmosis practical * Use a cork borer to cut 5 potato cylinder of the same diameter (so diameter
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remains the same
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* Cut it with a scalpel & trim the cylinders so that they are the same length
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* Measure the intial mass of each cylinder & record on table
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* Measure 10cm3 of sugar/salt solution & pour into each boiling tube. Each tube
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has a dif. conc. that goes up in 0.25 intervals from 0 mol/dm3 - 1mol/dm3
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* Leave them for 1h.
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* After
blot them dry to remove any excess water
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* And measure the final mass again
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Explain the photosynthesis rate practical * Place a piece of pondweed into a beaker of water
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* User a light from a set distance from plant
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* Record no. of bubble 3 mins
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* Repeat but w. multiple distances
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How can you test for the presence of lipids in a food sample? * No heating necessary bc ethanol is flammable & it may be dangerous.
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* Food sample first mixed w. ethanol & filtered before adding to distilled
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water
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* IF POSITIVE
IT WILL CHANGE FROM COLOURLESS ---> CLOUDY
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Explain the microbiology practical * Ensure that your hands & workspace are clean by wiping it down with
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disinfectant.
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* Use a permanent marker to divide bottom of plate into section. (keep lid on
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to avoid contamination & add a dot to indicate where to place the disc)
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* Sterilise the bottle of the antisepctic & inoculating loop by turning bunsen
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to blue flame & quickly putting it through the flame
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* Soak paper disc in diff. antisepctics for the same time (incl. a control w.
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water)
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* Use spreader to spread ethanol throughout petri dish
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* Carefully place discs on each dot
slightly opening the lid to reduce
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contamination (always work near bunsen!)
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* Secure lid w/ 2 small pieces of tape (so that anaerobic respiration doesn't
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occur & the E Coli can grow & not other pathogens)
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* Incubate at 25 degrees for 48 hours.
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* Measure zone of inhibition of each one using a ruler.
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How do you test for glucose in food? * Prep. the food by mushing it w. a pestle & mortar
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* Put food in test sample w. BENEDICT'S SOLUTION (around 5cm3). (this is a
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reagant)
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* Put the test tube in a water bath (75oC)
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* If a positive result
it will turn from BLUE ---> ORANGE
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Explain the process behind the microscopy practical. * Use tweezers to peel off the epidermal tissue of the onion.
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* Add a drop of water to a clean side and place the specimen on top
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* Add a drop of iodine to stain it. This is so the cell structures can be
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observed
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* Cover specimen with slip
ensure no air bubbles are present
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* Slide specimen onto stage
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* Ensure lowest powered objective lens is over the stage
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* Look down eyepiece & gradually move stage an use coarse adjustment knob until
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image is roughly in focus
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* To view image w. higher magnification
change lense to a higher power &
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readjust stage if necessary
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* Draw what you see with clear
unbroken lines & magnify if necessary
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How do you test for proteins in a sample? * No heating necessary
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* You prep. the food by mushing it w. a pestle & mortar & pass it through a
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filter
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* Add biuret solution (2cm3)
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* IF POSITIVE BLUE ---> PURPLE
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What is the aim of the photosynthesis practical? Aim: to investigate the efect of light intesite on photosynthesis using an
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aquatic plant.
