Core Practicals Flashcards
Describe the procedure used to test the effect of caffeine on heart rate on daphnia
Remove 1 daphnia and place it on a caviety slide
Remove pond water and replace with distilled water m
Then after time count and observe the heart rate *2 to work out heart rate repeat with 2 more daphnia
Repeat the steps again this time using a small concentration of caffeine solution(increaseing the concentration each time)
Repeat the experiment 3 times for 3 concentrations to obtain average
State some control variables in the daphnia experiment and in some cases state how they could be controlled
Temperature
Same species of daphnia
Time(using a stopwatch)
Volume of caffeine solutions(can be obtain by using a pipette
Explain why daphnia is used in the experiment on heart rate
They are simple organisms so less likely to feel pain
They are transparent so we can see the heart beat
Describe the procedure involved in measuring the content of vitamin c in fruit juice
Pipette 1cm of blue DCPIP into a test tube
using a burette or pippette add 1% of vitamin C solution drop by drop,shake the tube gently after each drop
Continue to do so until the blue colour just starts to disappear
Record the volume of solution needed to decolourise the DCPIP
Repeat twice more in order to calculate the mean result,repeat the procedure with different fruit juices
State some control variables in the measuring of the content of vitamin C solution
Temperature
Concentration of DCPIP solution
Shake each tube same number of times
Same end point In which blue colour disappears
Describe the procedure involved in measuring the effect of temperature on cell memebranes
Using a cork borer and knife cut pieces of beetroot into 1cm length of cylinders let them dry
Place 8 boiling tubes of distilled water into 8 water baths with different temperatures
Once at temperature add a piece of beetroot to each and leave for 30 mins then remove the beetroot and let the dye disperse
Set the colorimeter to absorbance on blue and green filter and calibrate using distilled water in a cuvette
Then add 2cm3 of beetroot solution from the first temp and place it in a corvette and place it in the colorimeter and read the absorbance
Repeat procedure twice more and obtain an average
State some control variables in experimenting the effect of Temperature on membranes
Time left in water
Volume of distilled water
Size of beetroot
Describe the procedure used in investigating the effect of changing enzyme concentration on rate of reaction
Using distilled water make up different concentrations of enzymes
Set up a water bath for temperature to keep constant
Place 1 test tube of 5cm3 of casein dilution into water bath alonsise a second test tube containing 2cm of 0.2 trypsin
Allow to acclimatise for 3 mins so they reach the same temperature then add trypsin to casein to start the stop clock time how long it takes for casein solution to turn transparent(mark a X on other side of tube when visible stop clock)
Repeat twice more then repeat for other concentrations
State some control variables in the effect of enzyme concentration on rate of reaction
Temperature
Ph
Volume of enzyme and substrate
Condensation of substrate
In the experiment that’s investigating change in enzyme concentration of rate if reaction state why different syntinges are used
Different syringes are used to prevent cross contamination
Describe the procedure when observing mitosis
Place a test tube of 2cm3 1m HCL into 60 degree waterbath
Cut off 1-2cm of root tip from a garlic root and place it in a watch glass containing 2cm3 of acetic alcohol for at least 12mins
Remove then place in another water glass containing ice cold distilled water
Leave for 4-5 mins then remove and dry and place into heated HCL for 5 mins and then repeat the process all over again
Transfer one tip to a microscope slide gently macerate with a needle add one small drop or precinct ethanoic stain and leave for 2 mins
Add a coverslip and blot with filter paper and view under a microscope and identify each stage of mitosis
Describe a procedure to investigate the strength of plants fibres
Leave the plant material in a bucket of water for time
Then extract the fibres
Connect one fibre between two clamp stands and gradually add mass in the middle until the fibre snaps repeat to maintain a mean
Repeat the experiment on other species
State control variable in investigating the strength of plant fibres
Length of fibre
Age of fibre
Size of individual mass
Describe the procedures investigating plant mineral deficiencies
Fill half a tube with all nutrients present solution cover the tube with foil and push down on covering so there is well in the centre
Gently push the geranium stem into the solution below
Repeat with solutions lacking in nitrogen,potassium,magnesium,phosphate,calcium and lacking in all solutions
Wrap all in aluminium foil and place on a sunny window still and observe regularly
State some control variables in the investigation of plant material deficiencies
Volume of mineral solution
Plant species
Size of container
Amount of light revived
Describe a procedure for investigating the effect of Garlic and mint on bacterial growth
Make a plant extract by crushing 3G of plant material with 10cm industrial denatured alcohol shake occasionally for 10 mins
Pipette 0.1cm3 of extract into sterile paper disc
Allow to dry on sterile Petri dish
Label agar plat with date and split into 4 sections 1 for each type of plant extract place a disc of each extract into each quadrant of the agar plate
Close the tape with hazard tape
Leave to incubate over night and observe zone of inhibitions
Repeat 3 times
The larger the zone the more effective it is
State some control variable in investigating the effect of garlic and mint on bacterial growth
Same volume of plant material on each disc
Concentration of plant material
Lawn of bacteria on Petri dish
Contamination of Petri dish by other microbes
State the role of distilled water in investigating the effect of garlic and mint bacterial growth
It acts as a control
Describe how you would investigate the distribution of a plant/crop in a field
Using a tape measure mark out 10 by 10m in to different areas of the field
Using random number generator select coordinates in the area and at the coordinates place a quadrant and calculate the percentage cover in that area repeat 20 times in each area
Make sure variables like light,temperature,soil are controlled
Furthermore repeat the experiment again and obtain an average result from percentage cover in each area
Use a statiscal test to back up your findings
Describe a practical to test the effect of Tempe the hatching success of bribe shrimp
Decide on a range of temperatures from 5 to 35 to be tested
Place 2g of sea salt into 100cm beaker and add 100 cm of de chlorinated water and stir until the salt has completely dissolved
Label the beaker with sea salt and the temperature at which it will be incubated
Place a tiny pinch of egg cysts onto a large sheet of white paper,wet a piece of graph paper and use it to pick up 40 eggs from the sheet.
Put the paper with 40 eggs into a beaker upside down after 3 mins use forceps to gently remove the paper and make sure the eggs have washed off into the water
Incubate the beakers at different temperatures, the next day count the number of hatched lavre in each beaker
And record the number of larvae that have successor hatched at each temperature
To test for correlation between them use spearmans rank
State control variables in the brine shrimp experiment
Ph Light intensity Salt content Oxygen concentration Presence of chlorine from Tap water
In the brine shrimp practical state how you would count the number of hatched larvae
Place a bright light next to the beaker and any larvae will swim towards the light
Describe a practical used to test the effects of different antibiotics on bacteria
First use aseptic techniques such as using placing the forceps in a Bunsen after every use
Prepare an agar plate that’s seeded with bacteria
Label the Petri dish on the base at the edge with the type of bacterium it’s inoculated with
Flame the forceps and use them to pick up an antibiotic disc and place it in the Petri dish and use a tape to seal the Petri dish shut
Keep it at 30 for 48 hours after incubation and look at the zones of inhibition around each antibiotic
The larger zone the more effective the antibiotic against that species
Describe a procedure to help identify plant stems in a section
Use a scalpel cut a cross section of the stem and cut the sections as thinly as possible
Use tweezers to remove and place in water
Transfer each section to a dish containing a stain (toluidine blue and leave for a minute)Tbo stains lignin blue green so we can see the position of xylem and scelrencyma
The rest of the phloem remains purple
In the mitosis practical state the reason For the use of HCL
To break up middle lamela so it’s easier to macerate
State why the root tip is used in observing mitosis
As it’s the site of mitosis in a plant
