all biology practicals

IV: caffeine                                                                                                                                         DV: heart rate of daphnia (BPM)                                                                                                           CV: temperature, volume and concentration of solution, time to acclimatise, from same pond.    

Ethics: return them to their natural habitats, storing them in simular env to that of their normal habitats, dont use excessive amounts of caffeine and mimise stress. 

Method: 

• remove daphnia with a pipette, place on cavity slide with wool (stays still)
• dab around to remove pondwater and imediately add the IV
• leave to acclimatise, the observe the daphnias heart and count the BPM under microscope.
• repeat with different caffeine concentration, control pondwater.

IV: type of fruit juice.                                                                                                                              DV: volume of juice require to decolourise the DCPIP.                                                                          CV: temperature, concentration of DCPIP, shake tube same number of times, same end point colour.                                                                                                                                                    

Method:

• pipette 1cm3 of 1% DCPIP into conical flask.
• fill up burette with fruit juice and take note of start value.
• use burette to slowly add fruit juice, swirl.
• close when DCPIP looses its blue colour.
• work out how much juie needed needed to decolourise.
• repeat with other fruit juices and repeat each of the types.

IV: temperature of water in the water bath.                                                                                       DV: percentage of light transmission through resulting solution                                                       CV:  volume of water, time left in water, size od beetroot piece, colouromiter used, volume of beetroot solution added to the cuvette

Method:

• use a cork borer to cut equal cylinders, place in beaker of distilled water overnight.
• wash and blot dry.
• fill 8 boiling tubes with 10cm3 of distilled water and place into water baths ( 0-70 degrees)
• once at temp add the pieces of beetroot and leave for 30 mins
• remove with forceps and shake to disperse the dye.
• set colouromiter to % absorbance, calibrate using water  and then start with smallest temp.
• place all solutions in colourometre seperately to get % absorbance.

IV: protase concentration                                                                                                                     DV: time taken for enzyme to break down substrate.                                                                       CV: temperature, volume of enzyme solution, volume of substrate, concentration of substrate.

Method: 

• set up a water bath to keep temperature constant.
• one test tube containing 5cm3 of casein solution (put x underneath) , second with 2cm3 of trypsin.
• allow to acclimatise for 3 mins
• add test tubes together and record how long it takes for casein to turn transparent (to see thre 'X' underneath.
• repeat 2 times and repeat for other concentratiosn 

Method:

• put test tube of 2cm3 HCL into rack in 60 degrees water bath
• cut off 1-2 cm of a garlic root tip, put on watch glass of 2cm3 acetic alcohol for 12 mins.
•  remove and put on another watch glass containing 5cm3 ice cold distilled water leave for 5 mins 
• put into heated HCL for 5 mins and repeat process by placing in a.a ect.
• transfer 1 onto microscoope slide and cut out 5 mm from growing tip.
• macerate root tip with mounted needle.
• add one drop of orcein ethanoic stain and leave for 2 mins
• and coverslip and blot
• view under microscope and observe stages of mitosis.

Method: 

• place piece of tinned thubarb on watch glass, use forceps to pick out two vascular bundles and place on microscope slide 
• use mounted needle to prize bundle apart, and cover with a drop of methylene blue, leave for 5 mins 
• blot with filter paper, add a drop of dilute glycerol on the fibres and mount under cover slip.
• examine under different magnifications
• look for vascular bundles amongst seperated tissues.

IV: mineral present.                                                                                                                                 DV: physical characteristics of the plant.                                                                                              CV: volue of mineral solution used, smae species of plant, size of plant, amount of light received, same time growing.

Method: 

• half fill test tube with solution of all nutrients
• cover top of tube with aliminium foil and push down so that there is a well in the cente.
• push roots of plantlet through hole so its in the solution below.
• repeat with other solutions.
• wrap all tubes in aliminium foil and place on a rack on sunny window sill.
• leave for one week.
• obs characteristics and growth of plantlets comparing the solution effects.

IV: type of of fibre used                                                                                                                     DV: amount of mass added before the fibre snaps.                                                                               CV: temperature of the surroundings, length of fibre, size of each individual mass.

Method 

• extract the fibres from a celery stick.
• once removed, connect them between 2 clamp stands and gradully add masses in middle until the fibre snaps.
• try this again with different p;ant fibres, varing the ways of combining fibres e.g. twisting them, you can also compare the tensile strength of the stem to the individual fibres.

IV: substance that is being tested for antimicrobial properties.                                                          DV: zone of inhibition (cm2)

control: conc of plant material, type of bacteria (e.coli), temp of cultures, ph of medium.

method:

• crush 3g garlic with P&M and 10cm3 denatures alcohol to mixture, shake for 10 mins.
• repeat using mint.
• pipette 0.1cm3 of garlic onto paper discs, repear for garlic.
• use sterile forcepts to place onto petri dish. close with hazards tape so no o2 and no built up anaerobic bacteria.
• leave overnight
• open and use a ruler to measure zones.

ISLE OF ARRAN

Carry out a study on the ecology of a habitat, such as using quadrats and transects to determine distribution and abundance of organisms, and measuring abiotic factors appropriate to the habitat.  random sampling,systematic sampling

This involves measuring the abundance of an organism and can be done in a number of different ways:

• Density – presence of organisms per quadrat
• Frequency – percentage of quadrat squares containing organism
• Percentage cover – percentage of ground covered with organism in a quadrat (usually for plants)
• Pitfall trap – to collect invertebrates
• Sweep net – to collect invertebrates in long grasses
• Pooter – to collect invertebrates into a container
• Tullgren funnel – to collect organisms from soil or leaf litter
• Baermann funnel – to collect living organisms from water

IV: light intesnsity reaching the chloroplast samples.                                                                       DV: amount of DCPIP  reduced.                                                                                                Controls: same species of plant, amount of buffer to solutions (5cm3), amount of DCPIP, time, ph used 

method:

• grind 5g spinach with with 10cm3 ice cold 0.5m sucrose solution using P&M.
• strain into centrifuge tube, centrifugre for 5 mins, decant the supernatant into tube anf centrifuge for 10 mins.
• pipette of supernatant and discard. use sediment and 2cm3 ice cold sucrose solution and mix.
• add 20 cm ice cold ph 7 buffer solution and mix. Add 5cm3 solution to tube A and B.
• A under lamp , B in a cupboard.
• obs tube a until blue of DCPIP has disapeared. remove tube B from cupboards and compare.

IV: temp of each enzyme solution.       DV: time taken to turn pink

control: volume of enzyme solution, volume of milk, sodium carbonate, colour of solution.

method:

• set up water baths 10-50 degrees. put a beaker of lipase with 2cm3 syringe in.
• label with temp being investigated. Add 5 drops of phenolphthalein into each tube.
• 5cm3 of milk and add to tube, and 7cm of sodium carbonate 2= solution pink.
• place thermotetre in test tube.
• test tube in water bath and wait to acclimitise.
• remove thermometre. replace with glass rod.
• measure 1cm3 lipase from beaker. add lipase to test tube.
• stir until solustion looses pink colour. (measure time).

IV: temperature of each sample DV: number of hatched shrimps

control: sea salt used, volume of water used, brine shrimp eggs, light intensity, time

Method:

• set up water baths, 10 ,15, 20, 25, 30.
• 2g salt into 100cm3 beaker, add 100cm3 dechlorinated water, stir until dissolved. (label )
• place eggs onto white paper and dab wet graph paper to pick up approx 40.
• put eggs into beakers and remove paper.
• imcubate at apropriate temps controlling light.
• next day count the number of larvae hatched
• catch and put in beaker of salt water, record number that have successfuly hatched at each temp.

Method:

1. Mix the DNA sample with restriction endonuclease enzymes and a loading dye in a beaker.
2. Prepare the agar and pour it into the electrophoresis mould.
3. Once set, fill the electrophoresis tank with a buffer solution.
4. Use a micropipette to load the restriction ladder into the first well and then the DNA samples cut with restriction enzymes into the other wells.
5. Connect the tank to an electrical supply, turn it on and leave until the dye has moved to the opposite end of the gel tank.
6. Switch it off and disconnect the electrical supply.
7. Carefully remove the gel from the tank and view the samples under UV light. You may also take a picture.

IV: tybe of antibiotic.   DV: zone of inhibition 

control: conc of antibiotic, type of bacteria,  contaminination of culture, tem of culture, PH.

method:

1. Label 2 Petri dishes for the antibiotic mast ring and the distilled water control – include the date.
2. Use the sterile forceps to place the mast ring/paper discs of distilled water onto their corresponding Petri dish. Close each dish and seal with hazard tape. Make sure that a small gap is left so that oxygen can enter and there is no build-up of anaerobic bacteria.
3. Leave the cultures to incubate at 25°C for 24 hours.
4. Open each Petri dish and use a ruler to work out the zone of inhibition for each paper disc/mast ring section.