core practicals for bio

core practical 1

1. Remove 1 Daphnia with a pipette and place it in a cavity slide under a microscope.

2. Dab around the Daphnia with a tissue to remove the pond water and replace with drops of caffeine solution (e.g. 0.1M).

3. Leave the Daphnia for 5 minutes to acclimatise and then observe & count  (using a counter) the heart rate under the microscope for 30 seconds (multiply number by 2 to calculate beats per minute).

4. Repeat this for measurements across 5 different caffeine concentrations (e.g. 0.2M, 0.3M, 0.4M and 0.5M). Repeats can then be carried out with two other Daphnia.

core practical 2

1. Pipette 1cm³ of 1% blue DCPIP into a conical flask .

2. Fill up a burette with the first type of fruit juice to be used and take a note of the start value.

3. Use the burette to slowly add the fruit juice to the DCPIP drop by drop. Swirl the contents of the conical flask with one hand whilst controlling the tap with the other.

4. Close the tap as soon as the DCPIP loses its blue colour and note the end value.

5. Work out how much volume of the fruit juice was needed to decolourise the DCPIP and note this down in an appropriate table.

6. Repeat this procedure for the other fruit juices available. Repeats can be carried out 2 times to obtain mean results.

core practical 5

1. Place a test tube of 2cm³ HCl (1moldm¯³) into a test tube rack in a 60 ̊C water bath.

2. Cut off 1-2cm of a root tip from garlic root. Put the tip in a watch glass containing 2cm³ of acetic alcohol for at least 12 minutes.

3. Remove the tip and then place into another watch glass containing 5cm³ of ice cold distilled water. Leave for 4-5 mins, and then remove and dry.

4. Place the tip into the heated HCl for 5 minutes then repeat the process again by placing tips back into acetic alcohol etc. Tip: The tips will be very fragile at this point.

5. Transfer 1 tip onto a microscope slide and cut 4-5mm from the growing tip (site of mitosis) and keep it.

6. Gently break up (macerate) the root tip with a mounted needle.

7. Add 1 small drop of orcein ethanoic stain and leave for 2 minutes.

8. Add a coverslip and blot with filter paper.

9. View under a microscope and identify the stages of mitosis.

core practical 7

1. Half fill a test tube with the solution containing all nutrients.

2. Cover the top of the tube with aluminium foil and push down on covering so that there is a well in the centre.

3. Gently push the roots of Mexican Hat plantlet through the hole so it is in the solution below.

4. Repeat steps 1 to 3 with the other 4 solutions.

5. Wrap all tubes in aluminium foil and place them in the test tube rack on a sunny window sill.

6. Leave plantlets for approximately one week.

7. Observe characteristics and growth of the plantlets, comparing each solutions’ effects.

core practical 8

1. The plant material should be left to soak in a bucket of water for about a week in order for the fibres to be easily extracted (retting).

2. Once the fibres have been removed, connect them between 2 clamp stands and gradually add mass in the middle until the fibre snaps. Note the mass required to snap the fibre.

3. Try this again but with individual fibres from different plants and different ways of combining fibres (e.g. twists). You can also compare the tensile strength of the stem to the individual fibres.