| Question | Answer |
| Describe how the effect of caffeine on heart rate in Daphnia can be investigated practically, and discuss whether there are ethical issues in the use of invertebrates | 1.Place Daphnia on cavity slide with caffeine
2.Idea of heart rate determined before
treatment ;
3.Idea that daphnia need to be put into Caffeine and allowed to acclimatise ;
4.Use microscope; to check heartbeat |
| Describe how the effect of caffeine on heart rate in Daphnia can be investigated [2] | 5.Range of caffeine concentrations;
6.Repeats;
7.Water as control / zero caffeine concentration};
8.Control temperature;
9.Similar organisms used;
10.Accurate measurement of DV;
11.Plot results on graph |
| Describe how to investigate the vitamin content of food and drink | 1.DCPIP ;
2.Use of juice ;
3.Idea of titrating juice with DCPIP
4.Colour change e.g. from blue to colourless
5.Use of calibration curve to determine vitamin
C concentration / comparison with standard |
| Describe how to investigate the vitamin content of food and drink [2] | 6.Vitamin C ;
7.Repeated at time intervals
8.Replication ;
9.One controlled variable ;
10.Drawing graph of both sets of results ; |
| Describe how membrane structure can be investigated practically, eg by the effect of alcohol concentration or temperature on membrane permeability | 1.Tissue named e.g. beetroot ;
2.Washing/soaking beetroot thoroughly
3.Waterbath to maintain change temperature
4.Range at least 5{temperatures / alcohol concentrations}
5.Controlled variable named e.g. length of time, size of beetroot |
| Describe how membrane structure can be investigated practically, eg by the effect of alcohol concentration or temperature on membrane permeability [2] | 6.Indication of what is being used to judge permeability colour of solution, absorbance, transmission ;
7.Permeability can be assessed e.g. use of colorimeter, standard solutions ;
8.Repeats / replicates
9.Plot results onto a graph |
| Describe how enzyme concentrations can affect the
rates of reactions and how this can be investigated practically by measuring the initial rate of reaction | Mesure of vol. of oxygen. volume of oxygen
3.Measure the initial rate of reaction
4.CV e.g. age, part of mussel mass,surface area,Vol of hydrogen peroxide, temperature, concentration, pH
6.Repeats |
| Describe the stages of mitosis and how to prepare and stain a root tip squash in order to observe them practically | 1.Use of root tip;
2.Add acid or acetic alcohol
3.Add stain e.g. Toluidine blue
4.Break open tip with (mounted) needle/eq};
5.Mount in stain /acid / water
6.Squash under coverslip;
7.Warm to intensify staining |
| Describe how totipotency can be demonstrated
practically using plant tissue culture techniques | 1.Sample/explants from both(tissues)
2.Aseptic cond.
3.Grow cells in a callus
4.Growth reg.
5.Cells / tissue can differentiate / cells can become whole plants
6.Procedure e.g. agar; leave for a suitable length of time / suitable controlled variable |
| Describe how to determine the tensile strength of plant fibres practically. | 1.Suspending fibres with weights,pulling them with forcemeter
2.Fibres of same diameter,different diameters accounted
3.Fibres of initial length
4.How weights added/forcemeter pulled
5.Measurable endpoint, breaking point stretched to standard length |
| Describe how to determine the tensile strength of plant fibres practically.[2] | 5.Measurable endpoint eg breaking point /
stretched to standard length
6.Repeated readings taken at each {weight / forcemeter reading}
7.Safety procedure eg goggles;fibre
snaps/precaution against weights};
8.Control of {temperature / humidity |
| Describe how to investigate plant mineral deficiencies practically. | 1.3+ range of ion concentrations
2.Repeats(at each concentration)
3. Uniformity of seedlings (e.g. all
from same parent plant, same age, same
original root length)
4.Solution used should contain other
mineral ions / named mineral ions |
| Describe how to investigate plant mineral deficiencies practically. [2] | 5. One other variable maintained / kept
constant (e.g. temp, all run for same length
of time, light intensity, volume of mineral
solution)
6.Mechanism of judging root
{growth /eq} (to measure optimum
concentration) |
| Describe how to investigate the antimicrobial properties of plants. | 1.Filter paper soaked in extract placed on agar plate
2.Bacterial {lawn]
3.Sterile/aseptic e.g.sealing
4.Incubation-24 hours 1 week
5.Incubate temperature 25°C X 37°C human body temp
6.Clear area/inhibition zone
7.Shows no bacteria
8.Suitable con |
