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the effect of calcium ions on the coagulation of milk.

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AS Biology Planning Exercise Purpose This plan plans an experiment that aims to find out about the effect of calcium ions on the coagulation of milk. Apparatus and materials * 6 beakers (50cm�) * thermostatic water bath * glass slide * marker pen * stop watch * Sodium citrate solution (3%) * rennin solution * calcium chloride solution * milk * 2 syringes; one 1cm and one 10 cm * stirring rod * pipette * safety glasses Risk assessment and safety precautions * Be careful with warm water and chemicals * Wear safety goggles during the experiment to because rennin solution irritates eyes Method Get the 6 beakers and use the marker pen to label them A-F then fill all the beakers with 10cm� of milk using the 10cm� syringes like shown below in FIG. ...read more.


Restart the stop watch and put the glass slide in the beaker. Pull the slide out every 10 seconds until a fleck occurs on the slide then record the reading of the stop watch in results table. Continue to do the same with the beakers B-F making sure the conditions e.g. same 10 second time interval are all the Same so the results will be accurate. Afterwards Convert the times taken for first observation of coagulation into relative rates of coagulation/fleck formulation by diving 1000 by the time taken in seconds for each tube as follows: Relative rate of fleck formation = 1000 t t= time taken for fleck to appear. Add the results of your calculations to your table. Then use the results form your results table to plot a graph showing the distribution of the relative rate of fleck formation like shown below. ...read more.


then the milk won't coagulate because there will be no calcium ions to activate the rennin. Remarks All enzymes have properties of proteins because they are protein molecules so they are denatured at high temps. I decided to have the water bath at 35�C so the enzyme won't be denatured and because rennin is an enzyme and most enzymes have an optimum temperature of about 35�-40�C. Temperature had to be a controlled variable to keep the test fair because it affects the rate of enzyme activity. Enzyme concentration also had to be controlled to make the test fair because enzyme concentration would affect the rate of coagulation. To see how calcium ions act as a rennin activator the concentration of calcium ions had to be varied that is why I chose the concentration of calcium ions as my independent variable. The plan could be improved my doing repeated testing this would make the results more accurate. ...read more.

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3 star(s)

This report has some good section but is lacking detail.
1. The method section is well written and structured.
2. The prediction and remarks sections show promise.
3. The report needs to be restructured so that the information is in the correct place.
4. The report lacks detail in many sections and the language used is inconsistent.
5. The information needs to be referenced to indicate the source.
***(3 stars)

Marked by teacher Luke Smithen 08/05/2013

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