OCR Biology Planning Exercise 2008
The effect of the Concentration of Calcium ions on the Coagulation of Milk
Aim/Problem
The aim of this project is to investigate the correlation between the amount of calcium ions in an amount of milk and amount of time it takes for the milk to coagulate.
Hypothesis
I think that the more calcium ions there are in the milk, the faster the milk will coagulate. Also, I think that milk with no calcium ions in will not coagulate at all.
The purpose of milk coagulating is so that when milk is drunk by infant mammals it can coagulate in the stomach so that it is there long enough to be digested. Rennin is a protein-digesting enzyme that curdles milk.[1] Rennin affects milk by breaking peptide bonds. Once these peptide bonds between hydrophobic and hydrophilic groups in the milk are broken, the hydrophobic group would unite together and would form a 3D network to trap the aqueous phase of the milk. The resultant product is calcium phosphocaseinate. [2]
Therefore, I think that when there are fewer calcium ions in the milk, the reaction that produces calcium phosphocaseinate (which appears as coagulation) will take longer because there will be fewer calcium ions to react with.
I predict that a graph plotting concentration of calcium ions against time of first coagulation will look something like this:
Preliminary Investigation
During my preliminary investigation, I conducted parts of the experiment. I first looked at pure milk under the microscope for comparison, and I saw that you could only see a cloudy, white surface with no signs of coagulation. This made a good starting point, so that I could definitely tell when the first signs of coagulation started to appear.
The effect of the Concentration of Calcium ions on the Coagulation of Milk
Aim/Problem
The aim of this project is to investigate the correlation between the amount of calcium ions in an amount of milk and amount of time it takes for the milk to coagulate.
Hypothesis
I think that the more calcium ions there are in the milk, the faster the milk will coagulate. Also, I think that milk with no calcium ions in will not coagulate at all.
The purpose of milk coagulating is so that when milk is drunk by infant mammals it can coagulate in the stomach so that it is there long enough to be digested. Rennin is a protein-digesting enzyme that curdles milk.[1] Rennin affects milk by breaking peptide bonds. Once these peptide bonds between hydrophobic and hydrophilic groups in the milk are broken, the hydrophobic group would unite together and would form a 3D network to trap the aqueous phase of the milk. The resultant product is calcium phosphocaseinate. [2]
Therefore, I think that when there are fewer calcium ions in the milk, the reaction that produces calcium phosphocaseinate (which appears as coagulation) will take longer because there will be fewer calcium ions to react with.
I predict that a graph plotting concentration of calcium ions against time of first coagulation will look something like this:
Preliminary Investigation
During my preliminary investigation, I conducted parts of the experiment. I first looked at pure milk under the microscope for comparison, and I saw that you could only see a cloudy, white surface with no signs of coagulation. This made a good starting point, so that I could definitely tell when the first signs of coagulation started to appear.