# Biology practical - colorimeter

hello,

which colour filter of colorimeter which should I use for measuring the absorbance of milk suspension (which uses trypsin enzymes to break down milk enzyme)
also what should I set my temperature?

I am thinking of 40, 50, 60, 70, 80 degrees Celsius because the optimum temperature for trypsin enzymes to break down milk protein is 65 degrees Celsius?

Original post by BrightBlueStar11
also what should I set my temperature?

I am thinking of 40, 50, 60, 70, 80 degrees Celsius because the optimum temperature for trypsin enzymes to break down milk protein is 65 degrees Celsius?

This says red filter (assuming you're doing this experiment): https://qualifications.pearson.com/content/dam/pdf/A%20Level/biology-b/2015/teaching-and-learning-materials/AS-and-A-level-Biology-B-Core-Practical-1---Reaction-Rate-%28Student,-Teacher,-Technician-Worksheets%29.pdf In a class setting, the tutor will tell you or it will already be set up (or you can ask - they might throw it back to you, ask what you think, tell you to look it up, but asking questions is allowed). Also, if your results are nonsense, you know you've done it wrong. Pay attention also as to whether your are measuring transmission or absorbance.

In terms of temperature range, it depends on source of trypsin, as one would expect human trypsin optimal temperature to be about 37C. You'll also need to consider what equipment you'll have access to - if you can use 3 water baths and a whole class is sharing them, they're likely going to be at 30, 40 and 50 (classrooms tend not to go higher than 50 for safety). You could also do room temperature, if it's stable, or put it in iced water. You just need a sensible range for you to be able to do your analysis. You can always note in your write up that you would have liked to have done more, and why (you can add a reference to a research paper regarding optimum temp, say, if you have one), but equipment wasn't available. Your write up can include how you would've carried out the experiment in an ideal world - as that is really what you're meant to be learning, alongside the realities of actually doing practical work. Knowing the shortcomings and sources of error is really important.
(edited 2 years ago)
Original post by BlueChicken
This says red filter (assuming you're doing this experiment): https://qualifications.pearson.com/content/dam/pdf/A%20Level/biology-b/2015/teaching-and-learning-materials/AS-and-A-level-Biology-B-Core-Practical-1---Reaction-Rate-%28Student,-Teacher,-Technician-Worksheets%29.pdf In a class setting, the tutor will tell you or it will already be set up (or you can ask - they might throw it back to you, ask what you think, tell you to look it up, but asking questions is allowed). Also, if your results are nonsense, you know you've done it wrong. Pay attention also as to whether your are measuring transmission or absorbance.

In terms of temperature range, it depends on source of trypsin, as one would expect human trypsin optimal temperature to be about 37C. You'll also need to consider what equipment you'll have access to - if you can use 3 water baths and a whole class is sharing them, they're likely going to be at 30, 40 and 50 (classrooms tend not to go higher than 50 for safety). You could also do room temperature, if it's stable, or put it in iced water. You just need a sensible range for you to be able to do your analysis. You can always note in your write up that you would have liked to have done more, and why (you can add a reference to a research paper regarding optimum temp, say, if you have one), but equipment wasn't available. Your write up can include how you would've carried out the experiment in an ideal world - as that is really what you're meant to be learning, alongside the realities of actually doing practical work. Knowing the shortcomings and sources of error is really important.

Also, could I ask another question please? I am also planning an experiment for how abiotic factor affects the distribution of a certain species.

So, I am thinking of investigating the effect of trampling (abiotic factor) on the distribution of plantains by investigating two areas (there are a lot of people walking) and untrampled area (where there are less people) Will this experiment work for the A-level Biology?
(edited 2 years ago)
Original post by BrightBlueStar11