666satinsdoll666
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Doing a worksheet on effect of temperature on permeability of membranes. First few were fairly easy, then jumped to a hard one, think it's something to do with crystallisation but have no idea, we haven't covered this:

4 Liver cells contain membrane-bound organelles called peroxisomes. These organelles contain catalase, an enzyme that breaks down hydrogen peroxide to release oxygen gas.
A student carried out an investigation on catalase using the following procedure:
• two identical sized cubes were cut from a piece of fresh liver
• one cube was frozen overnight and then defrosted
• the other cube was stored in the refrigerator
• both cubes were returned to room temperature and were placed in separate test tubes containing equal volumes of 2% hydrogen peroxide solution.
The student observed that the cube of liver that had been frozen and defrosted, bubbled significantly more than the cube that had been refrigerated.
Suggest an explanation for this result. (2 marks)

Any ideas?? any help is appreciated! <3
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Becca_390
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(Original post by 666satinsdoll666)
Doing a worksheet on effect of temperature on permeability of membranes. First few were fairly easy, then jumped to a hard one, think it's something to do with crystallisation but have no idea, we haven't covered this:

4 Liver cells contain membrane-bound organelles called peroxisomes. These organelles contain catalase, an enzyme that breaks down hydrogen peroxide to release oxygen gas.
A student carried out an investigation on catalase using the following procedure:
• two identical sized cubes were cut from a piece of fresh liver
• one cube was frozen overnight and then defrosted
• the other cube was stored in the refrigerator
• both cubes were returned to room temperature and were placed in separate test tubes containing equal volumes of 2% hydrogen peroxide solution.
The student observed that the cube of liver that had been frozen and defrosted, bubbled significantly more than the cube that had been refrigerated.
Suggest an explanation for this result. (2 marks)

Any ideas?? any help is appreciated! <3
My answer to this would be that the enzymes, in the cube which was frozen then defrosted again, are working more effectively as they're at a warmer temperature (higher temp increases rate of reaction). Whereas the enzymes of the cube placed in the refrigerator are at a lower temperature so they work slower than the defrosted cube's enzymes (lower temp slower rate of reaction).
As the question doesn't say how long the two cubes have been at room temp, I assumed they weren't at room temp for long hence why I've gone for the temperature argument.

Hope that helps! x
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