Photo AI
Chymosin is an enzyme that causes milk to curdle - Edexcel - GCSE Biology Combined Science - Question 5 - 2021 - Paper 1
Question 5
Chymosin is an enzyme that causes milk to curdle. When milk curdles the proteins in the milk clump together and become solid. (a) As part of an investigation, milk... show full transcript
Worked Solution & Example Answer:Chymosin is an enzyme that causes milk to curdle - Edexcel - GCSE Biology Combined Science - Question 5 - 2021 - Paper 1
Step 1
Step 2
(iii) Explain why the time taken for the milk to curdle decreases from 30°C to 40°C.
Answer
As the temperature increases from 30°C to 40°C, the kinetic energy of the molecules in the milk and the enzyme increases. This results in more frequent collisions between the chymosin enzyme and the milk proteins, which speeds up the curdling process. At higher temperatures, the enzyme also becomes more active, facilitating a faster reaction until it reaches an optimum before potential denaturation occurs.
Step 3
(iii) Explain what the expected result would be if two drops of chymosin were added to the milk at 70°C in the test tube.
Answer
If two drops of chymosin were added to the milk at 70°C, it is expected that the milk would not curdle effectively or at all due to the high temperature. At this temperature, the enzyme may denature, losing its active site structure and functionality, preventing it from catalyzing the curdling reaction.
Step 4
(iv) State why these test tubes containing only milk were used.
Answer
These test tubes containing only milk were used as a control to ensure that any changes observed in the experimental groups can be accurately attributed to the presence of chymosin. This helps to confirm that milk does not curdle at those specific temperatures without the enzyme.
Step 5
(iv) Describe two improvements that could be made to the method of this investigation so that the optimum temperature for chymosin can be found.
Answer
-
Use a range of more precise temperature increments to find the optimum temperature for chymosin, such as 32°C, 34°C, 36°C, and so on, to gather more detailed data.
-
Conduct repeated trials at each temperature to ensure reliability and account for variability in the results.
Step 6
(b) Explain how to genetically modify a bacterial cell to produce chymosin.
Answer
To genetically modify a bacterial cell to produce chymosin, a gene coding for chymosin can be inserted into a plasmid, which is then introduced into the bacterial cell through transformation. The bacteria will then transcribe and translate this gene to produce the chymosin enzyme. Selection markers can be included in the plasmid to easily identify successful modifications.