This question is about the decay of milk. 1. Name two types of microorganism that cause decay. 2. Cows' milk is pH 6.6. As milk decays, lipids in the milk are broken down. One of the products of the breakdown of lipids causes the pH of milk to decrease. Name the product that causes the pH to decrease. 3. Give one way the pH can be measured. 4. Give two control variables the student should have used in this investigation. 5. Which type of milk stays fresh the longest at 10 °C? 6. Describe the effect of temperature on the time taken for goats' milk to reach pH 5. Use data from Figure 1 in your answer. 7. The time taken for cows' milk to reach pH 5 at 10 °C is less than the time taken for goats' milk to reach pH 5.

GCSE AQA Biology Communicable Diseases: This question is about the decay

This question is about the decay of milk - AQA - GCSE Biology - Question 1 - 2020 - Paper 1

Question 1

This question is about the decay of milk. 1. Name two types of microorganism that cause decay. 2. Cows' milk is pH 6.6. As milk decays, lipids in the milk are brok... show full transcript

Worked Solution & Example Answer:This question is about the decay of milk - AQA - GCSE Biology - Question 1 - 2020 - Paper 1

Step 1

Name two types of microorganism that cause decay.

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Answer

Bacteria
Fungi

Step 2

Name the product that causes the pH to decrease.

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Answer

Fatty acids, produced from the breakdown of lipids.

Step 3

Give one way the pH can be measured.

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101 rated

Answer

Using a pH meter.

Step 4

Give two control variables the student should have used in this investigation.

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Answer

Volume of milk used
Temperature during the investigation

Step 5

Which type of milk stays fresh the longest at 10 °C?

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Answer

Almond milk

Step 6

Describe the effect of temperature on the time taken for goats' milk to reach pH 5.

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Answer

As the temperature increases up to 15 °C, the time taken for goats' milk to reach pH 5 decreases. However, above 15 °C, the time taken remains constant.

Step 7

The time taken for cows' milk to reach pH 5 at 10 °C is less than the time taken for goats' milk to reach pH 5.

96%

114 rated

Answer

This indicates that cows' milk decays faster than goats' milk under the same temperature conditions.

This question is about the decay of milk - AQA - GCSE Biology - Question 1 - 2020 - Paper 1

Worked Solution & Example Answer:This question is about the decay of milk - AQA - GCSE Biology - Question 1 - 2020 - Paper 1

Name two types of microorganism that cause decay.

Name the product that causes the pH to decrease.

Give one way the pH can be measured.

Give two control variables the student should have used in this investigation.

Which type of milk stays fresh the longest at 10 °C?

Describe the effect of temperature on the time taken for goats' milk to reach pH 5.

The time taken for cows' milk to reach pH 5 at 10 °C is less than the time taken for goats' milk to reach pH 5.

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