7.2.14

Required Practical - Decay

Test yourself

Practical - Temperature & Milk Decay

Investigate the effect of temperature on the rate of decay of fresh milk by measuring pH change.

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Outline

  • The effect of temperature on the rate of decay can be observed using milk.
  • As milk takes a long time to decay, lipase and sodium carbonate are added to speed up the decay.
  • As milk decays, its pH reduces. This can be observed with an indicator called Cresol red.
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Method

  • Use a water bath to heat all of the components to a given temperature.
  • Mix the milk, sodium carbonate and Cresol red. The resulting solution should be purple.
  • Add lipase to the solution and start timing.
  • When the solution turns yellow, stop timing.
  • Repeat using different temperatures.
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Independent and dependent variable

  • The independent variable is the temperature.
  • The dependent variable is the time taken for the solution to turn yellow.

Jump to other topics

1Cell Biology

1.1What's in Cells?

1.2Cell Division

1.3Transport in Cells

2Organisation

2.1Principles of Organisation

2.2Enzymes

2.3Circulatory System

2.4Non-Communicable Diseases

2.5Plant Tissues, Organs & Systems

3Infection & Response

4Bioenergetics

5Homeostasis & Response

5.1Homeostasis

5.2The Human Nervous System

5.3Hormonal Coordination in Humans

5.4Plant Hormones

6Inheritance, Variation & Evolution

7Ecology

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