1.1.11

Decay

Test yourself on Decay

Test your knowledge with free interactive questions on Seneca — used by over 10 million students.

The Rate of Decay of Biological Material

Biological material in the form of waste products or dead organisms decays as a result of the activity of decomposers. Decomposers are organisms such as worms (which eat the decaying matter) or microorganisms (which use enzymes to break down the organic matter). The rate of the decay process depends on:

Temperature

Temperature

  • High temperature is usually best.
Moisture availability

Moisture availability

  • High moisture availability is usually best.
Oxygen availability

Oxygen availability

  • High oxygen availability is usually best.

Practical - Temperature and Milk Decay

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

Outline

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.
Method

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.
Independent and dependent variable

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
1

Biology

1.1

Practicals

1.1.1Microscope & Bacteria1.1.2Bacteria1.1.3Osmosis Tests1.1.4Osmosis & Food Tests1.1.5Enzymes1.1.6Enzymes 21.1.7Photosynthesis & Plant Responses1.1.8Photosynthesis Experiments1.1.9Reaction Time1.1.10Quadrats1.1.11Decay
2

Chemistry

2.1

Practicals

2.1.1Salts2.1.2Neutralisation2.1.3Titration2.1.4Electrolysis2.1.5Electrolysis 22.1.6Rate of Reaction2.1.7Rate of Reaction 22.1.8Chromatography2.1.9Identifying Gases2.1.10Identifying Gases 22.1.11Identifying Ions2.1.12Carbonates, Halides & Sulfates2.1.13Flame Emission Spectroscopy2.1.14Water Purification2.1.15Water Purification 2
3

Physics

3.1

Practicals

3.1.1Specific Heat Capacity3.1.2Thermal Capacity & Insulation3.1.3Latent Heat3.1.4Resistance & Current3.1.5Resistance & Current 23.1.6Density3.1.7Density 23.1.8Force & Extension - Springs3.1.9Waves - Ripple Tank3.1.10Light3.1.11Light Reflection & Refraction3.1.12Radiation3.1.13Radiation 2

Practice questions on Decay

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

  1. 1
    What are the ideal conditions for decay?True / false
  2. 2
    Which of the following conditions does NOT affect the rate of decay?Multiple choice
  3. 3
    What is the independent variable in an experiment investigating the effect of temperature on the rate of decay of fresh milk by measuring pH change?Multiple choice
  4. 4
    Which substances can be added to speed up the decay of milk?Fill in the list
  5. 5
    What is the name of the indicator used to detect the changing pH of milk?Multiple choice
Answer all questions on Decay

Unlock your full potential with Seneca Premium

  • Unlimited access to 10,000+ open-ended exam questions

  • Mini-mock exams based on your study history

  • Unlock 800+ premium courses & e-books

Get started with Seneca Premium

Quadrats

Salts