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Year 10
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Higher

Factors affecting the rate of decomposition

I can explain why some factors affect the rate of decomposition by microorganisms.

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Share activities with pupils
New
New
Year 10
OCR
Higher

Factors affecting the rate of decomposition

I can explain why some factors affect the rate of decomposition by microorganisms.

Download all resources
Share activities with pupils

These resources will be removed by end of Summer Term 2025.

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Lesson details

Key learning points

  1. Microorganisms use enzymes to decompose biological material.
  2. The rate of decomposition is affected by temperature, which affects the rate of enzyme-controlled reactions.
  3. The rate of decomposition is affected by the availability of water, which microorganisms need to survive.
  4. The rate of decomposition is affected by the availability of oxygen to aerobic and anaerobic microorganisms.

Keywords

  • Microorganism - A microorganism is an organism that can only be seen using a microscope.

  • Decomposer - A decomposer is an organism that feeds on the remains of other living organisms (organic matter).

  • Enzyme - A protein which acts as a biological catalyst. This speeds up a reaction without being used up.

  • Rate - The rate is how quickly something takes place. The rate of a reaction is a measure of how much change occurs per unit of time.

  • Aerobic - Aerobic means in the presence of oxygen.

Common misconception

Research has found that pupils generally do not appreciate the important roles of microorganisms in decomposition and the recycling of elements. Many associate microorganisms only with disease.

The lesson outlines the factors that are important in recycling of elements but also that microorganisms are the natural cleaners of the environment.


To help you plan your year 10 biology lesson on: Factors affecting the rate of decomposition, download all teaching resources for free and adapt to suit your pupils' needs...

This lesson is a great opportunity to illustrate that not all microorganisms are harmful. Some, such as decomposers, are helpful and even essential for our survival.
Teacher tip

Equipment

None required.

Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Prior knowledge starter quiz

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6 Questions

Q1.
What piece of equipment might you use to observe a microorganism?

telescope
Correct answer: microscope
binoculars
periscope
magnifying glass

Q2.
Which of the following organisms are examples of decomposers?

Correct answer: bacteria
dragonflies
Correct answer: fungi
blackbirds
hedgehogs

Q3.
Biogas is a product of decomposition. It is formed by microorganisms that decompose organic waste under what sort of conditions?

When there is lots of oxygen present.
Correct answer: When there is little or no oxygen present.
When there are high temperatures.
When there are very low temperatures.

Q4.
Decomposers carry out two important jobs in an ecosystem. What are they?

They supply oxygen for plants to use in photosynthesis.
Correct answer: They keep the ecosystem clean by breaking down dead organic matter.
They provide herbivores with the food that they need.
They provide food for all the consumers.
Correct answer: They recycle important elements that are used by producers for healthy growth.

Q5.
Compost is a product made when dead plant material decomposes. Why is compost useful for gardeners to add to their soil?

Correct answer: The compost contains recycled minerals that help plants to grow.
The compost releases nitrogen into the air for plants to use.
The compost makes new minerals that help plants to grow.
The compost helps to keep animals off the garden.

Q6.
When does anaerobic decomposition take place?

When bacteria and fungi break down organic matter in very dry soils.
When plants compete with decomposers for food.
When plants make their own food.
When bacteria and fungi produce energy from food to carry out life processes.
Correct answer: When bacteria and fungi break down organic matter in waterlogged soils.

Assessment exit quiz

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6 Questions

Q1.
Which factors affect the rate of decomposition?

Correct answer: moisture levels
carbon dioxide availability
Correct answer: oxygen availability
light intensity
Correct answer: temperature

Q2.
Which of the following is an example of a biological catalyst?

decomposer
Correct answer: enzyme
manure
compost
detritivore

Q3.
Temperature affects the rate of decomposition. Which of the following statements is correct?

As the temperature increases, the rate of decomposition increases.
As the temperature decreases, the rate of decomposition increases.
Correct answer: The rate of decomposition increases with temperature until enzymes denature.
As the temperature increases, the rate of decomposition stays the same.

Q4.
Increased oxygen levels causes ...

decomposition to stop.
the rate of decomposition to slow down.
the rate of decomposition to stay the same.
Correct answer: the rate of decomposition to increase.

Q5.
When there is lots of oxygen present, the conditions are said to be .

Correct Answer: aerobic

Q6.
Why might stirring / turning over the contents of a compost bin increase the rate at which decomposition takes place?

An image in a quiz
Stirring the contents will release heat from the compost.
Stirring the compost will help to release moisture to the air.
Correct answer: Stirring the compost will help to provide more oxygen to decomposers.
Stirring the contents will make the compost wet.