AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Producers are eaten by primary consumers, which in turn may be eaten by…
Full specification wording
Levels of organisation: Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers.
A food chain shows the direction of energy transfer between organisms.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 7 of 12
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A food chain shows the direction of energy transfer between organisms. Producers occupy the first trophic level and are eaten by primary consumers, which are herbivores. Primary consumers may be eaten by secondary consumers, and these in turn may be eaten by tertiary consumers. Each arrow points from the organism being eaten to the organism that eats it, showing the transfer of biomass and energy. The word may is important because not every chain has four levels, and a consumer can occupy different trophic levels in different chains. Energy is lost at each transfer through respiration, movement, excretion and heat, so fewer organisms are usually supported at higher trophic levels.
What earns the marks
- Identifies producers as the first trophic level and primary consumers as the organisms that eat them.
- States that primary consumers may be eaten by secondary consumers, which may be eaten by tertiary consumers.
- Uses arrows correctly to show the direction of energy transfer from eaten organism to eater.
- Explains that energy is lost between trophic levels, limiting the number of levels in a chain.
- Recognises that a consumer may occupy different trophic levels in different food chains.
Common mistakes and how to put them right
Drawing arrows pointing from the consumer to the food it eats.
Put it right: Arrows point from the organism being eaten to the organism that eats it.
Describing energy as being destroyed between trophic levels.
Put it right: Energy is transferred to the surroundings, mainly as heat, and is not destroyed.
Exam tips
- Label each organism with its trophic level when asked to identify producers and consumers.
- Use the phrase energy transfer when explaining what the arrows represent.
- Mention energy losses to explain why food chains rarely have many trophic levels.
Try the lesson
The start of the Levels of organisation: Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers. lesson, made from checked teaching notes for this specification point.
Have a go first
According to the levels of organisation in an ecosystem, which type of organism directly consumes a primary consumer?
Listen
A food chain shows the direction of energy transfer between organisms. Producers occupy the first trophic level and are eaten by primary consumers, which are herbivores. Primary consumers may be eaten by secondary consumers, and these in turn may be eaten by tertiary consumers. Each arrow points from the organism being eaten to the organism that eats it, showing the transfer of biomass and energy. The word may is important because not every chain has four levels, and a consumer can occupy different trophic levels in different chains. Energy is lost at each transfer through respiration, movement, excretion and heat, so fewer organisms are usually supported at higher trophic levels. A strong answer earns marks for these points. Identifies producers as the first trophic level and primary consumers as the organisms that eat them. States that primary consumers may be eaten by secondary consumers, which may be eaten by tertiary consumers. Uses arrows correctly to show the direction of energy transfer from eaten organism to eater. Explains that energy is lost between trophic levels, limiting the number of levels in a chain. A common slip: Drawing arrows pointing from the consumer to the food it eats. Instead, arrows point from the organism being eaten to the organism that eats it. Exam tip: Label each organism with its trophic level when asked to identify producers and consumers.
See it
Key words
Say what each word means before you turn the card.
Food chains
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Trophic levels
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Energy transfer
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Consumers
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See every definition
- Food chains
- A food chain shows the direction of energy transfer between organisms, with each arrow pointing from the organism being eaten to the organism that eats it.
- Trophic levels
- Producers occupy the first trophic level, and a consumer may occupy different trophic levels in different food chains.
- Energy transfer
- Arrows in a food chain show the transfer of biomass and energy, and energy is lost at each transfer through respiration, movement, excretion and heat.
- Consumers
- Primary consumers are herbivores that eat producers, and they may be eaten by secondary consumers, which in turn may be eaten by tertiary consumers.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
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