All food chains start with a producer that makes the biomass that is transferred to consumers in higher trophic levels.
Not all biomass from a trophic level is passed to the next one (due to respiration, uneaten parts, egestion, excretion).
Pyramids of biomass are scaled diagrams that can be used to show the amount of biomass present at each trophic level.
% efficiency of biomass transfer = (biomass in higher trophic level ÷ biomass in lower trophic level) × 100
How efficiency of biomass transfer affects the number of organisms in higher trophic levels.

Common misconception

A misconception that is often seen is that there is a build up of biomass along a food chain.

The lesson outlines how biomass is actually lost between trophic levels through life processes.

Keywords

Producer - A producer is an organism that makes its own food.
Biomass - Biomass is the mass of living material in one or more organisms.
Trophic level - A trophic level is the position of an organism in a food chain diagram.
Pyramid of biomass - A pyramid of biomass is a diagram which shows the biological mass (biomass) of organisms at each trophic level in a food chain diagram.
Efficiency - The efficiency is how much of something is transferred compared to how much is available, e.g. how much biomass is transferred to a consumer compared to how much is available.

This lesson is a good opportunity to highlight that the majority of the mass of organisms (up to 90% in some species) is made up of water. This fact can be used to illustrate why water is such an important molecule for life to exist.

Teacher tip

Equipment

None required.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.

Look at the food chain diagram below. Name the producer.

Correct answer: algae

shrimp

cod

seal

polar bear

Q2.

Look at the food web diagram. What type of organism is the triggerfish?

It is a primary consumer.

It is a producer.

It is a secondary consumer.

Correct answer: It is both a primary and a secondary consumer.

It is a tertiary consumer.

Q3.

How many apex predators are there in this food web and what organisms are they?

One - tiger shark

Two - phytoplankton and seaweed

Correct answer: Two - tiger shark and tuna

Three - mantaray, pufferfish and triggerfish

There are no apex predators in this food web

Q4.

What word describes the amount of living material found in one or more organisms?

Correct Answer: biomass

Q5.

Which option correctly matches the predator to the prey, based on the food web below?

The owl is the predator and the ladybird is the prey.

The spider is the predator and the aphid is the prey.

The stoat is the predator and the bramble is the prey.

Correct answer: The vole is the predator and the moth larva is the prey.

The aphid is the predator and the bramble is the prey.

Q6.

The diagram below shows a food chain. If the number of ladybirds decreases due to disease, what will happen to the numbers of other organisms in the food chain?

Potatoes, aphids and swifts will increase.

Potatoes and swifts will increase, whereas aphids will decrease.

Potatoes, aphids and swifts will decrease.

Correct answer: Potatoes and swifts will decrease, whereas aphids will increase.

Q1 UYSEG

Exit quiz

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6 Questions

Q1.

Look at the food chain diagram below. Match the organism to the correct trophic level it occupies.

Correct Answer:algae,producer

producer

Correct Answer:shrimp,primary consumer

primary consumer

Correct Answer:cod,secondary consumer

secondary consumer

Correct Answer:seal,tertiary consumer

tertiary consumer

Correct Answer:polar bear,quaternary consumer

quaternary consumer

Q2.

Look at the pyramid of biomass. What can you tell from the pyramid of biomass?

The number of organisms increases as you move along the food chain.

The number of organisms decreases as you move along the food chain.

Correct answer: The biomass decreases as you move along the food chain.

The biomass increases as you move along the food chain.

Q3.

In food chains, biomass can be lost between different trophic levels. One example is when food that is eaten is not digested. The undigested food is released from the body. What is the release called?

excretion

indigestion

Correct answer: egestion

decomposition

Q4.

Food chains show how food (biomass) is transferred from one organism to another. Most food chains contain five trophic levels or less. Why are food chains not longer than this?

Organisms get larger at higher trophic levels.

Correct answer: Biomass is lost at each trophic level.

There are more organisms consuming biomass at higher trophic levels.

Producers are consumed before they make enough biomass.

Q5.

How much of something (e.g. biomass) is transferred compared to how much is available is known as what?

Correct Answer: efficiency, efficient

Q6.

Look at the table of biomasses of organisms that could be found in a food chain diagram. What is the approximate percentage efficiency of biomass transfer between each trophic level?

100%

50%

Correct answer: 10%

0.1%