Biomass | GCSE Biology

Ecology

Lesson overview

This lesson introduces the core biology idea, the useful equipment and the calculation or data skills used on this page.

Focusfood chains, pyramids and biomass transfer

Time45-60 minutes

EquipmentNotebook, calculator and a pen for labelled diagrams.

Practical linkfeeding relationship and biomass evidence

Maths tagspercentage efficiency, biomass, trophic level and pyramid scale

What you will learn

Describe the key biology ideas behind food chains, pyramids and biomass transfer.
Use precise GCSE command-word language in explanations.
Apply the idea to unfamiliar cells, organisms, data or practical contexts.
Check answers using units, labelled diagrams, observations, calculations or biological evidence where relevant.

Core knowledge

Big idea: Biomass decreases between trophic levels because not all material eaten becomes new biomass in the next organism.
This lesson focuses on food chains, pyramids and biomass transfer. A strong answer explains the biology and points to evidence such as food webs, quadrat data, transects, population graphs and environmental changes.
Producer: an organism that makes its own food, usually by photosynthesis.
Consumer: an organism that gets energy by eating other organisms.
Biomass: the mass of living material.
Use the model as a thinking route: Energy enters through producers -> Biomass is lost between trophic levels -> Efficiency = transferred biomass / previous biomass x 100.
Likely question evidence: food chains, pyramids of biomass, efficiency calculations, trophic levels and feeding relationship diagrams. Use it to justify the explanation, not as decoration.
When numbers or graphs appear, show working with percentage efficiency, biomass, trophic level and pyramid scale and finish by saying what the result means biologically.

Food chains and biomass transfer infographic

Infographic explaining GCSE Biology food chains, trophic levels, pyramids of biomass, biomass losses and efficiency calculations. — Use this visual to follow biomass transfer through trophic levels and calculate transfer efficiency.Download visual

Biomass practice set

Use the worked examples and practice questions on this page as a complete study task: learn the definitions of producer and consumer, summarise the infographic in your own words, then answer the questions using the data, equations and observations given here. Check every answer for percentage efficiency, biomass, trophic level and pyramid scale.

Clear explanation

First secure the anchor idea: food chains, pyramids and biomass transfer. In ordinary language, this means using producer, consumer and biomass to explain what is happening, not just spotting those words in the question.

Next look for the evidence. In this lesson it is likely to come from food chains, pyramids of biomass, efficiency calculations, trophic levels and feeding relationship diagrams.

Then build the answer in order: Energy enters through producers then biomass is lost between trophic levels then efficiency = transferred biomass / previous biomass x 100. This stops the answer becoming a list of disconnected facts.

If the question includes data, use percentage efficiency, biomass, trophic level and pyramid scale. Keep the unit or comparison visible, then link the result back to producer or consumer.

Exam-ready model sentence: Only some biomass is transferred to the next trophic level because material is lost in waste, respiration and uneaten parts.

Worked examples

Biomass: from idea to explanation

Question: Explain food chains, pyramids and biomass transfer using the model.

Start with the idea: Energy enters through producers.

Add the mechanism: biomass is lost between trophic levels.

Finish with the consequence: efficiency = transferred biomass / previous biomass x 100.

Reveal worked answer

Answer: A good answer uses producer (an organism that makes its own food, usually by photosynthesis), consumer (an organism that gets energy by eating other organisms) and biomass (the mass of living material) in one connected explanation. For example: Only some biomass is transferred to the next trophic level because material is lost in waste, respiration and uneaten parts.

Biomass: from evidence to marks

Question: A student has evidence from food chains, pyramids of biomass, efficiency calculations, trophic levels and feeding relationship diagrams. What should their answer include?

Step 1: name the useful evidence rather than writing a general fact about the topic.

Step 2: process any data with percentage efficiency, biomass, trophic level and pyramid scale.

Step 3: explain what the evidence shows about producer and consumer.

Reveal worked answer

Answer: The answer earns marks by joining evidence, method or data to a biological reason. Avoid describing an environmental change without linking it to populations, resources, competition or biodiversity.

Quick checks

Choose an answer, then check your thinking.

1. Which answer would make biomass clearer?

Energy enters through producers and explain it using producer Repeat the topic title without explaining it Ignore the evidence and write a memorised paragraph

2. What should you check before finishing an answer on this lesson?

Whether the answer sounds long enough Whether percentage efficiency, biomass, trophic level and pyramid scale and evidence such as food chains, pyramids of biomass, efficiency calculations, trophic levels and feeding relationship diagrams have been used where needed Whether every keyword from the page has been copied

Practice questions

Question 1

Define producer and use it in a complete sentence about food chains, pyramids and biomass transfer.

Reveal answer and marking guidance

Answer: Producer means an organism that makes its own food, usually by photosynthesis. In food chains, pyramids and biomass transfer, it helps explain energy enters through producers.

Marking: Credit the definition and a sentence that uses the term in the lesson context.

Question 2

Explain the main sequence in Biomass using the infographic.

Reveal answer and marking guidance

Answer: Energy enters through producers -> Biomass is lost between trophic levels -> Efficiency = transferred biomass / previous biomass x 100. A strong answer says why the final step follows from the first two steps.

Marking: Credit the correct order plus a biological link between the steps.

Question 3

A question gives evidence such as food chains, pyramids of biomass, efficiency calculations, trophic levels and feeding relationship diagrams. What should you do with that evidence?

Reveal answer and marking guidance

Answer: Identify the useful observation, method detail or data first. Then use percentage efficiency, biomass, trophic level and pyramid scale where relevant and explain what it shows about producer, consumer or biomass.

Marking: Credit evidence use, relevant data handling and a clear biology explanation.

Question 4

A student writes: 'producer is involved, so the answer is correct.' What detail is missing?

Reveal answer and marking guidance

Answer: Producer means an organism that makes its own food, usually by photosynthesis. A better answer also uses consumer (an organism that gets energy by eating other organisms) and explains the evidence route: Energy enters through producers then biomass is lost between trophic levels. An exam-ready version could be: Only some biomass is transferred to the next trophic level because material is lost in waste, respiration and uneaten parts.

Marking: Credit a precise definition, a second linked term and use of evidence or model steps.

Practice ladder

FluencyRecall the key definition, symbol, structure, equation or observation.

ApplicationApply food chains, pyramids and biomass transfer to unfamiliar organisms, cells, systems, practicals or data.

Practical interpretationUse evidence, method quality, uncertainty or conclusion wording where asked to evaluate.

Maths skillUse units, ratios, graphs and significant figures accurately.

Answers and marking guidance

The exact practice answers are hidden under each question so you can try first. Marks come from using the correct biology model, choosing the right calculation where needed, keeping units with values, labelling diagrams clearly, and explaining changes with precise words such as cells, enzymes, hormones, genes, adaptation, rate, evidence and uncertainty.

Common mistakes

Using producer, consumer or biomass as labels without explaining what they mean.
Forgetting to connect the answer to likely evidence, such as food chains, pyramids of biomass, efficiency calculations, trophic levels and feeding relationship diagrams.
Missing the maths or data habit: percentage efficiency, biomass, trophic level and pyramid scale.
Falling into the common trap of describing an environmental change without linking it to populations, resources, competition or biodiversity.

Extension challenge

Create a focused revision card for food chains, pyramids and biomass transfer: three exact definitions, one model sequence, one evidence detail such as food chains, pyramids of biomass, efficiency calculations, trophic levels and feeding relationship diagrams, one data check using percentage efficiency, biomass, trophic level and pyramid scale, one common misconception, and one exam-ready explanation sentence: Only some biomass is transferred to the next trophic level because material is lost in waste, respiration and uneaten parts.

Reveal answer

Example answer: A complete response names the biology model, uses accurate units or observations, and explains why the evidence supports the conclusion.