Biomass - GCSE Biology Definition

What is biomass?

Biomass refers to the total mass of living material in organisms within a specific trophic level, population, or area. It is measured as the dry mass of organic matter, excluding water, which represents the energy available for the next level in a food chain.

Photosynthetic organisms, such as plants and algae, are the producers of biomass for life on Earth. They convert about 1% of light energy into chemical energy stored in their tissues.

Loss of Biomass in Food Chains

As energy moves through trophic levels, biomass decreases significantly. On average, only about 10% of biomass is passed on to the next level due to:

• Egestion: Loss of undigested material.

• Excretion: Elimination of waste products like urea, carbon dioxide, and water.

• Respiration: Energy used for movement, heat, and essential life processes.

This inefficiency in energy transfer limits the number of trophic levels a food chain can support, as there isn’t enough energy to sustain additional levels.

Pyramids of Biomass

The proportions of biomass at each trophic level in a food chain can be represented as a pyramid. These pyramids have a characteristic shape, reflecting the energy losses that occur at each step in the food chain.

Biomass revision resources to ace your exams

You can learn more about biomass in our GCSE biology revision note pages:

• Biomass transfer (AQA GCSE Biology)

• Food pyramids (Edexcel GCSE Biology)

• Pyramids of biomass (OCR Gateway GCSE Biology)

Meet all your GCSE biology revision needs, improve your grades, and boost your confidence using revision resources from Save My Exams. This includes revision notes, videos, flashcards and exam questions with student-friendly mark schemes.

GCSE Biology Revision Resources