A producer is an organism that makes its own food.

Biomass is the mass of living material in one or more organisms.

A trophic level is the position of an organism in a food chain diagram.

A pyramid of biomass is a diagram which shows the biological mass (biomass) of organisms at each trophic level in a food chain diagram.

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.

Transfers of biomass between trophic levels

Biology

Negative human interactions with ecosystems and impacts on biodiversity

Examples of human interactions with ecosystems, including use of peat

Benefits and challenges of maintaining biodiversity

Climate change and biodiversity: changes in the distribution of organisms

Factors affecting human food security, and possible solutions

Pupils learned about biotic and abiotic components of an ecosystem, measuring population size, interdependence and competition in ecosystems, how changes in biotic and abiotic factors affect communities, the cycling of carbon and water, and the role of microorganisms in cycling materials through ecosystems.

This unit explores trophic levels, biomass pyramids, and the efficiency of biomass transfers in ecosystems. It examines human impacts on biodiversity, factors affecting food security, and biotechnological solutions. Emphasis is on evaluating environmental changes and ethical considerations.

Maintaining biodiversity and human impacts

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

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

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

The biomass decreases as you move along the food chain.

The biomass increases as you move along the food chain.

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

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?

Organisms get larger at higher trophic levels.

There are more organisms consuming biomass at higher trophic levels.

Producers are consumed before they make enough biomass.

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?

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

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?

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

It is both a primary and a secondary consumer.

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

Three - mantaray, pufferfish and triggerfish

There are no apex predators in this food web

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

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

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.

The vole is the predator and the moth larva is the prey.

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

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

Potatoes, aphids and swifts will increase.

Potatoes and swifts will increase, whereas aphids will decrease.

Potatoes, aphids and swifts will decrease.

Potatoes and swifts will decrease, whereas aphids will increase.

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?

Starter Quiz

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