The food and energy requirements for organisms on Earth are extremely varied. All organisms need energy to survive, some of these organisms get their energy from the sun (like plants with photosynthesis) and others are able to get their energy from consuming other organisms. Organisms living in a particular area and any non-living conditions within the area are together treated as an ecosystem.

Food and Energy in the Food Chain

In all ecosystems, you will find producers. These are organisms which are able to make their own food by photosynthesizing sunlight (see more info on photosynthesis). You will also find consumers within an ecosystem and these are organisms which eat other organisms as a source of energy. This forms the beginning of the food chain.

Producer → Primary Consumer → Secondary Consumer → Tertiary Consumer

Read more about Food and Energy Transfer in Ecosystems

Measuring Biomass & Chemical Energy

Biomass has traditionally been measured in terms of the dry mass of it’s tissue per unit area per unit time. This means you can you find the amount of biomass in some tissue by drying it (leaving it or placing it in an oven or heater until the tissues weight becomes constant).

This tissue sample can be tested for it’s level of chemical energy by burning it, the energy release can be measure in joules (J). It can also be measured by heating up water and the temperature measured, the greater the rise in temperature of the water the more chemical energy the biomass has.

GPP (Gross Primary Production) – total amount of chemical energy converted by producers within an ecosystem using light.

NPP (Net Primary Production) – given that ~50% of GPP is lost as heat (R) the NPP is the remaining chemical energy. This is the energy which will be stored for later use and is the energy which will also be passed up the food chain if not used first.

NPP = GPP – R

Frequently Asked Questions

What is the food chain?

A food chain is a series of interconnected organisms that describes how nutrients and energy move around in an ecosystem. Energy is transferred from one level to another. The producers are present at the lowest level of the food chain while the consumers are present at the highest level. 

Why food chains are important?

Food chains are important as they tell us how different organisms interact with one another in an ecosystem. It helps to understand the complex feeding relationships among the various types of organisms within an ecosystem. They explain how organisms at each level are important for the survival of organisms present at the higher levels.

What is an example of a food chain?

An example of a simple food chain is as follows: 

Grass (produces)⟶Rabbit (Herbivore)⟶Lion(Carnivore)

What is the difference between a food chain and a food web?

A food chain is a linear relationship between the organisms in an ecosystem that tells us about the flow of nutrients and energy from one level to another. On the other hand, a food web represents all the various food chains that can possibly exist in an ecosystem. 

Image Source

https://en.wikipedia.org/wiki/Food_chain#/media/File:Chesapeake_Waterbird_Food_Web.jpg