Food chains
A A sequence (usually shown as a diagram) of feeding relationships between organisms, showing which organisms eat what and the movement of energy through trophic levels. shows the flow of energy and materials from one organism to the next in a A place where plants, animals and microorganisms live.. It begins with a An organism that makes its own food by converting light energy into chemical energy (photosynthesis)..
Producers are green plants which photosynthesise. They use light energy from the sun to convert carbon dioxide from the air and water from the soil into glucose and oxygen. The glucose made can be eaten by other organisms so that they can use it for Chemical reaction that takes place inside living cells, which uses glucose and oxygen to release the energy organisms need to live. Carbon dioxide and water are by-products of respiration. which releases the energy stored in the glucose. This energy can then be used for their life processes.
In this example of a food chain, grass seeds are eaten by voles, and voles are eaten by barn owls.
The arrows between each organism in the chain always point in the direction of energy flow from the food to the feeder.
The position occupied by an organism in a food chain is known as its The position of an organism in a food chain, food web or pyramid.. In the example above:
- the producer (grass seed) occupies the first trophic level
- the The name given to an organism that eats a producer. A herbivore. (vole) is in the second trophic level
- the An organism that obtains its energy by eating the primary consumer. (barn owl) is in the third trophic level
Food chains are rarely longer than four trophic levels as energy is used up or lost at each level.
| Organism | How it gets its energy |
| Producer | Using light energy to produce food by photosynthesis |
| Primary consumer | Eating producers, most are herbivores |
| Herbivore | Eating only plants |
| Secondary consumer | Eating primary consumers, most are carnivores |
| Carnivore | Eating only other animals |
| Tertiary consumer | Eating secondary consumers |
| Omnivore | Consumers which eat both animals and plants, so can occupy more than one trophic level in a food chain |
| Decomposer | Feeding on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces |
| Organism | Producer |
|---|---|
| How it gets its energy | Using light energy to produce food by photosynthesis |
| Organism | Primary consumer |
|---|---|
| How it gets its energy | Eating producers, most are herbivores |
| Organism | Herbivore |
|---|---|
| How it gets its energy | Eating only plants |
| Organism | Secondary consumer |
|---|---|
| How it gets its energy | Eating primary consumers, most are carnivores |
| Organism | Carnivore |
|---|---|
| How it gets its energy | Eating only other animals |
| Organism | Tertiary consumer |
|---|---|
| How it gets its energy | Eating secondary consumers |
| Organism | Omnivore |
|---|---|
| How it gets its energy | Consumers which eat both animals and plants, so can occupy more than one trophic level in a food chain |
| Organism | Decomposer |
|---|---|
| How it gets its energy | Feeding on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces |
Question
A vole gets its energy from eating grass, but also eats insects. This makes it both a primary and secondary consumer. Which term from the table above could be used to describe the vole?
Omnivore.