Trophic levels in an ecosystem

• Trophic levels are shown in food chains, with each stage being a trophic level.
• Biomass is a measure of the total mass of living material in each trophic level.
• Pyramids of biomass, transfer of biomass, and calculating efficiency of biomass transfers are all aspects of trophic levels.
• A food chain is a sequence of feeding relationships between organisms, showing which organisms eat what and the movement of energy through trophic levels.
• An ecosystem is the living organisms in a particular area, together with the non-living components of the environment.
• A food web is a collection of food chains in an ecosystem.
• Trophic levels are the stages in a food chain or web.
• The position of an organism in a food chain, food web or pyramid is referred to as its trophic level.
• The arrows in a food chain or web show the transfer of biomass from one trophic level to another.
• A producer is an organism that begins food chains by making energy from carbon dioxide and water.
• Photosynthesis is a chemical process used by plants to make glucose and oxygen from carbon dioxide and water, using light energy.
• Oxygen is produced as a by-product of photosynthesis.
• Scavengers feed on dead animals, examples include crows, vultures and hyenas.
• The final level in a food chain is perch, also known as the apex predator.
• Producers are green plants which make glucose during photosynthesis.
• Algae are the producers in the food chain above.
• Decomposers feed on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces.
• Organisms at the top of food chains have no predators.
• Decomposers include bacteria and fungi which breakdown dead plant and animal matter.
• Decomposers secrete enzymes on the surface of the dead organisms to break the down and then absorb the digested, smaller food molecules.
• Decomposers are organisms which eat dead organisms, fallen leaves, animal droppings, etc., and break them down into simpler materials.
• There may be additional carnivorous consumers at the top of food chains, which are referred to as tertiary and quaternary consumers.
• Prey are the animals that predators feed on.
• Secondary consumers usually eat animal material and are carnivores, examples include cats, dogs and lions.
• Predators kill for food and are either secondary or tertiary consumers.
• Primary consumers usually eat plant material and are herbivores, examples include rabbits, caterpillars, cows and sheep.
• An herbivore or omnivore is an animal that eats both plants and meat, also known as a primary consumer.
• Mosquito larvae are the primary consumers in the food chain above.
• A carnivore or omnivore which eats the primary consumer is called the secondary consumer.
• Dragonfly larvae are the secondary consumers in the food chain above.
• Trophic levels in an ecosystem are represented as a pyramid of biomass, which shows the total biomass of each trophic level.
• Biomass is the measure of the total mass of living material in each trophic level.
• Wood is considered biomass because it was recently a plant.
• Fossil fuels are not considered biomass because they are the remains of organisms that died millions of years ago and have been chemically changed from the original living tissue.
• A food chain is a sequence of feeding relationships between organisms, showing which organisms eat what and the movement of energy through trophic levels.
• In a food chain, the clover has more biomass than all the snails, which have more biomass than all the thrushes and so on.
• Pyramids of biomass are always perfectly shaped, indicating a healthy ecosystem.
• If the pyramids of biomass are not perfectly shaped, then the ecosystem is likely to be unhealthy and in danger.
• The biomass at each trophic level must reduce in an ecosystem.
• An example of a food chain is: clover → snail → thrush → sparrowhawks.