Trophic levels, food chains and webs Flashcards
How do pyramid diagrams represent energy transfers within an ecosystem?
Four main trophic levels.
At each level, some energy contained is available for food for the next level in the hierarchy.
Each level decreases in size - 90% energy is lost through life processes e.g. respiration, movement and excretion.
Only 10% is available for the next level - the number of living organisms decreases.
What is the first (bottom) pyramid trophic level?
Producers/autotrophs.
Green plants - produce their own food through photosynthesis by using energy from sunlight.
What is the second (from bottom) pyramid trophic level?
Primary consumers/herbivores.
Insects, fish, birds and mammals that eat producers.
What is the third (from bottom) pyramid trophic level?
Secondary consumers/carnivores.
Meat-eaters.
Primarily survive on consuming herbivores.
What is the fourth (top) pyramid trophic level?
Tertiary consumers/omnivores.
Top predators.
Eat the secondary consumers.
What operates at each trophic level of the pyramid?
Detritivores/decomposers.
Detritivore - an animal that feeds on dead material/waste products e.g. slugs.
Decomposer - an organism that breaks down dead plants, animals and waste matter e.g. fungi/bacteria.
What does a food chain show?
The flow of energy within an ecosystem.
Usually has four links as there are four levels in a trophic pyramid.
Each link in the chain feeds on/obtains its energy from the previous link, and is in turn, consumed by and provides energy for the following link.
3 examples of a food chain.
Rose leaf/aphid/blue tit/sparrowhawk.
Phytoplankton/zooplankton/cod/human.
Corn/field mouse/weasel/fox.
What does a food web show?
A large number of food chains which operate within a single ecosystem.
Many animals have a varied diet.
Plant/animals are likely to be food for a number of different consumers - resulted in complex feeding interactions within an ecosystem.
Humans (omnivores) operate at several trophic levels.
