All of the energy that flows through food chains comes originally from the sun
Arrows in food chains show what eats what
The arrows show the flow of energy through the system
What the arrows represent in a food chain
The flow of energy from one organism to another
Trophic level
Each feeding level in a food chain
Trophic levels
Producer
Primary consumer
Secondary consumer
Tertiary consumer
Keywords
Plants
Animals
Fungi/Bacteria
Decomposers
Producers
They produce their own food using carbon dioxide and water
Consumers
Things that eat other living things (can be herbivores, omnivores or carnivores)
Herbivore
An animal that feeds on plants
Carnivore
An animal that feeds on other animals
Omnivore
An animal that eats both plants and animals
Ecologists have calculated only 10% of energy available in a trophic level is taken up by the level after
Energy flow in a food chain
1. Sun
2. Producer
3. Primary consumer
4. Secondary consumer
5. Tertiary consumer
98% energy lost from sun to producer
90% energy lost from producer to primary consumer
90% energy lost from primary consumer to secondary consumer
90% energy lost from secondary consumer to tertiary consumer
Why only THREE consumers in the chain?
Biomass
The total mass of an organism
How is the energy from food used by organisms?
Movement
Nutrition
Excretion
Reproduction
Growth
Sensitivity
Respiration
Maintenance of body temperature
Energy from cellular respiration is transferred by heating the surroundings
Food pyramid
Each trophic level is represented by a horizontal bar, with the base representing the producer
Pyramid of energy
The width of the bar represents the amount of energy available at each level in the food chain, measured over a period of time
Most food chains only have a few links because energy is lost at each level, for example as heat, for movement, and in urine and faeces
Energy flow through producers
1. Most of the sunlight that falls on leaves is not absorbed and used
2. The overall efficiency of energy transfer during photosynthesis is less than 10%
3. Only about 1 - 5% of sunlight energy reaching the plant is transferred into useful chemical energy in the carbohydrates
Only about 10% of energy is transferred to the next trophic level
How energy is lost along the food chain
Escapes as heat in respiration to the surroundings
Some parts of the plant is not eaten e.g. roots
Some parts of the organism is not eaten/digested e.g. fur, teeth, bone, claws
Some materials are not absorbed and are egested e.g. urine, faeces
Organism uses the energy to stay alive
When organism die- energy is 'locked up' which transfers to decomposers
Eating meat is wasteful in terms of food energy
Food web
A series of food chains all connected to each other
Food webs are easily unbalanced if one population of organisms in the web disappears due to over-predation or hunting, disease, pollution, use of pesticides, lack of food, or emigration
Terrestrial, marine, and freshwater food webs are examples of ecosystems
Quadrats
Tools biologists use to estimate the number of plants in an area
Sampling
Taking small samples to investigate distribution of organisms in a large area
Distribution
The way living things are spread out in their habitat