food chains

• food chains always start with a producer . producers produce their own food using energy from the sun
• producers are usually green plants or algae- they make glucose by photosynthesis
• when a green plant produces glucose, some of it is used to make other biological molecules in the plant- these are the plants biomass (mass of living material)
• biomass can be thought of as energy stored in a plant
• energy is transferred through living organisms in an ecosystem where organisms eat other organisms
• producers are eaten by primary consumers, these are then eaten by secondary consumers. secondary consumers are eaten by tertiary consumers
• consumers that hunt and kill other animals are called predators, they eat prey.
• in a stable community containing prey and predators, the population of any species is limited by the amount of food available.
• if population of prey increases, then so will population of predators. If number of predators increase, population of prey decrease
• predator-prey cycles are always out of phase with each other because it takes a while for one population to respond to changes of the other population