sentences: producers are a source of food energy in an ecosystem & living things are a part of an ecosystem ->  producers are a source of food energy for living things  living things all require energy for survival & if something requires something else then that something requires a source of that something else ->  living things all require a source of energy for survival  producers are a source of food energy for living things & living things all require a source of energy for survival ->  living things all require a producers for survival  living things all require a producers for survival & if a living thing requires something for survival then that living thing is dependent on that something ->  all living things are dependent on producers  green plants provide food for themselves / animals / consumers by performing photosynthesis & to provide something can mean to produce something ->  green plants produce food for themselves / animals / consumers  green plants produce food for themselves / animals / consumers & a producer produces its own food ->  green plants are a kind of producer  all living things are dependent on producers & green plants are a kind of producer -> all living things are dependent on plants because plants are a kind of producer