False there may be two or more dependent variables in a well designed experiment
Equation: sunlight + Carbon Dioxide (6CO2) + Water (6H2O) = Glucose + Oxygen
Reactants: Sunlight + Carbon Dioxide + Water
Products: Glucose and Oxygen
The air outside your body because when you tried to hold your breath the pressure builds and forces your body to breath by letting out the air but depending the altitude you are the pressure can change hope this helps
If an animal became extinct such as a rabbit (even tho they abut extinct) then any animal who only ate rabbits would probably become extinct too an that would keep on happening until no more animals in the world unless they adapted to eating other animals
Lungs,heart,stomach,intestines