Which never changes during physical change

Wht happens as electrons in the electron transport chain release their energy

Legumes, a type of plant, require rhizobia, a type of soil bacteria, to survive since these organisms fix nitrogen during photosynthesis. rhizobia use the legumes for food. what would most likely happen to the legume population if rhizobia suddenly became extinct?

What element does susan b. anthony include in this passage to strengthen her argument?