What organs make up the gastrointestinal tract? what are the accessory organs of digestion?

What volume of a 0.25 m solution can be made using 0.55 moles of ca(oh)2

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?

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?