Why humans need organs, like the liver and pancreas, but amoebas do not.

They have no use for it, just like they dont have any type of respiratory organs like lungs.

Explanation:

In the case of nutrition and digestion they obtain food by capturing their prey with their pseudopodia. The food is internalized through a type of endocytosis known as phagocytosis. Nutrients are obtained as the enzymes digest the food inside the vacuole and when they are finished the food vacuole dissolves.

the way that the mass of carbon can be conserved through cellular respiration is through a process/law called the law of conservation of mass which even tho it undergoes a process, mass is not be destroyed or changed

for the points