Which trophic level contains the organisms that are the source of chemical energy used in an ecosystem?

Food contains a sugar called ( ), which is broken down in a process called cellular ( ). this process uses ( ) to break down food molecules and provide energy for cells. fill in the parentheses

Ialready know the answers to these questions and they are on the attachment. but i just need to know why that answer is the correct one. plz asap! this is for a report that i need to email by 10!

Drag each label to the correct location on the chart. match the function to the type of tissue