Which of the following is not a part modern cell theory

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

What molecules will be best used to compare different species with the exact same sequence of amino acids? why would two species have the same protein even if the molecules in question is different? (hint: transcription to translation to protein).

Resperation is a way to release carbon back into the atmosphere