How can we use rocks to determine how an area used to look in the past?

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).

In the sentence "a mining company will consider the distribution of coal when deciding how to mine the coal," what does the word distribution mean?

How do specific cell structures and organelles contribute to maintaining homeostasis in the cell?