Jacob is unsure about how to focus a slide under the microscope. What would be Jacob’s best course of action? Ask the teacher for instructions. Ask his lab partner for instructions. Watch another student, and copy what he or she does. Use the trial-and-error method until the slide focuses.

You should ask your partners or teacher

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.