Why didn't people know about germs or microbes before the mid-1800s?

Jason adds the antibiotic penicillin to a bacterial culture. the bacteria develop genetic modifications in their genome, which gives them resistance to the antibiotic penicillin. what caused this genetic modification?

If a strand of dna has 35% thymine. what is the percentage of cytosine, adenine, guanine?

Acell goes through cellular respiration and produces atp which it then uses to move a molecule across the cell membrane. how does the energy in the original glucose molecule change during this process? (2 points)