More exposure to the antibiotic by non-resistant bacteria causes change in its structure against the environment and as a result of that change the bacteria get resistance against that antibiotic. No, farmers should not be allowed to put low doses of antibiotics in animal feed because it has no effect on the antibiotic-resistant bacteria. The farmer should use another antibiotic on the antibiotic-resistant bacteria which they have no resistance.
The only way for a cell to use energy stored within a molecule is in this example would be to break the bond between 1 and two because it would be impossible for energy to get to 3, 4, 5.
