Final answer:
The bacteria in the scientist's observation showing growth at 1,000 times the antibiotic concentration are likely resistant, meaning the antibiotic cannot effectively kill them due to natural selection and resistance mechanisms.
Step-by-step explanation:
A scientist observed a certain type of a particular bacteria growing in a substance that had a 1,000 times higher amount of the antibiotic that targets this bacteria. This observation indicates that the bacteria are likely resistant to the antibiotic. Bacterial antibiotic resistance occurs through natural selection when bacteria with mutations that confer survival advantages in the presence of antibiotics reproduce more successfully than those without such mutations. Moreover, resistance can be spread through horizontal gene transfer, where resistant genes are shared between bacteria. In this case, the antibiotic can no longer effectively target and kill the bacteria which allows the resistant bacteria to propagate and become more prevalent.
The antibiotic resistance mechanisms include degradation or modification of the antibiotic, change of the antibiotic target, prevention of antibiotic entry, or removal of the antibiotic from the bacteria through efflux pumps.