Antibiotics are medicines that help in the treatment of bacterial infections. They work by either killing the bacteria or preventing them from reproducing and spreading.

Antibiotics are ineffective against viral infections. This is because viruses do not have cellular structures such as cell walls which antibiotics typically target.

Over-prescription and misuse of antibiotics can lead to antibiotic resistance. This is a major concern, as bacteria can evolve, due to natural selection, to become resistant to these drugs.

Antibiotic resistance can spread between different strains of bacteria. This can make previously treatable bacterial infections more dangerous and difficult to control.

Penicillin, discovered by Alexander Fleming, was the first widely used antibiotic. It was discovered accidentally when Fleming noticed a mould (Penicillium notatum) was effective in killing bacteria.

There are different types of medicines aside from antibiotics. Painkillers, for example, do not tackle the cause of disease but help reduce symptoms such as pain and fever. This can make individuals feel better and possibly help the immune system fight off the infection.

Other medicines, like antivirals and antifungals, are used to combat viral and fungal infections respectively.

Miller and Urey's experiment showed how simple organic molecules, like amino acids, could have first been made on the early Earth. While the exact conditions of early Earth may have been different than the conditions in the Miller-Urey experiment, it highlighted the possibility of life originating from simple chemical processes.

The development, testing, and regulations around new medicines are strict to ensure safety. Stages include preclinical testing on cells and animals, followed by clinical trials on human volunteers. These stages assess the effectiveness and examine side effects. It can take many years for a new drug to pass through these checks and safety measures.

Vaccinations are an important way of controlling infectious diseases within a population. They train the immune system to attack certain diseases by injecting a harmless version of the pathogen. This leads to immunity without suffering the symptoms of the disease.

Herd immunity occurs when a large percentage of the population is vaccinated, reducing the probability of a pathogen infecting and spreading through the population. This can protect individuals who can't receive vaccinations due to health reasons.

Hygiene practises such as washing hands regularly and sterilising medical equipment also play a significant role in preventing the spread of infections.

Lifestyle factors can also contribute to disease. Poor diet, lack of exercise, alcohol misuse, and smoking can lead to health conditions such as heart disease, stroke, type II diabetes and lung cancer.