Basic research develops the fundamental science that underpins all applied research. It uses every experimental approach possible, every kind of instrumental observation, every epidemiological and other analytic technique. It uses social-scientific methods where these can illuminate basics. It studies simplified "model" systems, in search of insights and techniques that will help study (messier) natural systems. It develops methods.
Much of the task of basic research is to study baseline functioning and health: metabolic mechanisms, hormonal controls, immune responses, and the phenomena of conception, inheritance, development, cognition, memory, and aging. It studies the materials of the body, flows of energy, and how the body interacts with various environments.
Basic research also studies abnormal functioning, and disease states and processes. And it studies bacteria, viruses, fungi, worms, mites, radiation, noise, toxins, dietary factors, stress factors, dusts, allergens—all the agents and risk factors that can affect health.
Much basic biomedical research does not need to use personally identifiable data, but some of course does.