Substances react chemically in characteristic ways with other substances. Many different people in different cultures have made and continue to make contributions to science and technology. Science and technology are reciprocal. Science helps drive technology, as it addresses questions that demand more sophisticated instruments and provides principles for better instrumentation and technique. Technology is essential to science, because it provides instruments and techniques that enable observations of objects and phenomena that are otherwise unobservable due to factors such as quantity.
Technology also provides tools for investigations, inquiry, and analysis.
Regular exercise is important to the maintenance and improvement of health. Food provides energy and nutrients for growth and development. Nutrition requirements vary with body weight, age, sex, activity, and body functioning. Risks and benefits Risk analysis considers the type of hazard and estimates the number of people that might be exposed and the number likely to suffer consequences. The results are used to determine the options for reducing or eliminating risks.