Methods of studying biology
There are four main methods of studying living organisms. Observation is the oldest: the researcher collects information with the senses, such as sight and hearing, without disturbing nature; today a video camera can help. In comparison, two organisms are set side by side and their similarities and differences are found. In the historical method, organisms that lived long ago are compared with living ones; for example, palaeontologists (scientists who study ancient organisms) found that the ancestors of horses were smaller and, over time, their legs lengthened and they became hoofed, fast-running animals. In an experiment the researcher creates the conditions and watches what changes. Usually only one factor is changed, the others are kept the same, and the result is recorded. In the 17th century the Italian doctor Francesco Redi showed by experiment that fly maggots do not appear in meat by themselves; they come from eggs laid by flies. Scientists usually use these methods together.
Mini-experiment (at home with a parent): put damp cotton wool in two cups and place 5 bean seeds on each. Leave one at room temperature and put the other on the bottom shelf of the refrigerator (cool); give both the same amount of water. For 4–5 days record in a table how many seeds have sprouted, and say which factor was changed. Safety: do not eat the seeds, open the refrigerator only with an adult’s permission, and wash your hands with soap afterwards.