Biology, science of living things. The most important subdivisions of biology are zoology, the study of animals, and botany, the study of plants. Advances in scientific knowledge have led to an increase in the number of fields of biological study. Some biologists study subdivisions of the animal and plant kingdoms: entomology (the study of insects), mycology (fungi), paleontology (fossils), and microbiology (microorganisms). The they were mainly interested in anatomy, still an important field of study. As early biologists accumulated information about plants and animals, they noticed that some closely resembled others. Such observations were the basis for a system of classification. The Swedish naturalist Carolus Linnaeus devised a method of classifying living things, called taxonomy, in which each plant and animal is assigned a unique name. Physiology is the study of the workings of organs and how they are affected by disease. The study of diseases themselves is called pathology. Biology is also connected with other scientific disciplines. Biochemistry is the application of chemistry to biology, and biophysics is the application of physics to biology. The study of animal behavior often employs the techniques of psychology. Molecular biology studies biological processes at the level of the molecule. The study of genetics, dealing with heredity, has become increasingly important. Genetic engineering is now making possible the production of substances by means of intervention in genetic processes.