Biology is the study of life, and the principles and compounds in chemistry form the foundation for it. Biology spans from studying the most minuscule structures inside cells, called organelles, to giant masses of land with specific climates, called biomes. Biologists study cells, genetics, anatomy and physiology of the body, evolution, and ecology. Biology is perhaps the most relevant to human life, as many biologists focus on studying our bodies and the components inside them, like cells and DNA.