As the study of living things, biology may deal with units smaller than a single cell or as large as an ecosystem covering a continent. It is an immensely varied field and can open doors to specializations in medicine, agriculture, genetics, zoology, and more.
In other words, the comprehensive nature of a biology degree is one of its strengths. Between studying fundamental science, lab work, and learning to solve practical problems, a graduate will gain all the skills necessary to understand the natural world. They may, in fact, find that there is considerable overlap in the knowledge needed to care for animals in a zoo and to investigate new plant compounds for medicinal properties.