What biology covers
Biology is the study of living things — how they are built, how they work, how they inherit traits, and how they change over time. It is usually the first high-school science, and for many students the most relatable, because it is the science of themselves.
The core themes
A full-year biology course is organized around a few big ideas that connect everything:
- Cells — the basic unit of life; structure, function, energy (photosynthesis and respiration)
- Genetics & heredity — DNA, genes, inheritance, and modern biotechnology
- Evolution — the unifying theory that explains life's diversity and relatedness
- Ecology — how organisms interact with each other and their environment
- Human biology — body systems and health
As the geneticist Dobzhansky famously put it, nothing in biology makes sense except in the light of evolution — the thread that ties the whole subject together.
In the K-12 arc
Living things appear from the earliest grades (habitats, life cycles, the human body), deepen in middle school (cells, body systems, ecosystems), and become a formal course in 9th or 10th grade. Motivated students take AP Biology or IB Biology, both known for heavy content and lab work.
NGSS in biology
Under the NGSS, biology is taught through investigation and explanation, not memorization of terms. Students model cellular processes, analyze real ecological and genetic data, and build evidence-based arguments — the same practices working biologists use.
How biology is measured
Biology is often the science chosen for a state's required high-school science exam. AP Biology and IB Biology exams grant college credit and are respected by admissions. Lab practicals and data analysis are increasingly part of assessment, reflecting the hands-on nature of the field.
Common challenges
Biology's reputation as “just memorization” is its biggest trap — the vocabulary load is real, but understanding the processes and connections matters far more than memorizing terms. Two topics deserve care: genetics (which leans on probability and abstract reasoning) and evolution (well-established science that is sometimes a sensitive topic; it is taught as the foundational theory of biology).
Careers biology opens
Biology is the gateway to medicine, nursing and allied health, plus biotechnology, environmental science, agriculture, research, veterinary medicine and more — many among the largest and fastest-growing career areas. See the BLS Occupational Outlook Handbook and the Careers section for current fields and pay.
How families can help
- Explore nature, gardens, zoos and aquariums together
- Connect biology to health, food and current science news
- Watch quality nature and science documentaries
- Focus on understanding processes, not memorizing lists
Lessons and related resources
See the Science lesson library, the parent subject Science, and siblings Chemistry and Earth & Environmental Science.
Frequently asked questions
- What grade is biology taught? Usually 9th or 10th grade, often as the first high-school science course.
- Is AP Biology hard? It's content-heavy with significant lab work, but widely respected and often accepted for college credit. Strong reading and study habits help.
- Why is evolution central to biology? Evolution explains the diversity and relatedness of all life, so it ties every other topic together. It's the foundational theory of the field.
- Is biology just memorization? No, though the vocabulary can feel that way. Understanding how processes work and connect matters far more than memorizing terms.
- What careers come from biology? Medicine, nursing and allied health, biotechnology, environmental science, veterinary medicine, agriculture and research, among many others.