Most ninth grade biology course curriculum's cover evolution, cells and cell division, heredity and genetics, cellular respiration, ecology, photosynthesis, and human biology, but every high school curriculum is different. Most courses also allow students to dissect an animal such as a pig or frog during lessons about human anatomy.
Most high school courses cover the basics of each of these topics. However, certain schools offer advanced programs that delve deeper into certain subjects. For example, certain curriculum's may not focus as much on photosynthesis and instead go into great detail about human anatomy and offer more dissections. If a school wants students to take an advanced placement exam, they may teach students only material that appears on the exam.
Most of the topics in a biology course are related to one another. For example, students may learn about evolution and how it works at the beginning of the year. Later, they may learn about how cells have evolved, and then they learn how that evolution took place thanks to the earlier lesson about evolution.
Biology is defined as the study of life, which makes it a very broad subject. The anatomy of the body and the way ecosystems evolve are both within the field of biology.