For many centuries, scientists believed there were only two kingdoms, or groups of living things: plants and animals. But Anton van Leeuwenhoek made microscopes in the 17th century that also proved there are microorganisms, or microbes. Microbes can help keep people stay healthy, but some also can make people sick.

Скачать книгу бесплатно (pdf, 5.81 Mb)

---

Читать «Investigating Simple Organisms: Life Science »