Model systems refer to simplified and controlled experimental systems that are used to study a specific biological process or phenomenon. These systems are often chosen because they are easier to manipulate and study compared to more complex organisms or environments. Model systems can include everything from cell cultures and tissue cultures to genetically modified organisms such as fruit flies, mice, or bacteria. These systems allow researchers to investigate fundamental biological processes, test hypotheses, and gain insights into more complex biological systems. By studying model systems, scientists can make discoveries that have implications for understanding human health, disease, and evolution. Overall, model systems are valuable tools in biological research for unraveling the mysteries of life.