The human body has systems that interact with one another and perform specific functions. A diet of appropriate food provides energy for a healthy human body. Vitamins and minerals help keep the body healthy. Humans must care for their bodies to stay healthy. People of different races, cultures and genders have developed technologies that improve human health and quality of life.
Animals can survive only in environments in which their needs can be met.
Living things that can better adapt to changes in their environment have a greater chance of survival. Species of animals that are not able to adapt to changes in their environments can become endangered or extinct. Light travels through some materials better than others. Light travels through air in straight paths. Shadows are created when objects interrupt the path of light.