What kind of species can harm an ecosystem or human health when introduced into the new environment? A species whose introduction does or is likely to cause economic or environmental harm or harm to human health is a(n) species. These species are to the new environment.

This would be an invasive species which is not native to the environment. It can cause harm either because it over grows (if it's a plant.) Or if it's an animal, it will reproduce and most likely take over the environment. This is because it feels the need to compete for materials, but ends either taking most or all of it. Which then ruins the food chain depending on it's diet. If it's eating a plant, then other animals that eat that plant no longer have any food. And vice versa if it's feeding on animals. Other predators, no longer have their food.

the cell theory states that all living things including animals, as well as plants, are made of cells.