Zoology is the study of animals and their behavior. Zoologists may study a particular species or group of species, either in the wild or in captivity. Zoologists study animals and their interactions with ecosystems. They study their physical characteristics, diets, behaviors, and the impacts humans have on them. read more
Since environmental science is an interdisciplinary field involving physics, chemistry, geology, biology, climatology, etc., I would say biology and environmental science intersect each other. Theory of evolution states that all lives are evolved due to natural selection, which can be interpreted as lives are defined by its environment. read more