Final answer:
Bioethics, which examines ethical dilemmas in medicine and biology, includes three main sub-disciplines, but environmental ethics is not one of them. Bioethics encompasses issues such as patient autonomy and the use of human subjects in research. It falls under applied ethics, distinct from metaethics and normative ethics.
Step-by-step explanation:
Bioethics is commonly understood to include three main sub-disciplines, except for environmental ethics.
Bioethics is a branch of applied ethics that deals with the ethical issues that arise from advances in biology, technology, and medicine. This field grapples with debates about patient autonomy, medical resources distribution, human experimentation, and life-and-death medical decisions.
The three main areas of ethics are metaethics, which explores the nature of moral values and ethical statements; normative ethics, which analyzes the criteria for what makes an action right or wrong; and applied ethics, which deals with the practical application of ethical principles to specific controversial issues, including topics within bioethics.