Life can be defined using a hierarchy of complex biological structures and systems. This hierarchy is arranged in levels which traditionally extend from atoms (lowest level) to biospheres (highest level) with each level representing an increase in organizational complexity. Each component in the hierarchy is primarily composed of a basic unit in the previous level (Buehler).
According to Buehler the hierarchy of life is the biological organization of organisms. The higher degree of order of an organism is termed as organization-the main principle by which individual organisms of same species share similar structural arrangements.
The atom is the lowest level of the hierarchy of life. It consists of electrons surrounding a centrally placed nucleus. Second to the atom is the molecule made up of at least two atoms held together by strong chemical bond in a specific organization. Examples of molecules include proteins, sugars and fatty acids. A group of functional molecules form an organelle.
The cell which represents the fourth level is the basic unit of life. It is formed through grouping of organelles. Several cells form a tissue and several tissues form an organ. A group of organs performing same functions form an organ system such as the digestive and circulatory systems.
Animals, plants or Fungi can be described as the basic living systems which are organisms while several organisms that belong to the same species together form a population. Groupings of more than one populations form a community. These populations and communities in turn create of an ecosystem-representation of the total numbers of organisms that habitat a given place. These organisms interact with all the components within the physical environment. Different ecosystems form the biosphere-highest level of hierarchy of life.
One major debate that has emerged as a result of scientific studies on the hierarchy of life is the controversial debate on cloning (Vaknin). Scientists have come up with two type of cloning. One is the therapeutic cloning which involves the harvesting of stem cells from embryos and developing them into any type of mature functional cell. The second kind of cloning is called nuclear transfer which involves embedding a nucleus from a donor to a cell whose nucleus has been detached. Afterwards, the egg is coaxed into developing specific tissues (Sherwood, 9).
Scientists argue that they could make major medical breakthroughs through cloning while most of the society rejects cloning. This subject evokes moral and ethical dilemmas. Cloning of babies in particular is seen as a process that will lead to an imbalance in nature and religious groups which look at life as divine want it to occur naturally. Cloning of humans is argued to be against the universal right to life.