Final answer:
Viruses are not considered living because they cannot reproduce or carry out metabolic processes without a host, do not maintain homeostasis, and are not made of cells. Despite having genetic material and the ability to evolve, these characteristics are not sufficient for viruses to be classified as living organisms. (Option b)
Step-by-step explanation:
Scientists debate whether viruses are alive because they exhibit some but not all characteristics of living organisms. Viruses contain genetic material, like DNA and RNA, and exhibit the capacity to evolve. However, they do not qualify as living because they are not made of cells, cannot maintain homeostasis, lack a metabolism, and cannot initiate replication without a host. Essentially, viruses are acellular entities that require a host cell's machinery to reproduce, making them distinct from living organisms that can grow, metabolize, and reproduce independently.
A virus is basically genetic material encased in a protein coat, and is far simpler than even the simplest prokaryotic cell. Although viruses can evolve, demonstrating a key hallmark of living organisms, their inability to carry out necessary life functions on their own puts them in a grey area, challenging the traditional definition of life. As a result, many scientists do not classify viruses as living entities.