Final answer:
A submicroscopic structure capable of infesting plants and animals, including bacteria, is 1) Virus.
Step-by-step explanation:
1)Viruses are unique entities that fall between living and non-living classifications. They consist of genetic material (either DNA or RNA) enclosed in a protein coat called a capsid. Viruses lack the cellular machinery for metabolism and reproduction, relying on host cells to replicate. This adaptability allows viruses to infect a wide range of hosts, including plants, animals, and even bacteria.
Unlike bacteria (2), fungi (3), and protozoa (4), viruses do not possess the cellular structure or independent metabolic processes required for life. Instead, they rely on host cells to carry out these functions, making them obligate intracellular parasites.
Viruses are known for their ability to cause a variety of diseases in different organisms. The specificity of viral infections is often dictated by the interactions between viral surface proteins and host cell receptors. Once inside the host cell, the virus utilizes the cellular machinery to replicate and produce more viral particles.
This process can lead to the disruption of normal cellular functions and the manifestation of symptoms associated with the viral infection. The study of viruses is essential in understanding the dynamics of infectious diseases and developing strategies for prevention and treatment.
In summary, viruses are submicroscopic entities that lack the cellular structure of living organisms but are capable of infesting and causing diseases in a diverse range of hosts, including plants, animals, and bacteria. Their unique mode of replication and dependence on host cells distinguish them from other microorganisms like bacteria, fungi, and protozoa.