Biological Classification and Microorganisms

Polio virus is a well-studied example of a polyhedral virus with icosahedral symmetry (approximately 30nm diameter, 60 structural subunits). TMV (Tobacco Mosaic Virus) is rod-shaped (helical). Vaccinia is a complex brick-shaped virus. Bacteriophages have complex geometric shapes but are typically described as having a head-tail structure.

Wendell Meredith Stanley was the first to crystallize the tobacco mosaic virus (TMV) in 1935, demonstrating that viruses could be isolated in crystalline form, which was crucial in understanding their nature. Von Manuel, Jack Karl, and Ronald Ross (who worked on malaria) are not associated with this discovery.

Tobacco Mosaic Virus (TMV) is the classic example of a helical virus. Its RNA genome is surrounded by protein subunits arranged in a helical spiral around the nucleic acid, giving it a rod-like appearance.

Viruses are obligate intracellular parasites (true), have an outer shell called capsid (true), and replicate but don't grow/metabolize independently (true). However, capsids are made of protein subunits (capsomeres), NOT polysaccharides, making option D the correct 'not a characteristic' answer.

Ernst Haeckel proposed the three-kingdom system in 1866, adding Protista to the existing Animalia and Plantae kingdoms to include unicellular organisms.

Cyanobacteria are prokaryotic organisms, meaning they lack a membrane-bound nucleus and organelles. Fungi are eukaryotes, and the other options are not biological classifications in this context.

Robert Whittaker proposed the five-kingdom classification system in 1969, which categorized organisms into Monera, Protista, Fungi, Plantae, and Animalia.

Under Whittaker's five-kingdom classification system, the kingdom Protista specifically comprises all unicellular eukaryotic organisms. Fungi, Plantae, and Animalia primarily consist of multicellular eukaryotes, though some simple fungi like yeasts are unicellular.

Bacteria and Cyanobacteria are prokaryotic organisms. In Whittaker's five-kingdom system, all prokaryotes are placed in the kingdom Monera.

Fungi are heterotrophic organisms that lack chlorophyll and are often referred to as non-green thallophytes. They were separated from the plant kingdom in Whittaker's classification.

Robert Whittaker proposed his five-kingdom classification system in 1969.

Eukaryotic cells contain 80S ribosomes, which are composed of 60S and 40S subunits. Prokaryotes typically contain 70S ribosomes.

Schlessinger is credited with the purification of viruses using differential centrifugation in the early 1930s.

Bawden and Pirie were the scientists who purified the Tobacco Mosaic Virus (TMV) and demonstrated that it consisted of ribonucleoprotein.

Euglena is a protist that contains chloroplasts (allowing photosynthesis like plants) but can also ingest food (like animals), making it a classic example of an organism with dual characteristics.

Viruses are classified based on various criteria, including the type of nucleic acid (DNA or RNA), the strandedness of the genome, and the presence or absence of a lipid envelope.

Prokaryotes are defined by the lack of a membrane-bound nucleus and membrane-bound organelles.

Eukaryotes are defined by the presence of a true membrane-bound nucleus and various membrane-bound organelles.

Most viruses are very small, typically ranging from 10 to 200-300 nanometers in size.

Prokaryotic cells contain 70S ribosomes, which are composed of 50S and 30S subunits.