NEET BIOLOGY

Detailed explanation-1: -Virus and cell size comparison. Human viruses can vary in size but are generally in the range of 20–200 nm in diameter. In comparison, bacteria are generally 2–3 M in length, and an average human cell is 10–30 M.

Detailed explanation-2: -Viruses are microscopic infectious agents that contain genetic material, either DNA or RNA, and must invade a host in order to multiply. Predominantly, viruses are known for causing disease, as they’ve triggered widespread outbreaks of illness and death throughout human history.

Detailed explanation-3: -A virus is a submicroscopic infection agent, so that means it’s really, really small, so it’s submicroscopic. We can’t see them with a normal light microscope – you have to use very high resolution microscopy, which is electron microscopy, to see them. They are infectious, they will make people sick.

Detailed explanation-4: -Hence, virus particle is smaller than bacteria.

Detailed explanation-5: -The criteria used for classifying viruses into families and genera are primarily based on three structural considerations: (1) the type and size of their nucleic acid, (2) the shape and size of the capsids, and (3) the presence of a lipid envelope, derived from the host cell, surrounding the viral nucleocapsid.