Get Viruses Reinforcement Worksheet Answers

Viruses are tiny particles that cause disease in people, other animals, and plants. Different viruses cause the common cold, influenza (flu), chicken pox, measles, AIDS, and many other diseases. Viruses are so tiny that people can see them only with powerful microscopes. Some viruses have a spherical, or round, shape.

virus, infectious agent of small size and simple composition that can multiply only in living cells of animals, plants, or bacteria. The name is from a Latin word meaning “slimy liquid” or “poison.”

They cannot produce energy or control internal environments. They also lack ribosomes and cannot independently form proteins from molecules of messenger RNA. So, by these definitions of life, viruses are not alive. They are often called “obligate intracellular parasites.”

Nonliving characteristics include the fact that they are not cells, have no cytoplasm or cellular organelles, and carry out no metabolism on their own and therefore must replicate using the host cell's metabolic machinery. Viruses can infect animals, plants, and even other microorganisms.

The information stored in the virus — its genetic material — is either DNA or RNA. DNA is like the instruction manual for how to build the virus. RNA is like the translation of the instructions in a language that the cell machinery can read and make into proteins.

A virus is a lifeless particle with no control over its movements when it is outside the host cell.

Living things use energy. Outside of a host cell, viruses do not use any energy. They only become active when they come into contact with a host cell. Once activated, they use the host cell's energy and tools to make more viruses. Because they do not use their own energy, some scientists do not consider them alive.

Viruses are not made out of cells, they can't keep themselves in a stable state, they don't grow, and they can't make their own energy.

Viruses are non-cellular, microscopic, parasitic organisms with a size of a mere 20-300 mm. Although they do not have cellular material such as cytoplasms, ribosomes, etc to sustain by themselves, they have the genetic material to evolve and replicate which they do by attaching themselves to a host body.