Virus Definition Biology Gcse

Viruses infect all types of life forms from animals and plants to microorganisms including bacteria and archaea. Virus infectious agent of small size and simple composition that can multiply only in living cells of animals plants or bacteria.

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They can often survive outside a host for long periods of time.

Virus definition biology gcse. We say strains of virus and. A pathogen is a microorganism that causes a disease. Learn about the history types and features of viruses.

A virus is often housed in a protein coat or protein envelope a protective covering which allows the virus to survive between hosts. All types of pathogen have a simple life cycle. The life cycle of a virus is the same as other pathogens.

There are four main types of pathogen. Movement respiration sensitivity nutrition excretion reproduction and growth. Viruses are very small particles capable of infecting every type of living organism.

Viruses are written by malicious programmers who wish to cause problems for other computer users. Free biology revision notes on viruses. When they do infect a suitable host cell or cells they replicate.

Designed by the teachers at save my exams for the cie igcse biology 0610 0970 syllabus. A virus is a chain of nucleic acids dna or rna which lives in a host cell uses parts of the cellular machinery to reproduce and releases the replicated nucleic acid chains to infect more cells. Viruses are not alive because they do not complete all of the seven life processes.

Since dmitri ivanovsky s 1892 article describing a non bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by martinus beijerinck in 1898. The primary source of infection these days are email attachments followed by illegal software and. They infect a host reproduce themselves or replicate if.

They are parasitic and can only reproduce inside living cells. Viruses possess unique infective properties and thus often cause disease in host organisms. A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism.

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Gcse Biology Revision Communicable Diseases Teaching Resources

Structure Plant Cell Animal Bacteria Cells Prokaryotes Eukaryotes Similarities Differences Function Of Nucleus Cytoplasm Cell Membrane Mitochondria Ribosomes Cell Wall Vacuole Chloroplasts Subcellular Structures Igcse O Level Gcse Biology Revision