Tag: biology

Viruses can be made into a crystalline form. TMV became the first virus to be crystallized in 1935. One crystal of viruses consists of thousands of viruses. The crystallization of viruses was first done by Stanley. Algae, Amoeba and Sperm cannot be crystallised.

The correct answer is C.

All viruses live inside host cell, they cannot function outside the cell. Unlike bacteria which rarely live in the host cell. Therefore, (c) is the correct answer.

Virus is the microorganisms which have properties of living and non-living both. They have a specific structure which consists of head and tail. Head is composed of several protein units known as capsomeres which enclose the genetic material made up of RNA or DNA. They have a lipid envelope derived from the host cell membrane which lies outside the capsomere. They occur in crystalline form outside the body of the host but as it enters the host cell it injects its genetic material which replicates vigorously. The replicated materials are further packed in the new protein coat formed using host protein and is thrown out by the lysis of cell membrane.

There are $5$ codes of nomenclatures:- 

A virus is a small infectious agent, that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. All viruses are obligate parasites; i.e., they lack metabolic machinery of their own to generate energy or to synthesize proteins, so they depend on host cells to carry out these vital functions. Thus, option C is correct.
Viruses do not possess their own metabolic system. So, depends on host machinery. Thus, option A is wrong.
All viruses contains either DNA or RNA as genetic material but, not both. Thus, option B is wrong.
The protein coat of virus is called as capsid. Thus, option D is wrong.

Viruses play an important role in horizontal gene transfer and genetic diversity. The evolution history showcases the origin of viruses as to have evolved from plasmids when pieces of DNA moved between cells. As
big bits of cellular DNA became independent and some DNA stuck with cell genomes. Thus, the correct answer is option D.

• A virus is an organism that can be considered both living and non-living. 
• It can be considered as living when it is inside any host (bacterium) as the virus infects the host cell and replicates inside it making several copies of it. 
• When it is outside the host cell, it is non- living as it can not carry out its life- processes of either reproducing or digestion etc.
• Thus, option A is correct here.

Viruses are non-cellular organisms and replicate only when they infect the host cell. 

Reproducing is one of the characteristics of the living organisms. Viruses definitely multiply. Viruses must use host cells to create more virions. Since viruses don’t have organelles, nuclei or even ribosomes, they don’t have the tools they need to copy their genes and create whole new virions. Instead, viruses enter living cells and then hijack the host’s cellular equipment to copy viral genetic information, build new capsids and assemble everything together. So, the correct answer is 'They can reproduce'.