Question

Which one of the following are intracellular obligate parasites?
A. Bacteria
B. Viruses
C. Slime moulds
D. Blue- green algae

Answer 1

Hint: An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce.

Complete step by step answer:
1.Bacteria
-Bacteria are microscopic, single-celled organisms, in every environment, both inside and outside other organisms.
- Some bacteria are harmful, but most serve a useful purpose. They support many forms of life, both plant and animal, and they are used in industrial and medicinal processes.
2.Virus:
-A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism.
-Viruses infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.
-Viral populations do not grow through cell division, because they are acellular. It is an obligate parasite.
-They use the machinery and metabolism of a host cell to produce multiple copies of themselves, and they assemble in the cell.
- When infected, the host cell is forced to rapidly produce thousands of identical copies of the original virus.
3.Slime moulds:
-Slime moulds is an informal name given to several kinds of unrelated eukaryotic organisms that can live freely as single cells, but can aggregate together to form multicellular reproductive structures.
4.Blue green algae:
-Blue-green algae, or cyanobacteria occur commonly in natural waters, where they play an important role in the natural cycling of nutrients in the environment and the food chain.
Cyanobacteria appear to have originated in freshwater or a terrestrial environment.

So, the answer is B. Viruses

Note:
Some of the Diseases caused by virus-
-Common human diseases caused by viruses include the common cold, influenza, chickenpox, and cold sores.
- Many serious diseases such as rabies, Ebola virus disease, AIDS (HIV), avian influenza, and SARS are caused by viruses.