Host (biology)

In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna. Examples of such interactions include a cell being host to a virus, a bean plant hosting helpful nitrogen-fixing bacteria, and animals as hosts to parasitic worms, e.g. nematodes.

The word "guest" is also (more rarely) used in biology to refer to the organism that lives with the host.

Definitions

A host cell is a living cell in which a virus reproduces.

A primary host or definitive host is a host in which the parasite reaches maturity and, if possible, reproduces sexually.

A reservoir host can harbour a pathogen indefinitely with no ill effects. A single reservoir host may be reinfected several times.

A secondary host or intermediate host is a host that harbors the parasite only for a short transition period, during which (usually) some developmental stage is completed. For trypanosomes, the cause of sleeping sickness, strictly, humans are the secondary host, while the tsetse fly is the primary host, given that it has been shown that reproduction occurs in the insect.Cestodes (tapeworms) and other parasitic flatworms have complex life-cycles, in which specific developmental stages are completed in a sequence of several different hosts.

Host

Host (masculine) and hostess (feminine) most often refer to a person responsible for guests at an event or providing hospitality during it, or to an event's presenter or master or mistress of ceremonies. Host or hosts may also refer to:

Computing

Biology

Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, evolution, distribution, and taxonomy. Modern biology is a vast and eclectic field, composed of many branches and subdisciplines. However, despite the broad scope of biology, there are certain general and unifying concepts within it that govern all study and research, consolidating it into single, coherent fields. In general, biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the synthesis and creation of new species. It is also understood today that all organisms survive by consuming and transforming energy and by regulating their internal environment to maintain a stable and vital condition.

Subdisciplines of biology are defined by the scale at which organisms are studied, the kinds of organisms studied, and the methods used to study them: biochemistry examines the rudimentary chemistry of life; molecular biology studies the complex interactions among biological molecules; botany studies the biology of plants; cellular biology examines the basic building-block of all life, the cell; physiology examines the physical and chemical functions of tissues, organs, and organ systems of an organism; evolutionary biology examines the processes that produced the diversity of life; and ecology examines how organisms interact in their environment.