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What Outside Agents Affect Organisms in Biology?

Most organisms interact constantly with the outside world. The human body, for example, is susceptible to a variety of outside agents. The skin helps to protect the human body from these outside agents, but points of entry like the mouth, nose or even an open cut allow outside agents to affect the inner workings of the human body.

  1. Viruses

    • One of the most common outside agents that affect the various inner workings of an organism are viruses. The common cold is an example of a virus that virtually everyone is exposed to at some point in his life. The common cold virus is fairly benign and causes a number of symptoms, but usually does little lasting damage. Many other viruses, though, can do a great deal of damage to complex organisms like the human body.

    Bacteria

    • Bacteria are another form of outside agent that can enter an organism and affect it in many different ways, some beneficial, others benign and many damaging to various degrees. Flesh-eating disease is one uncommon but very damaging bacterial infection that profoundly harms the human body. The bacteria usually enters the organism at the site of a wound or trauma and begins to replicate, destroying portions of the body in the process.

    Pollutants

    • Pollutants and chemicals are another category of often unnatural outside agents that can affect the inner workings of many different organisms. There are many man-made pollutants and chemicals in the environment, but one natural example might be the ash from a volcanic eruption. When inhaled, it bonds with the small amount of liquid present in the lungs and forms a cement-like substance, which can lead to death. This affects humans as well as many other kinds of organisms, particularly other mammals with respiratory systems similar to that of humans.

    The Sun

    • The radiation given off by the sun is one example of an outside agent that is accepted willingly into many organisms. Human skin, for example, converts sunlight into vitamin D, which is an important nutrient for many different internal bodily functions. The radiation from the sun is also a fundamental need of most plant life. Plants, through photosynthesis, convert the energy from sunlight, along with carbon dioxide and water, into simple sugars, which they then use to repair and grow themselves.

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