Expert: John Locke - 9/2/2009

Question
Okay, i was doing my biology homework when i came across the question, How does an organisms growth compare to the growth of an icicle? We haven't talked about icicles in class and all i now is they are made of water when it freezes. so could you please help me? How does an organisms growth compare to the growth of icicle?

Please and Thank you :)

Answer
Thanks for using AllExperts, and I apologize for the delay in replying to you.

Organisms display a number of characteristics that distinguish them as living things. You may have seen lists of these traits already in the life sciences or biology courses (organisms adapt, move, consume energy, respond to and interact with their environment, etc.); the idea here is to delineate exactly what makes organisms distinct from non-organic material. Here, we see a trait that is seemingly common to both organisms and non-organic material: growth. Both icicles and living creatures grow. They do not do so in the same manner, however, and therein lies the answer to your question.

Organisms actively search for energy sources to propagate their growth, while non-living objects do not. Animals hunt and scavenge for food, for instance; even plants will adjust the hydrostatic pressure within their stems to better angle towards the sunlight.

All organisms require sources of energy and of carbon in order to survive, while icicles require only water molecules. That fact gets at another difference: non-organic materials usually need only a few compounds in order to grow (rocks, for example, can be formed by the aggregation of only one or two minerals), while organisms much take in a large variety of nutrients in order to grow.

Non-living materials do not actively adjust their growth in response to environmental pressures, while living creatures are capable of doing so. Animals that are constantly underfed will not grow to their adult size because their brains actively decrease the energy being used for growth. An icicle adjusts its growth only passively, in that it grows when more water is present and shrinks when it does not.

Finally, icicles are crystalline structures, composed of a basic pattern repeated many times to form the object in question. Many non-living materials have such a repeating structure, and their growth is due entirely to expansion of that structure in a repeating fashion. Organisms grow by increasing the amount of various elements within themselves (cells, tissues, muscles, organs, etc.), and they do so in a non-repeating and nonuniform manner.  

If you have additional questions, please feel free to ask.