What are major characteristics of living things?

Answer 1

The main characteristics of living things can include:

1. A first characteristic of living things is that they respond to stimuli, a concept known as irritability. They are irritable in that they respond to their environment. Nonliving systems show this same characteristic. Ans electric eye responds to breaking a beam of light by opening a door. A switch responds to stimulus by turning on a light for us. The responses of living things, however, usually are related to their own well being.
2. A second characteristic of living things is that they are highly organized. Any simplicity is deceptive. The protozoa, for example, are not simple organisms but are highly complex. Their cells are more complex than the cells of multi-cellular organisms since they are capable of carrying on all the activities of living things, whereas the specialized cells of a higher organism can carry only one or at most a few activities.
3. The third is that living things metabolize. They take in foods that serve as sources of energy and combine these materials with oxygen, releasing the energy and giving off waste products. A gasoline engine is similar. It takes in the fuel, oxidizes it, and gives off waste products, but in simpler reactions than those of living things.
4. A fourth characteristic of living things is that they grow. The excess of the energy-building materials (i.e., food) not needed for metabolism is used to provide additional protoplasm (an important cellular substance). But nonliving systems also grow. A cloud grows in size. Rocks increase in size. In general, nonliving systems grow by accretion, that is, by adding of materials to the outside. Living systems grow by intussusception, growth from within, taking in food and changing it into living tissue.
5. A fifth characteristic of living things is that they reproduce. The excess energy not needed for metabolism or growth is used to produce additional organisms. Nothing smaller or simpler than a living cell has been known to reproduce itself. The idea that life only arises from life is called biogenesis.

If you want the answers, just look at the words in italic, but it would help benefit you more if you read the whole thing. I hope this is what you are looking for.

Copyright © 2004 by Christian Liberty Press

Biology: A Search for Order in Complexity, Second Edition

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Christian Liberty Press

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Editors: Leslie Mackenzie, B.S., M.S.

David K. Arwine, D.S., M.S.

Edward J. Shewan, D.S., M.Div.

Michael J. McHugh, B.S.

Copyediting: Diane C. Olson

ISBN 978-1-930367-92-0