Question

Select two items that biologists agree are necessary in order to consider an organism “alive.” For each, give an example of a nonliving object that otherwise fits the definition of “alive.”

Answer 1

Answer:

Cellular organization and metabolism are two items necessary to consider an organism alive.

Explanation:

There are certain characteristics that belong to living beings and that they all have in common. These are distinctive characteristics that do not include any non-living object. Among others, we can name the followings:

1) Precise cellular organization. The cellular theory states that every living being is conformed of basic units named cells and their products that result from the cellular activity. Although organisms vary in size and shape, all of them are formed by cells. A cell is the simplest part of the living matter which is capable of performing every necessary activity needed for life. Some of the simplest organisms, such as bacterias or some algae, are unicellular. This unique cell must be polyfunctional, as it has to perform many activities. On the other hand, many other organisms are highly complex pluricellular. All the processes of the entire organism depend on the correct and coordinated functioning of every constituting cell. The more complex the organism is, the more specialized are the cells, differentiating from each other, and acquiring certain specific functions. These are, for example, the epidermic cells, muscular cells, nervous cells, reproductive cells, among others.

2) Metabolism. In any living being there happen many essential chemical reactions needed for appropriate nutrition, growth,  cellular repairing,  energy conversion, among others. All of these chemical reactions in the organisms are known as metabolism. These cellular activities begin when the organism takes life, and continue through its whole life. When chemical reactions stop, the organisms might be considered to be dead. Every specific cell in the organisms take substances that chemically modify, in many different ways, to integrate new cellular components.  Some of these nutrients are used in cellular respiration. During this process, part of the energy stored is taken by the cell for its own use.  This energy is also needed for synthesis and other cellular activities. In most organisms, cellular respiration requires oxygen provided by the gas interchange. Cellular wastes, such as carbon dioxide and water must be eliminated from the organism. Every chemical reaction is regulated by specific enzymes.