and bases are chemicals that are produced
and used by organisms in your biotic community. One way you can tell
if an organism produces an acid or base is to eat it. Foods that
contain bases taste bitter. Foods that contain acids taste sour.
Did you ever eat a lemon? Even you produce acid. Its called
hydrochloric acid, and its found in your stomach. Ammonia is a base,
and many animals secrete this in their wastes. Fish do this, and
so the level of ammonia in their tank must always be monitored. In
fact, the level of acid or base in the soil and water or your biotic community
is extremely important to the organisms that use the soil and water.
This means all of the organisms!. This is why you should know
the level of acids or bases in the water and soil of your community.
You can measure how much acid or base there is in the water or soil. A measuring scale has been developed to do this. It is called the pH scale.
The numbers of this scale range from 1 to 14. Numbers greater than 7 represent an acid environment. Numbers below 7 represent a basic environment. Pure water contains no added acids or bases. This condition is called neutral, and the pH number would be exactly 7. As you might imgine, most organisms like the pH of their environment to be in the neutral range. They prefer the pH to be 7. Unfortunately, many chemicals can cause the pH to go up or down and not stay neutral. Since the organisms in your biotic community depend on the water, this would not be a good situation for most organisms. This is the reason why the pH is so important for the organisms of your community.
There is an easy way for you to measure pH. You will use a strip of paper that contains chemicals called indicators. Indicators change color when they come in contact with acids or bases. This means that the paper will change color when it touches an acid or base. The color scale will show you what color matches what pH. You will use pH paper to determine the pH of the soil and water of your biotic community.