Because secondary sucession has bas soil that is intact still unlike primary sucession which begins with virtually lifless area without soil
To make Paramecium Contractile vacuole concentration graph useful the salt concentrations descriptions should replaced with actual values.
Thus, option "A" is correct.
What is Paramecium Contractile vacuole
"It is a sub-cellular structure (organelle) involved in osmoregulation."
<h3>What is a graph?</h3>
"A diagram (such as a series of one or more points, lines, line segments, curves, or areas) that represents the variation of a variable in comparison with that of one or more other variables."
<h3>What does the graph in the given question depict?</h3>
It shows that the Paramecium Contractile Vacuole concentration per minute decreases as salt concentration increases.
But the concentration of salt is not mention in quantity so its not clear what are the lowest and highest concentration affecting Paramecium Contractile Vacuole.
Hence, the Paramecium Contractile Vacuole concentration graph can be more useful if the actual values of salt concentration will be mentioned.
To know more about Paramecium Contractile Vacuole here
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The heart’s electrical system is responsible for making and conducting signals that trigger the heart to beat. These signals cause the heart’s muscle to contract. With each contraction, blood is pumped throughout the body. This happens 24/7 without us having to monitor it all the time so that our heart does not stop.