B. trenches .......................
If a cell’s nucleus has 55% adenine bases it also has 55% thymine bases, so the percentage of cytosine bases is 45% as same as guanine bases.
This is known as Chargaff's rule which states that DNA should have a 1:1 ratio of pyrimidine and purine bases (the amount of guanine should be equal to cytosine and the same thing with adenine and thymine).
DNA molecule globally has percentage base pair equality: %A = %T and %G = %C.
Answer is: the part of an experiment that stays the same though out the experiment is constant.
<span>Constant is a quantity that does not change.
</span>Experimental variable<span>, which is the also part of an experiment, is affected by the experiment (have change).</span>
If the paramecium was not able to contract its contractile vacuole, it would be in danger of bursting. The cell would not be able to hold too much water. This would happen faster if the paramecium was in water with a low salt concentration because there is more water and less salt, so the water would accumulate faster.