The dense, round structures in the micrograph above are cells of one hazardous phytoplankton species present in 250ml of water sample.
(a) How many of these cells are present in this sample?
(b) What is the number of cells of this phytoplankton per litre of water?
(c) For this phytoplankton, 100 cells/Litre is a “trigger” value for indicating whether the water is hazardous. Does this sample exceed this “trigger” value?
We don not have the micrograph. Let us use the 24 cells in 250 ml as the number of phytoplankton cells.
(a) 24 cells are present in this sample
(b) "24 \\times 4 = 96" cells per litre of water
(c) This sample does not exceed the “trigger” value