some macroinverebrates like mayflies are sensitive to pollution or low dissolved oxygen. if these organisms are present, then the stream can be considered a healthy stream. mayflies would be considered a(n)

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.