What are the three pressures that lead to biodiversity

Ectocarpene is a volatile, sperm cell-attracting material released by the eggs of the seaweed ectocarpus siliculosus. its constitution is all the double bonds are cis, and the absolute configuration of the chirality center is s. draw a stereochemically accurate representation of ectocarpene.

Which would be the most useful source of evidence to support mcneill's contention?

Which of these is not a nucleotide base found in dna?