Are lipids that serve as chemical messengers. a
RNAs
b
Enzymes
C Steroids
d Proteins
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How can a geological time scale best be reconstructed? a) comparing vestigial structures in living species b) comparing homologous structures in living species c) examining homologous structures in fossil remains d) examining the written records of scientists from past cultures

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above

How does food concentration affect yeast activity