What are the four major classes of molecular building blocks found in living organisms? Give a specific example of each What are three physical differences between prokaryotes and eukaryotes? What substances are used during photosynthesis? What substances are produced during photosynthesis? What substances are produced during cellular respiration? State two differences between aerobic and anaerobic respiration. Select one aspect of cancer and discuss. What is a Karyotype? List one way in which it may be used.