At the end of which period on the geological time scale did the dinosaurs become extinct? a. jurassic b. quaternary c. cretaceous d. tertiary

What links the two strands in a dna helix together in the middle? a. phosphate groups b. sugar rings bonded together c. proteins d. bases with hydrogen bonds

What is one function of the embedded proteins

Explain how the political influence of african americans leaders became weaker.