Science is seldom advanced in isolation. Watson and Crick could not have arrived at their model of the helix without discovery of the structure of and how they are linked together, X-ray crystallography data, or biochemical analysis of the molar proportions of in double-stranded .

Correct question= What does the history behind the elucidation of secondary structure of DNA tell you about the role of the scientific  community in advancing science? Were Watson and Crick solely responsible?

Explanation

The earlier discovery of  nucleotide sequence and base pairing  by Levene formed the basis of  later discovery and formulation  of double Helix DNA structure by Waston and Crick. Thus Levene work contributed to  discovery  of DNA double helix structure of Waston and Crick

In addition earlier work of Franklin on X-ray crystallography data, and  comprehensive research on biochemical analysis of ,molecular proportion  of nucleotide by Chargaff, were another supporting bedrock on which Waston and Crick built their discovery of double helix structure of DNA.

Evidently most scientific discoveries were usually  arrived at from the earlier  work or discoveries,  and rarely in isolation.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation: