In 1953, who developed the model that is shown below? james watson and francis crick marshall nirenberg and heinrich matthaei rosalind franklin erwin chargaff

The right answer is James Watson and Francis Crick.

On April 25, 1953, Francis Crick and James Watson described for the first time in a study the structure of DNA (deoxyribonucleic acid), a molecule in the form of a double helix containing the genetic heritage of all life forms. It was with a single-page article published in the British scientific journal Nature that the two young researchers (Crick was 36 years old and Watson only 25) would upset the world of biology and genetics.

At the time, we already know DNA and, even if some scientists have had trouble accepting it, we know that it is the support of heredity. Studies have also already specified its chemical nature: a combination of nucleotides (phosphate - deoxyribose - nitrogenous base), assembled in long chains.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

lipid

explanation: