In 1953, Watson and Crick were able to propose a model of DNA as a helical molecule with a sugar-phosphate backbone on the outside of the molecule. Which of the following earlier discoveries was most instrumental to this important discovery? By studying this photograph, scientists gained knowledge about the —
A. the discovery by Hershey and Chase that only DNA from a virus need enter a bacterial cell to cause an infection
B. X-ray crystallography studies of DNA conducted by Rosalind Franklin in 1951
C. the identification of DNA as the agent of bacterial transformation by Oswald Avery
D. the 1948 discovery by Linus Pauling that proteins take the shape of an alpha helix

When does the circulatory system work with the respiratory system? a. during blood cell formation b. during cellular respiration c. during intestinal digestion d. during a viral infection

Nhumans, abo blood types refer to glycoproteins in the membranes of red blood cells. there are three alleles for this autosomal gene: ia, ib, and i. the ia allele codes for the a glycoprotein, the ib allele codes for the b glycoprotein, and the i allele doesn't code for any membrane glycoprotein. ia and ib are codominant, and i is recessive to both ia and ib. people with type a blood have the genotypes iaia or iai, people with type b blood are ibib or ibi, people with type ab blood are iaib, and people with type o blood are ii. if a woman with type ab blood marries a man with type o blood, which of the following blood types could their children possibly have? in humans, abo blood types refer to glycoproteins in the membranes of red blood cells. there are three alleles for this autosomal gene: ia, ib, and i. the ia allele codes for the a glycoprotein, the ib allele codes for the b glycoprotein, and the i allele doesn't code for any membrane glycoprotein. ia and ib are codominant, and i is recessive to both ia and ib. people with type a blood have the genotypes iaia or iai, people with type b blood are ibib or ibi, people with type ab blood are iaib, and people with type o blood are ii. if a woman with type ab blood marries a man with type o blood, which of the following blood types could their children possibly have? a, b, ab, and o ab and o a, b, and o a and b

What are levels of ecology and how can we remember them