How did watson and crick determine base pairing?
a. they analyzed the work of phoebus levene.
b. they used chargaff's rule to fit the bases together.
c. they broke the hydrogen bond.
d. they observed the pairing under a microscope.

Watson and Crick determined base pairing by using Chargaff's rule to fit the bases together.

Further Explanation Watson and Crick discovered that the DNA strands exists as a double helix, which appears like a twisted ladder.  In doing so, Watson and Crick used the Chargaff’s rule to confirm the base pairing in the double stranded DNA, so as to fit the complementary bases together. Structure of DNADNA is a nucleic acid that carries genetic material in all living organisms. DNA is a double stranded nucleic acid whose building blocks are known as nucleotides. Each nucleotide contains a sugar, a phosphate group and a nitrogenous base. The four nucleotide bases found in the DNA are Adenine, Cytosine, Thymine and Guanine. The strands of DNA are attached to each other as a result of base pairing that occurs through hydrogen bonding as explained by Chargaff’s rule. Chargaff’s rule. Chargaff’s rule describes the base pairing in a DNA molecule, such that the base Guanine pairs with the base Cytosine in the complementary strand, while the base Adenine pairs with Thymine. This means the number of thymine bases in a DNA molecule will be equal to the number of Adenine bases, while Guanine bases will be equal to Cytosine bases. The result is a ratio of 1:1 between pyrimidines and purines in a molecule of DNA. Chargaff's rule of base pairing provided Watson and Crick with a prove that their model was correct, since it agreed with Chargaff's as far as the percentages of A,T,G, and C in DNA are concerned.  According to Watson and Crick model, the hydrogen bonds could only form between adenine and thymine, and between cytosine and guanine to create an almost perfect fit.  

Keywords; Watson and crick model, Chargaff’s rule, DNA, and base pairing.

Learn more about; DNA and its structure; link Watson and crick model; link

Level; High school

Subject; Biology

Topic; Nucleic acids  

Sub-topic: DNA structure and base pairing.

In fact it is not just nuclear fusion and fission that  can  transform  matter  (or mass)into energy. any time  energy  is produced, some small amount of  matter  or mass isconverted into energy.