Before the three-dimensional structure of dna was discovered, scientists knew that dna contained nitrogenous bases. the table below shows the percentages of the nitrogenous bases in a dna sample. which rule can be used to determine the percentages of the missing nitrogenous bases? complete the table and explain your answer. base percent adenine 23 thymine cytosine 27 guanine

The answer is:

Adenine : 23Thymine : 23Cytosine : 27Guanine :  27

Explanation:

Chargaff's Rule:

In 1950, Erwin Chargaff proposed the Chargaff's Rule that explains the pairing and concentration of the four nitrogeneous bases in DNA. He observed that in a DNA sample, the purines and pyrimidines existed in a 1:1 ratio. This entails that in a 100 percent sample, the percentages of the bases that bond together will be equal. This means that the percentage of adenine will be equal to that of thymine. Similarly, that of guanine will be equal to cytosine.

answer: carbon 14 can only be used to determine the age of the organisms that were once living, and igneous rocks are non living.

explanation:

carbon 14 dating is used to determine the age of the sample by estimating the amount of carbon 14 present in the sample and then comparing it with a reference standard.carbon 14 is a isotope of carbon which is radioactive and unstable. carbon 14 is assimilated by all plants and animals throughout their life from carbon dioxide. however, one the organisms die they stop this assimilation and the carbon 14 content starts to decrease.by knowing how much of carbon 14 is left in an organism after his death, one can estimate the age of the organism. the materials whose age can be estimated by carbon 14 method are the organic compounds. however, some inorganic compounds such as aragonite   shell can also be dated.however, if we consider the igneous rocks it is a non living component which never accumulated carbon 14 in it and thus, we cannot use carbon 14 dating method to estimate its age.