Answer:
b. Nucleotides  
Explanation:
Nucleic acids are examples of structures formed from nucleotides. And in relation to the composition of DNA, we have the formation of the largest cellular macromolecule, all formed by nucleotides.
The nucleotide is a group formed by the association of 3 molecules - a nitrogen base, a phosphate group and a pentose glycide. Thus, we may have variations within these ligands, such as: in DNA we have the presence of pentose deoxyribose, while in RNA we have the presence of pentose ribose.
The nucleotides have differences in relation to its nitrogen base, which can be purine or pyrimidine. Purine bases vary in Adenine and Guanine, while pyrimidine bases are classified in Thymine, Uracil and Cytosine. Purine and pyrimidine bases are complementary and each have specific binders. Thus, we have that the purine base Adenina, binds with the pyrimidine bases Timina and Uracila, while the base Guanina binds exclusively to Cytosine and vice versa.
 
        
             
        
        
        
Yes, as scientists could figure out what might have changed in the variables she used. Brainliest me and I can give you the whole system.
        
                    
             
        
        
        
Answer:
From Hydrogen ion.
H+
Explanation:
It's is from hydrogen ion because majoroty of the electrons transport processes take place in the thylakoids membranes in a bid to produced ATP, Hydrogen ion is allow to move through thylakoid space and then backflow through the proteins embedded in the thylakoids membrane called ATP synthase, which produce ATP from ADP in the mitochondrial matrix and chloroplast stroma.