What is the importance of NAD+ cycling back up to glycolysis?

If a cell's main function is to produce proteins to be excreted, which organelles would you expect to be larger

In what for do plants utilize nitrogen? why do they need nitrogen?

How is ribosomal rna useful as a molecular clock? a. a large portion of the dna ring is not vital to structure or function, allowing it to accumulate neutral mutations. b. its rate of mutation increases over time as organisms continue to evolve and differentiate from each other. c. a slow mutation rate makes it useful for determining evolutionary relationships between ancient species. d. it is only found in select organisms, making it easier to compare relationships between species that have it.