B. are more difficult to control than point sources. This is because A. is wrong (point source), and C. is wrong, because it doesn't necessarily cost less or more to identify the sources. D. may be right, as non point sources are natural, such as snow melts or rain.
It's letter C. Multicellular, eukaryotic, heterotrophic
Answer:
A) purine
Explanation:
There are two ways for the synthesis of purines and pyrimidines:
- de novo synthesis-from basic simple units
- "recycling" synthesis-reuse of metabolites
Purines are synthesized directly on ribose sugar, in segments.
Pyrimidines are attached to the ribose after the synthesis of the base.
5-Phosphoribosyl-1-pyrophosphate (PRPP). is used for the synthesis of purine (ribose 5-phosphate reacts with ATP to form ribonucleotide).