Photo synthases is the correct answer <span />
The answer to this question would be: frequency
The higher intensity of the stimulus, the higher frequency of the action potential will be sent. The nerve can't send a higher action potential, so it firing at higher at higher intensity instead. So when you felt an intense pain, that means the pain receptor is firing more stimulus per second compared to low or mild pain.
Amino acid reactions. Amino acids via their various chemical functionalities can undergo numerous chemical reactions.
Answer:
1. mutation and genetic recombination
