by experimenting the layers of the earth
Answer:
HYDRA
Explanation:
The nerve cells are scattered in each layer of the body wall and these neurons send information from sensory organs. Based on the given choices above, the organism that has a nerve net that allows it to respond to a stimulus in a coordinated way is the HYDRA.
It is is by digestion of complex molecules into simpler forms lke carbohydrates into its corresponding monosacchrides Glucose.Proteins to amino acids, Lipids to fatty acids and nuclec acids to nuclotides respectively.it is nothing but the metabolism of the complex macromolecules that we consume in the form of food.