Answer: congelar el agua.
Explanation: un fenómeno físico se produce cuando el cambio no es muy profundo y no altera la naturaleza química.
Answer: Acetylcholine.
Explanation: Acetylcholine is a neurotransmitter that mediates many sinaptic functions in nervous system. When a motor neuron releases acetylcholine at the neuromuscular junction, it binds to nicotinic receptors in muscular fibers and activates a signal cascade that will free intracellular calcium ions, causing the contraction of the muscular fibers.
Fossils can be classified by their morphology (how they look), ethologically (how they acted), and toponomically (where they are in the substrate layers) to produce phylogenetic trees. However, more recent advances in genetic technology allow us to extract DNA from more recent fossils that have not had too much breakdown of the DNA, and we can much more accurately classify species from that information, and also provide much more accurate phylogenetic analysis.
A sharp, stinging odor would most likely be a defense mechanism for a plant.
