Hormones are chemicals released into the bloodstream by the endocrine glands chemicals found in the synaptic vesicles, which when released, have an effect on the next cell chemicals found in the soma, which when released, have an effect on the next cell chemicals released into the bloodstream by the brain

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

answer: accepted answer: aquatic animals use the oxygen dissolved in water to carry out respiration. since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore the rate of breathing in aquatic animals is much faster than it is in terrestrial animals.

explanation:

the answer is: metamorphic rocks often show the presence of fossils, also a

hope i

-lavira: )