Certain vaccines are live which means they are putting the actual virus into the patient thought the injection. This means people who are immune compromised can’t have these because they will get very sick. This is the only way I know how to answer
So that they don't explode.
AKA with a thing called osmosis (transportation of water through cells.)
True
Hormones released by the endocrine system travel in the blood until they find their specific target cell it is true.
hope this helps!
Tectonic plate movements, volcanic eruptions, earthquakes, and climate change have shifted wildlife habitats, wiped out large numbers of species, and created opportunities for the evolution of new species. Hope this helped!