Answer:
A vaccine activates our immune system without making us sick. Many dangerous infectious diseases can be prevented in this simple and uncostful
drug .Vaccines have eliminated some of the most dangerous, fatal diseases in human history.
Answer:
The ecosystem would be forced to radically change, allowing new and possibly invasive species to populate the habitat.
Explanation:
A keystone species is an organism that helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether.
I HoPe ThIs HeLpS!!!!!
B. The nervous system collects and responds to information about the external and internal environment.
The first heart chamber that the dye would enter is right atrium.
This will be followed by
left ventricle
right ventricle
left atrium
coronary valve