Answer:
The cilia is one of the things that act defensively in the respiratory system.
Explanation:
It propels a mucus-like liquid that covers the airway which traps pathogens (potentially infectious microorganisms) and other particles, preventing them from reaching the lungs.
The population of blue crabs will be difficult for the scientists to count because of unreliable ways and natural phenomenon or occurrence that causes the water's temperature to rise. According to climate reports, year 1999 have warmer temperature and this probably caused the blue crabs to be active, but on year 1990 female blue crabs sustained a normal quantity of production of their species. Thus, the estimated count of population of blue crabs is probably more accurate in year 1990 than year 1999 because of the stable production of the female crabs.
The major function of the immune system is to protect the host from environmental agents such as microbes or chemicals, thereby preserving the integrity of the body. This is done by the recognition of self and response to non-self.
It could be dinosaurs, or a specific species... could you be more specific with what it's related to?