Well in my words, The vaccine is the weakened or dead version of the virus(pathogen). This actually prepares the body to be un-affected if it ever comes in contact with the virus (pathogen) again. After the vaccine is injected your body produces memory cells. These help your body become immune to the same virus (pathogen) twice. So basically it helps protect your body from dangerous viruses or pathogens, and develops immunities against them.
I really hope this helped :D
Vestigial traits are adaptations to environmental pressures which are no longer present.
homologous structures are similar structures found in different species that were present in a common ancestor.
analogous traits are similar traits found in different species that were developed independently (this process is known as convergent evolution)
They tell your skin when it needs help with something.
I think the correct answer from the choices listed above is option C/ One reason that a product does not always form is due to unfavorable geometry of the reactants involved. When the geometry is not good for substances to react then no reaction can occur although there is enough energy present.
