A portal of entry<span> is the site through which micro-organisms enter the susceptible host and cause disease/infection. Infectious agents enter the body through various </span>portals<span>, including the mucous membranes, the skin, the respiratory and the gastrointestinal tracts.</span>
A. community and abiotic environment
The ecosystem will collapse and fail because every species are needed and play a role in the ecosystem.
The gravity from the moon and some from the sun brings the tides up, because the moon's gravitational force is strong enough to pull some water up.
