Which activities? I want to say the nucleus as it is the control center of the cell, but this is a vague question.
Explanation:
protect cells and organelles from the surrounding environment
Insect Compound Eye vs. Human Eye. Insects and humans have very different types of eyes, but each has advantages and disadvantages. ... The quality of its vision is much higher than that of a compound eye, and it has a much more complex construction
Energy would have to be the correct answer
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>
