An orgainism is endangered when it is close to extinction...this happens when an organism is hunted down for its meat or other properties...
The answer for this question would be Integument, digestive, respiratory and urogenital.
The largest system that contact with the external environment would be integument and digestive. That makes two system has normal flora of microbes and not sterile like the other systems. Normal flora of microbes will prevent the pathogen microbe grows so it gives some benefit.
<span>The correct answer is the chromatin. The chromosomes of all organisms, excluding bacteria, are made of chromatin. Chromatin is a group of macromolecules consisting of RNA, DNA, and protein.</span>
The answer is hydrogen bond between the complementary strands.
