Explanation:
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Eutrophication (from Greek eutrophos, "well-nourished") is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients. It has also been defined as a "nutrient-induced increase in phytoplankton productivity". Water bodies with very low nutrient levels are termed oligotrophic and those with moderate nutrient levels are termed mesotrophic. Advanced eutrophication may also be referred to as dystrophic and hypertrophic conditions. Eutrophication in freshwater ecosystems is almost always caused by excess phosphorus.
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Answers
When doing medical research with human subjects, the following are unavoidable limitations;
It’s often impossible to repeat trials on the same subjects.
Subjects may report an inaccurate medical history.
It can be difficult to control all possible variables
There are ethical or privacy concerns to consider.
Explanation
When doing a medical research that involves human subjects it should be voluntary, informed and consent. The researchers should respect the persons treated as autonomous agents. The volunteers should be protected from physical, mental and emotional harm. The benefits should outweigh the costs.
B.
All dentist equipment is used in the mouth. Many deseases, bacteria and viruses are transmitted trough saliva, and not all of these are weak. So, that is why we clean the dental operatory, to lower the chances of transmitting anything.
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BioTeacher101