The four limitations are
1.It's often impossible to repeat trials on the same subjects.
2-Subjects may report an inaccurate medical history.
3-It can be difficult to control all possible variables.
4-It's impossible to come up with testable scientific questions for human subjects.
Research involving human beings is ultimately necessary for improvements in human health and welfare. Any results about healthy physiology, illness causes, treatment effectiveness, learning, or behavior must be verified by carefully controlled investigations involving human participants. Sadly, not all human research have been valid and beneficial. It is possible to harm people in the name of research. The most well-known instances happened in Nazi Germany. Investigations conducted after the war found several crimes, including experiments in which participants were submerged in extremely cold water to determine how long it would take them to pass away from hypothermia.
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<span>Above human figure, beyond are approximately 5 million of hair follicles. Men have approximately a rare 100,000 larger than ladies. Something varies greatly exceedingly, the characteristices of the female hair and the men are heavy, lengthy hair and so forth.</span>
Viruses are not made out of cells, they can't keep themselves in a stable state, they don't grow, and they can't make their own energy. Even though they definitely replicate and adapt to their environment, viruses are more like androids than real living organisms.
This is false!
Carbon is found in many substances!
For example, we breathe out carbon (Carbon dioxide) and as a result, there is an amoung of carbon in the air.
Carbon is also found in many rock types, such as in coal.