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>By filtering the air so that the lungs so the lungs don't get infected</span>
Answer:
Organisms use camouflage to mask their location, identity, and movement. This allows prey to avoid predators, and for predators to sneak up on prey. ... The physical characteristics of the organism are important. Animals with fur rely on different camouflage tactics than those with feathers or scales, for instance.
Explanation:
<span>neural activity -APEX</span>
Answer:
there were only anaerobic heterotrophic bacteria (the primordial atmosphere was virtually oxygen-free).
