The answer is protect the body from infection by pathogens
The physical barrier is made of epithelial cells, mostly will be keratinized to increase their sturdiness further. They will impede the pathogen physically by barricading the cells, makes the pathogen could not invade deeper part of the body. Histamine and antibodies should be the role of immune cells, not epithelial.
We could say that there are five steps in scientific method: observation, hypothesis, prediction, experiment and conclusion. Observation is the first step and we could also call it research. In this step we must understand the problem in the right way. The hypothesis is the possible answer, based on the research. Prediction is even more specific than the hypothesis: on this stage, you must know how will you demonstrate that your hypothesis is true. Experiment tests your hypothesis and shows whether your hypothesis was true or false. After that you can proceed to making conclusion, which summarizes the experiment's results, and tells do the results match up to hypothesis and in which way.
Answer:
1. Electric current decreases as more
devices are added to a(n) _a_ circuit
,
cyclins are proteins that regulate the time of the cell cycle in eukaryotic cells.
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