<span>Controlled experiment is an experiment done under controlled conditions in which only one variable at a time is changed in order to isolate the results. An alternative to a controlled experiment would be a correlation study. A correlation study is a research method in which two variables are compared (what are the similarities and the difference between them). So, correlation study is a type of controlled experiment in which ove variable is changed and the dependence with another variable is analyzed.</span><span />
Answer
<em>According to ThoughtCo,</em>
<em>The cell membrane (plasma membrane) is a thin semi-permeable membrane that surrounds the cytoplasm of a cell. Its function is to protect the integrity of the interior of the cell by allowing certain substances into the cell while keeping other substances out.</em>
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<em>Hope this helps! <3</em>
