In the 1800s, scientists studied how fat-soluble substances and water-soluble substances interact with cell membranes. Their studies provided evidence that cell membranes are structured to perform certain functions. What function did these studies suggest that cell membranes
perform?
carry materials throughout the interior of the cell
control the cell's activities
control which substances enter the cell
form proteins from fat-soluble substances

control which substances enter the cell

Explanation:

According to this question, scientists in year 1800s studied how fat-soluble substances and water-soluble substances interact with cell membranes. Cell membrane is a cellular structure found in every living cell whose function is to demarcate the interior of the cell from the external environment.

Based on the study, cell membrane interacts with water-soluble and fat-soluble substances in order to control which substances can enter the cell. The cell membrane is selectively permeable meaning that not all substances passes through it into and out of the cell.

Student 1’s methods would be more accurate, because the student would control more factors. Only one variable at a time (either temperature or acidity) would be tested on each group of worms. On the other hand, Student 2 is testing both factors on all the worms, which could make the results unclear.