In the following data table of an experiment carried out at 4°C (39.2 F) over 4 hours
Solution in bag
Solution outside bag
Bag mass change (g):
water
Water
-0.2
20% sucrose
Water
+2.4
, 40% sucrose
Water
+4.3
, 60% sucrose
water
+5.8
Which of the following options represents the dependent variable?
A.
Duration
B.
Temperature
C.
Bag mass change
D.
Sucrose concentrations.
The correct answer and Explanation is :
The correct answer is C. Bag mass change.
In any scientific experiment, variables are classified into independent and dependent categories. The independent variable is the one that is manipulated or changed by the experimenter, while the dependent variable is the one that is measured or observed as a response to the changes made.
In this experiment, the independent variables include the sucrose concentrations of the solutions outside the bag (20%, 40%, and 60% sucrose) and the duration of the experiment, which is set at 4 hours. The temperature is also controlled at 4°C, ensuring that it remains constant throughout the experiment.
The dependent variable, on the other hand, is the bag mass change (measured in grams). This variable is dependent on the osmotic effects of the sucrose concentrations in the external solutions. As sucrose concentration outside the bag increases, it affects the movement of water across the semipermeable membrane of the bag. Water moves from an area of lower solute concentration (inside the bag) to an area of higher solute concentration (outside the bag) through osmosis. Consequently, this movement alters the mass of the bag, which is what is being recorded and analyzed in the experiment.
The mass change is a direct measurement of the osmotic activity occurring due to the varying sucrose concentrations. The results indicate how much water was drawn out of the bag or retained within it, providing insights into the osmotic behavior of solutions with different solute concentrations. Thus, the bag mass change is the key response variable that reflects the effects of the independent variables manipulated during the experiment.