The SAT II Chemistry uses group questions based on experiments, biological situations, and data to measure your scientific reasoning and laboratory skills. There is no standard appearance for the experiments; the data can be presented in paragraphs, tables, and/or graphs.
These groups can be the most intimidating part of the SAT II Chemistry test: they often describe scenarios that are more complex or advanced than what you’ve been exposed to in Chemistry class or labs. But stay confident: the two main purposes of these group questions are to test how you understand scientific data and how you apply knowledge of biological principles to this data. Any unfamiliar terms or experimental techniques mentioned in the groups usually just mask simple concepts addressed by the individual questions. In fact, some questions might simply ask you to interpret the data. For these questions you won’t have to think much about the concept at all.
Questions 8–10 refer to the following experiment and results obtained.
Dialysis bags are semipermeable membranes, allowing the transport of small molecules while prohibiting larger ones. In an experiment, students filled dialysis bags with different concentrations of sucrose solution and placed them in a beaker of distilled water. The bags were each weighed before being placed in the beaker. After two minutes, they were removed from the beaker, dried, and weighed again.
8 - Which dialysis bag experiences the largest percent change in mass?
- 0.2 M sucrose
- 0.4 M sucrose
- 0.6 M sucrose
- 0.8 M sucrose
- 1.0 M sucrose
9 - If the 0.6 M sucrose solution bag was left in the beaker for four minutes, all of the following occur EXCEPT
- mass of the dialysis bag increases to more than 30.1 g
- water travels down its concentration gradient
- decrease in the bag’s molarity of sucrose
- sucrose leaks into the beaker
- volume of water in the beaker decreases
10 - A glucose molecule is small enough to pass through the bag. If glucose was substituted for sucrose in the dialysis experiment above, by what process does it cross the membrane?
- Osmosis
- Active transport
- Simple diffusion
- Facilitated diffusion
- Transpiration
For each experiment, identify the following: What is being tested and why? What are the variables, and what factors stay the same? In this example, the mass of the dialysis bags changes with the variable of sucrose concentration. Changes in mass can only come from water entering or leaving the bags, so the question deals with osmosis. (You’ll learn all about osmosis, diffusion, and transport over membranes in the chapter covering the cell.)
The three sample questions are good examples of the various types of questions the SAT II Chemistry asks in experiment groups. You don’t have to know anything about concentrations, osmosis, or membrane transport to answer the first question in this group; determining percent change in mass demands only simple data interpretation. The second question requires you to extrapolate and make predictions from the data. The third question asks you to make predictions on what would occur if the experiment were slightly modified. This last type of question goes beyond the numbers and requires knowledge of the topic. If you can identify the general biological properties of the experiment in advance, you should have no trouble answering questions of this sort. The answers to the above sample questions are: 8 D, 9 D, and 10 C.
The SAT II Chemistry may also present data in graph form. For graphs, make sure you know what the axes represent. Think about what relationship exists between these concepts and identify in advance any general trends you can think of. If it helps, sketch out your own tables or notes to sort the data and identify trends or exceptions. For all experiment-based questions, elimination is a helpful tool. You can eliminate answer choices that do not relate to the experiment’s variables or what is being tested, or those choices that contradict your knowledge of the biological principles working in the experiment or scenario.