You should immediately realize that this is a question about cellular respiration. You should draw on your knowledge of this topic to answer the question. Use the organism that you used when completing this lab (commonly germinating peas).
(A) Key points to include: the organism you chose, clear identification of the experimental variable, clear explanation for the variables that you must control, an explanation of the apparatus that you will use to measure the cellular respiration
Here is a possible response:
Cellular respiration can most easily be measured by consumption of O2 or by the production of CO2. In this experiment, the volume of O2 consumed by germinating peas will be measured. The experiment will test peas that have been germinating one day vs. peas that have been germinating for three days. Therefore, the number of days the peas have been germinating will be my experimental variable. I will use an apparatus called a respirometer to measure the amount of O2 consumed. This device will be submerged underwater with a pipette attached to the end. I will be able to measure the amount of water drawn into the pipette by comparing where the water mark begins and where it ends. I will eliminate the production of CO2 as a variable by using potassium hydroxide (KOH) to fix CO2 into a solid form: potassium carbonate (K2CO3). KOH will be added to an absorbent cotton ball and placed on the bottom of the respirometer with a non-absorbent cotton ball in between, so the KOH will not interfere with the experiment. Because volume must be controlled, I will use glass beads to control the volume differences between the two germinating pea samples.
I will place each respirometer in the same tub of water to control temperature between the two germinating pea samples.
Hypothesis: Measuring cellular respiration for 30 minutes at intervals of 10 minutes at a time will demonstrate that peas that have been germinating for three days will consume more oxygen through cellular respiration than peas that have been germinating one day.
Procedure: I will place 20 peas that have been germinating for one day in one respirometer and 20 peas that have been germinating for three days in another respirometer. After a 10-minute equilibration period, I will begin to measure the amount of oxygen consumed at 10-minute intervals for 30 minutes. I will record results measured by the graduated intervals on the pipette attached to the respirometer.
(B) Key points to include: labels on each axis, regular intervals on the graph, a specific title on the graph, points plotted on the graph, and a line connecting the appropriate points. If there is more than one plot on the graph, you should use a dotted line for one line and a solid line for the other. Alternatively, you can simply write a short phrase above each line for identification.
Here is a sample graph:
(C) Key points to include: clear explanation of the graph and clear explanation of the significance of the results
Here is a possible response:
The graph shows that peas that have been germinating for three days consume more oxygen during a 30-minute period than peas that have been germinating for one day. The peas that have only been germinating for one day are not as well developed. Therefore, these peas are not undergoing as much cellular respiration as the more developed peas that have been germinating for three days.
Learn More About the Haiku Deck Below
The words and images in the deck above are meant to guide students as they prepare for the AP Biology Exam. The words were chosen based on their emphasis in the AP Biology Curriculum Framework and/or their history of appearing on previous exams. This work builds upon the contributions of many great science teachers. Attributions are listed at the end.
Tips for Answering AP Biology Free Response Questions
It may come as no surprise that many students struggle with answering the free response questions on the AP Biology test. One possible reason is that they don’t know the answer. A less obvious reason is that they don’t understand the question. I’ve read lots of answers to lots of FRQs and I’m surprised how often students miss points for not fully addressing the question. So, if you’re a student, I don’t want you to make the same mistake. Please read carefully.
The good news is that a poor understanding of the question is easy to fix. The free response questions on the AP Biology Test are going to tell you exactly what you need to write. Take a look at a portion of a free response question from the 2012 AP Biology test.
Explain TWO unique properties of human embryonic stem cells that distinguish them from other human cell types. Describe a current medical application of human stem cell research.
Let’s break this down.
Q. How many unique properties of human embryonic stem cells do you need to address?
Q. What must you do with these properties?
A. You must explain or describe them
Q. What does distinguish mean?
A. It means, “to show the difference between two or more things,” so you’re describing something a stem cell can do that a non-stem cell can’t.
Q. What must you do with a current medical application of human stem cell research?
A. You must describe it.
It seems so obvious when you break it down like this. The exam writers even bold key verbs and use all-caps to specify quantities. These questions get straight to the point, and so should you’re answers. There are lots of important details in those little sentences. Read them carefully. It really bothers me when students miss points because they glossed over the details. I know they can do better than this and so can you.
On exam day, the College Board is going to give you some last-minute words of advice. But, wouldn’t you rather hear these words now? Listen to what they say. The Free Response Booklet Instructions state the following:
Each answer should be written out in paragraph form; outline form is not acceptable. Do not spend time restating the questions or providing more than the number of examples called for. For instance, if a question calls for two examples, you can earn credit only for the first two examples that you provide. Labeled diagrams may be used to supplement discussion, but unless specifically called for by the question, a diagram alone will not receive credit. Write clearly and legibly. Begin each answer on a new page. Do not skip lines. Cross out any errors you make; crossed-out work will not be scored.
The free response portion of the AP Biology Exam is 90 minutes long. However, you are advised to spend the first 10 minutes reading the questions and planning your responses. Next to each question is an unlined, blank area called a “planning space.” This area is provided for making notes, outlines, diagrams, or whatever else you need to craft your answers. The Free Response Booklet Instructions state the following:
The proctor will announce the beginning and end of the reading period. You are advised to spend the 10-minute period reading all the questions, and to use the unlined pages to sketch graphs, make notes, and plan your answers. Do NOT begin writing on the lined pages until the proctor tells you to do so.
Think about what they’re saying, take these words to heart. Don’t jump in and start writing until you’re sure of what’s being asked of you. It’s easy to miss the subtle nuances of a question prompt. Slow down. Ten minutes will seem like a long time, but what if you waste twenty-two minutes because you didn’t fully digest the question?
There are a total of eight free response questions in section II of the AP Biology Exam, which account for 50% of your total exam score. The table below indicates the specifications for each question.
|Question Number||Question Style||Point Value||ApproximateWeight||Suggested Minutes to Complete|
If you haven’t seen it already, you should become familiar with the AP Biology – Section II Free-Response Booklet. This document gives you a diagram for how the free response section will be laid out.
AP Biology – Section II Free-Response Booklet
Hopefully these tips for answering AP Biology free response questions will reduce your anxiety and boost your confidence. Knowing the layout and specifications of the items and the meaning of commonly used “power words” ahead of time will allow you to focus on what’s most important: communicating what you actually know.
Have questions about the Do’s and Don’ts of filling in the Grid-In question? Check out my post:
How to Answer the Grid-In Response on the AP Biology Test
I hold a Master of Arts in Teaching degree and have been teaching science in public schools since 2004. I have a love for biology and instructional design. My mission is to share with other educators the best of what I know about teaching.