AP® Biology Scoring Guidelines

AP® Biology Scoring Guidelines

AP Biology 2021 Scoring Guidelines provide detailed evaluation criteria for the AP Biology exam, focusing on experimental results, data interpretation, and scientific investigation. This resource is essential for AP Biology students preparing for the exam, offering insights into scoring rubrics and sample responses. Key topics include cell biology, genetics, and ecological principles, with specific guidelines for each question type. Students can use these guidelines to understand how to effectively communicate their scientific reasoning and analysis during the exam.

Key Points

  • Includes scoring criteria for AP Biology exam questions.
  • Covers experimental design, data interpretation, and scientific reasoning.
  • Provides sample answers to illustrate high-scoring responses.
  • Focuses on key biological concepts relevant to the AP curriculum.
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2021
AP
®
Biology
Scoring Guidelines
© 2021 College Board. College Board, Advanced Placement, AP, AP Central, and the acorn logo are registered
trademarks of College Board. Visit College Board on the web: collegeboard.org.
AP Central is the official online home for the AP Program: apcentral.collegeboard.org.
AP® Biology 2021 Scoring Guidelines
Question 1: Interpreting and Evaluating Experimental Results 10 points
Polycystic kidney disease (PKD) is an inherited disease that causes water loss from the body and affects cell
division in the kidneys. Because water movement across cell membranes is related to ion movement, scientists
investigated the role of the
Na
+
/K
+
ATPase
(also known as the sodium/potassium pump) in this disease.
Ouabain, a steroid hormone, binds to the
+ +
Na /K ATPase
in plasma membranes. Individuals with PKD have a
genetic
mutation that
results in an increased binding of ouabain to the
+ +
Na /K ATPase
. The scientists treated
normal human kidney (NHK) cells and PKD cells with increasing concentrations of ouabain and measured the
number of cells (Figure 1)
and the activity of
the
+ +
Na /K ATPase
(Figure 2) after a period of time. The
scientists hypothesized that a signal transduction pathway that includes the protein kinases MEK and ERK
(Figure 3) may play a role in PKD symptoms.
Figure 1. Cell number compared with the number of
cells at
0 pM
ouabain. Normal human kidney
(NHK) cells and polycystic kidney disease (PKD)
cells were treated with increasing concentrations of
ouabain. Error bars represent
2SE
X
±
.
Figure 2. Percent
+ +
Na /K ATPase
activity of NHK
and PKD cells treated with increasing concentrations
of ouabain. Error bars represent
2SE
X
±
.
Figure 3. Signal transduction pathway hypothesized to play a role in the increased number of PKD cells
© 2021 College Board
AP® Biology 2021 Scoring Guidelines
(a)
Describe the characteristics of the plasma membrane that prevent simple diffusion of
Na
+
and
K
+
across the membrane.
1 point
Accept one of the following:
• The interior of the plasma membrane is hydrophobic/nonpolar.
• The phospholipid tails are hydrophobic/nonpolar.
• The exterior of the pla
sma membrane is hydrophilic/polar.
• The phospholipid heads are hydrophilic/polar.
Explain why ATP is required for the activity of the
+ +
Na /K ATPase
.
1 point
• The
+ +
Na /K ATPase
pumps ions against their concentration gradients. This requires
an input of (metabolic) energy.
Total for part (a) 2 points
(b) Identify a dependent variable in the experiment represented in Figure
1. 1 point
• The number of cells
Justify the use of normal human kidney NHK cells as a control in the experiments. 1 point
Accept one of the following:
• It allows the scientists to determine the effect of PKD on the cells’ responses to (various
concentrations of) ouabain.
• It allows the scientists to compare the responses of PKD cells and nor
mal cells (to
ouabain).
Justify the use of a range of ouabain concentrations in the experiment represented in
Figure 1.
1 point
Accept one of the following:
• The scientists need to determine whether different concentrations have different effects
on the
cell numbers.
• The scientists did not know at which concentrat
ion of ouabain there would be an effect.
Total for part (b) 3 points
(c)
Based on the data shown in Figure 2, describe the rel
ationship between the concentration of
ouabain and the
+ +
Na /K ATPase
activity both in normal human kidney (NHK) cells AND
in PKD cells.
1 point
Accept one of the following:
• Increasing concent
rations of ouabain result in decreasing ATPase activity (in both types
of cells).
• There is an inverse relationship/negative correlation between t
he concentration of
ouabain and the ATPase activity (in both types of cells).
The scientists de
termined that
+ +
Na /K ATPase
activity in PKD cells treated with
1 pM
ouabain is 150 units of ATP
hydrolyzed/sec
. Calculate the expected
+ +
Na /K ATPase
activity (units/sec) in PKD cells treated with
10
6
pM
ouabain.
1 point
• 45 (Accept between 40 and 50)
Total for part (c) 2 points
© 2021 College Board
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End of Document
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FAQs of AP® Biology Scoring Guidelines

What types of questions are included in the AP Biology scoring guidelines?
The AP Biology scoring guidelines include various question types such as experimental design, data analysis, and conceptual understanding. Each question is designed to assess students' knowledge of biological principles and their ability to apply scientific reasoning. The guidelines outline how responses are evaluated based on clarity, accuracy, and depth of understanding, ensuring that students know what is expected for high scores.
How can students use the scoring guidelines to prepare for the AP Biology exam?
Students can use the AP Biology scoring guidelines to familiarize themselves with the exam format and the types of questions they will encounter. By reviewing sample responses and understanding the scoring criteria, students can identify areas for improvement in their answers. Practicing with these guidelines helps students develop their ability to articulate scientific concepts clearly and effectively, which is crucial for success on the exam.
What is the significance of the experimental design questions in the AP Biology scoring guidelines?
Experimental design questions in the AP Biology scoring guidelines are significant because they assess students' understanding of the scientific method and their ability to formulate hypotheses, design experiments, and analyze results. These questions require students to demonstrate critical thinking and problem-solving skills, which are essential in biological research. Mastery of these concepts is vital for students aiming to excel in the AP Biology exam and pursue further studies in science.
What biological concepts are emphasized in the AP Biology scoring guidelines?
The AP Biology scoring guidelines emphasize key biological concepts such as cellular processes, genetics, evolution, and ecology. These concepts are foundational to understanding the complexities of life and are integral to the AP curriculum. By focusing on these areas, the guidelines help students connect theoretical knowledge with practical applications, enhancing their overall comprehension of biology.

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