Ap Biology 2013 Exam Review Answers

The AP Biology 2013 exam challenged students on a wide range of biological concepts, from molecular biology and genetics to evolution and ecology. Understanding the exam's structure, key topics, and the types of questions asked is crucial for effective preparation and achieving a high score. This review offers a comprehensive overview of the AP Biology 2013 exam, providing insights into the content, structure, and strategies for success, along with detailed explanations of sample questions that reflect the format and difficulty level of the actual exam.

Understanding the AP Biology Exam Format

The AP Biology exam is designed to assess students' understanding of the core principles of biology and their ability to apply these principles to solve problems. The exam consists of two sections:

• Section I: Multiple Choice: This section comprises 69 multiple-choice questions (60 scored and 9 unscored) that test a student's knowledge of fundamental biological concepts, scientific reasoning, and experimental design. Students have 90 minutes to complete this section.

• Section II: Free Response: This section consists of 2 long free-response questions and 6 short free-response questions that require students to demonstrate their ability to synthesize information, interpret data, and explain biological concepts in a clear and concise manner. Students have 90 minutes (10 minutes for reading and 80 minutes for writing) to complete this section.

Key Topics Covered in the AP Biology Exam

The AP Biology curriculum is organized into four big ideas:

1. Big Idea 1: Evolution: The process of evolution drives the diversity and unity of life. This includes topics such as natural selection, adaptation, speciation, and the history of life on Earth.

2. Big Idea 2: Energetics: Biological systems utilize free energy and molecular building blocks to grow, reproduce, and maintain dynamic homeostasis. This covers concepts such as photosynthesis, cellular respiration, metabolism, and energy transfer within ecosystems.

3. Big Idea 3: Information Storage and Transmission: Living systems store, retrieve, transmit, and respond to information essential for life processes. This encompasses genetics, DNA replication, transcription, translation, cell communication, and the immune system.

4. Big Idea 4: Systems Interactions: Biological systems interact, and these systems and their interactions possess complex properties. This includes ecology, interactions between organisms, population dynamics, and the flow of energy and matter within ecosystems.

Sample Multiple Choice Questions and Answers

To illustrate the types of multiple-choice questions encountered on the AP Biology exam, let's examine a few examples along with detailed explanations:

Question 1:

Which of the following is the most likely explanation for the observation that Antarctic fish have evolved antifreeze proteins?

(A) The fish needed to maintain homeostasis in extremely cold conditions.

(B) The fish wanted to adapt to the new environment.

(C) The fish were trying to avoid competition with other fish species.

(D) The fish's DNA mutated to produce these proteins randomly.

Answer and Explanation:

The correct answer is (A) The fish needed to maintain homeostasis in extremely cold conditions. Antifreeze proteins are an adaptation that helps the fish survive in freezing temperatures by preventing ice crystals from forming in their tissues. Option B is incorrect because evolution is not driven by "wanting" to adapt. Option C might be a secondary factor, but the primary driver is survival in the cold. Option D is partially correct in that mutations play a role in evolution, but it doesn't explain the why behind the adaptation.

Question 2:

Which of the following processes is directly responsible for the production of ATP during cellular respiration?

(A) Glycolysis

(B) Krebs cycle

(C) Electron transport chain and chemiosmosis

(D) Fermentation

Answer and Explanation:

The correct answer is (C) Electron transport chain and chemiosmosis. While glycolysis and the Krebs cycle produce some ATP, the majority of ATP is generated during the electron transport chain and chemiosmosis. This process uses the energy from electrons to pump protons across a membrane, creating a gradient that drives ATP synthase. Fermentation is an anaerobic process that produces a small amount of ATP but is not the primary ATP-generating process in cellular respiration.

Question 3:

A researcher is studying a population of butterflies and observes that the frequency of a particular allele changes over time. Which of the following mechanisms is LEAST likely to be responsible for this change?

(A) Natural selection

(B) Genetic drift

(C) Gene flow

(D) Random mating

Answer and Explanation:

The correct answer is (D) Random mating. Natural selection, genetic drift, and gene flow are all mechanisms that can alter allele frequencies in a population. Natural selection favors individuals with advantageous traits, genetic drift is a random change in allele frequencies due to chance events, and gene flow is the movement of genes between populations. Random mating, however, does not inherently change allele frequencies; it only shuffles existing alleles into different combinations.

Sample Free Response Questions and Answers

The free-response section requires students to demonstrate their understanding of biological concepts through written explanations, data analysis, and experimental design. Let's look at a couple of examples.

Question 1 (Long Free-Response):

A population of frogs lives in a pond. The frogs vary in color, with some being green and others being brown. A drought occurs, and the pond dries up, leaving only a small puddle. As a result, many frogs die, and the surviving frogs are mostly brown.

(a) Explain how the drought could have led to a change in the frequency of green and brown frogs in the population.

(b) Describe the most likely mechanism of evolution that is occurring in the frog population.

(c) If the drought continues for several years, predict how the frog population might further evolve.

Answer and Explanation:

(a) The drought acts as a selective pressure, favoring brown frogs over green frogs. If the brown frogs are better camouflaged in the muddy environment of the shrinking puddle, they are more likely to survive and reproduce. This is an example of natural selection. The frequency of brown frogs will increase in the population because they have a higher survival rate.

(b) The most likely mechanism of evolution is natural selection. The environmental change (drought) favors individuals with a specific trait (brown coloration) that increases their survival and reproductive success. This leads to a shift in the genetic makeup of the population.

(c) If the drought continues, the frog population might continue to evolve towards a higher proportion of brown frogs. Over time, additional adaptations related to drought tolerance might also arise. For example, frogs might evolve to be smaller in size, requiring less water, or they might develop the ability to burrow into the mud to avoid dehydration. If the puddle eventually dries up completely, the frog population might go extinct, or they might migrate to a new location with a more sustainable water source.

Question 2 (Short Free-Response):

Describe the process of translation in protein synthesis. Include the roles of mRNA, tRNA, and ribosomes.

Answer and Explanation:

Translation is the process of synthesizing a polypeptide chain using the information encoded in messenger RNA (mRNA). The process occurs on ribosomes, which are complex structures made of ribosomal RNA (rRNA) and proteins. Transfer RNA (tRNA) molecules play a crucial role in bringing the correct amino acids to the ribosome based on the mRNA sequence.

The mRNA molecule carries the genetic code from the DNA in the nucleus to the ribosome in the cytoplasm. The ribosome binds to the mRNA and moves along it, reading the codons (three-nucleotide sequences) one at a time. Each codon specifies a particular amino acid.

tRNA molecules have an anticodon that is complementary to a specific mRNA codon. Each tRNA is also attached to a specific amino acid. As the ribosome moves along the mRNA, tRNA molecules with the correct anticodon bind to the mRNA codons. The ribosome then catalyzes the formation of a peptide bond between the amino acids, adding them to the growing polypeptide chain.

This process continues until the ribosome reaches a stop codon on the mRNA. At this point, the polypeptide chain is released from the ribosome, and it folds into its functional three-dimensional shape.

Strategies for Success on the AP Biology Exam

To maximize your chances of success on the AP Biology exam, consider the following strategies:

1. Master the Core Concepts: Ensure a solid understanding of the four big ideas and their related concepts. Review your textbook, class notes, and any supplemental materials provided by your teacher.

2. Practice Regularly: Solve as many practice questions as possible, including multiple-choice and free-response questions. This will help you familiarize yourself with the exam format and identify areas where you need to improve.

3. Understand Experimental Design: The AP Biology exam emphasizes experimental design and data analysis. Be prepared to design experiments, interpret data tables and graphs, and identify potential sources of error.

4. Develop Strong Writing Skills: The free-response section requires clear and concise writing. Practice writing well-organized essays that demonstrate your understanding of biological concepts and your ability to apply them to real-world scenarios.

5. Manage Your Time Effectively: Time management is crucial on the AP Biology exam. Practice pacing yourself so that you can complete all the questions within the allotted time. Don't spend too much time on any one question; if you're stuck, move on and come back to it later.

6. Review Past Exams: Studying past AP Biology exams can provide valuable insights into the types of questions asked and the level of difficulty. While the 2013 exam may not be the most recent, it still provides a good representation of the exam's overall format and content.

Tips for Answering Multiple Choice Questions

• Read each question carefully and identify the key information.
• Eliminate obviously wrong answers.
• If you're unsure of the answer, make an educated guess.
• Don't spend too much time on any one question.

Tips for Answering Free Response Questions

• Read each question carefully and understand what is being asked.
• Plan your answer before you start writing.
• Write clearly and concisely.
• Use appropriate biological terminology.
• Support your answers with evidence from your knowledge of biology.
• Address all parts of the question.

Common Mistakes to Avoid

• Lack of Understanding of Core Concepts: A superficial understanding of biological concepts can lead to incorrect answers on both multiple-choice and free-response questions.

• Poor Time Management: Failing to manage your time effectively can result in incomplete answers or rushed work.

• Misinterpreting Questions: Carefully read each question to ensure you understand what is being asked.

• Lack of Clarity in Writing: Unclear and disorganized writing can make it difficult for the graders to understand your answers.

• Neglecting to Practice: Insufficient practice can lead to anxiety and poor performance on the exam.

Utilizing the 2013 Exam for Effective Preparation

While the AP Biology exam is updated periodically to reflect changes in the curriculum and scientific advancements, the 2013 exam remains a valuable resource for preparation. By studying the 2013 exam, students can gain insights into:

• Question Types: The types of multiple-choice and free-response questions that are commonly asked.

• Content Coverage: The specific biological concepts that are emphasized on the exam.

• Difficulty Level: The level of difficulty of the questions.

• Scoring Guidelines: The criteria used to evaluate free-response answers.

By analyzing the 2013 exam, students can identify their strengths and weaknesses and focus their study efforts accordingly. They can also use the exam to practice their time management skills and develop effective strategies for answering different types of questions.

Staying Updated with Current AP Biology Guidelines

While older exams like the 2013 version provide valuable practice, it's essential to supplement your preparation with the most current AP Biology guidelines and resources. The College Board regularly updates the AP Biology curriculum and exam format, so staying informed about these changes is crucial for success. You can access the latest information on the College Board's website, including:

• Course and Exam Description: This document outlines the content, skills, and assessment structure of the AP Biology course.

• Practice Exams: The College Board releases official practice exams that reflect the current exam format and content.

• Scoring Guidelines: These guidelines provide detailed information about how the free-response questions are scored.

By using these resources, you can ensure that you are well-prepared for the AP Biology exam and that you have the knowledge and skills necessary to achieve a high score.

Conclusion

The AP Biology exam is a challenging but rewarding assessment of your understanding of fundamental biological principles. By mastering the core concepts, practicing regularly, developing strong writing skills, and managing your time effectively, you can increase your chances of success. Utilizing resources like the 2013 exam (while being mindful of curriculum updates) can provide valuable insights into the exam format, content, and difficulty level. Remember to stay updated with the latest AP Biology guidelines from the College Board and to approach the exam with confidence and a well-prepared mindset. Good luck!