AP® Biology Practice Test and Practice Questions
Access Includes
- 400+ Exam-style Practice Questions
- Customizable Quiz Generator
- Realistic Timed Test Simulation
- Colorful Visual Explanations
- Step-by-Step Solutions
- Adjustable Smart Study Planner
- Progress Dashboard
- Smart Flashcards
Try These AP Biology Practice Questions
Question
During RNA synthesis in a cell, a cytosine nucleotide is added to a growing RNA strand ending in a guanine-adenine dinucleotide. Which of the following correctly illustrates the structure and orientation of each nucleotide as the reaction takes place?
A.  |
|
B.  |
|
C.  |
|
D.  |
Explanation
Nucleotides are biological molecules composed of the following:
- One pentose sugar (ie, ribose in RNA or deoxyribose in DNA)
- One to three phosphates
- One of the five nitrogenous bases: adenine, cytosine, guanine, thymine (DNA only), or uracil (RNA only)
The nitrogenous base is attached to carbon 1 of the sugar, all phosphates present are attached to carbon 5 (ie, the 5′ end), and a hydroxyl group (OH) is attached to carbon 3 (ie, the 3′ end).
Nucleotides can combine to form long chains (ie, polymers) known as polynucleotides or nucleic acids (ie, RNA or DNA). In biological systems, this occurs when the 5′ triphosphate (three connected phosphates) on a free nucleotide reacts with the 3′ hydroxyl group of the growing nucleic acid.
In the given RNA synthesis reaction, cytosine (a free nucleotide) is added to a guanine-adenine dinucleotide on the growing nucleic acid. Because cytosine is the free nucleotide in this scenario, it must contain a 5′ triphosphate, which must align with the 3′ hydroxyl group of guanine-adenine for the addition to occur. The diagram shown in Choice C correctly depicts this structure and orientation.
The diagrams shown in Choice A, Choice B, and Choice D show incorrect structures and/or orientations for the nucleotides.
Things to remember:
Nucleotides consist of a pentose sugar linked to a nitrogenous base (ie, adenine, cytosine, guanine, thymine [DNA only], uracil [RNA only]) at carbon 1, one or more phosphates linked to the 5′ end, and a hydroxyl group linked to the 3′ end. Nucleic acids grow when the 5′ triphosphate of a free nucleotide reacts with the 3′ hydroxyl group of the growing nucleic acid chain.
Question
Cellular organelles are centrifuged in a test tube filled with a liquid that becomes denser with increasing depth. Different organelles come to rest at depths that match their density, as shown in the figure below. Each organelle remains functional during and after centrifugation.
The purpose of the experiment is to determine which enzymes are found in each organelle by measuring enzyme activities at different densities. Given that steroid 8-isomerase is an enzyme involved in cholesterol synthesis, which of the following best represents the amount of steroid 8-isomerase activity as a function of density in the test tube?
A.
|
|
B.
|
|
C.
|
|
D.
|
Explanation
Eukaryotic cells contain several membrane-bound compartments called organelles, each of which is specialized to carry out specific functions. For example, the nucleus carries out DNA and RNA synthesis, lysosomes degrade large biomolecules, and mitochondria are responsible for many metabolic reactions.
The endoplasmic reticulum (ER) is a network of membrane-bound compartments that help facilitate multiple cellular processes including protein and lipid synthesis. The ER is broadly divided into two components: the rough ER and the smooth ER. Most lipids, including cholesterol, are synthesized in the smooth endoplasmic reticulum (SER). Therefore, the enzymes responsible for cholesterol synthesis are most likely found in the SER.
The question states that steroid 8-isomerase is involved in cholesterol synthesis, indicating that it is most likely found in the SER. The figure shows that after centrifugation, the endoplasmic reticulum (including the SER) is found at a density of approximately 1.14 g/cm3. Therefore, the correct graph should show high steroid 8-isomerase activity at 1.14 g/cm3 and low activity elsewhere (Choice C).
(Choices A, B, and D) These graphs show steroid 8-isomerase activity in the nucleus, lysosomes, and mitochondria, respectively. These organelles are not involved in cholesterol synthesis, so steroid 8-isomerase is unlikely to be found at the densities that correspond to these organelles.
Things to remember:
Lipid synthesis occurs primarily in the smooth endoplasmic reticulum, where the enzymes that catalyze the necessary reactions are found.
Question
The combined expression of several genes has been shown to influence the production of unique fingerprint patterns in each human being. These fingerprint patterns are fully formed approximately two months before birth. Which of the following would confirm that fingerprint pattern is an example of a trait exhibiting phenotypic plasticity?
| A. Fingerprint patterns always differ when comparing two individuals that are not related. | |
| B. Identical twins sharing all their DNA sequences still express different fingerprint patterns. | |
| C. If the genes responsible for coding fingerprint patterns are inhibited, fingerprint patterns will not form before birth. | |
| D. Each gene that codes for fingerprint patterns is transcribed at a different time point during embryonic development. |
Explanation
Gene expression and the resulting phenotypes in organisms may be affected by several factors, such as:
- The allele type inherited for a gene (eg, dominant or recessive)
- The presence of regulatory molecules (eg, transcription factors)
- Environmental factors (eg, temperature)
Phenotypic plasticity occurs when environmental differences cause individuals of the same species with similar or identical genotypes to express different phenotypes.
This question describes fingerprint pattern development in humans due to expression of several genes. If identical twins (ie, individuals who share 100% of their DNA sequences) still express different fingerprint patterns, this would confirm that this trait exhibits phenotypic plasticity. Accordingly, environmental differences experienced by each twin during development (eg, differences in position or access to nutrients within the mother) may alter fingerprint pattern, regardless of their genotype.
The remaining answer choices do not provide evidence that environmental differences in genetically similar individuals affect expression of unique fingerprint patterns.
(Choice A) Fingerprint patterns are unique in each person (regardless of family relationship), but this alone does not suggest that the trait exhibits phenotypic plasticity.
(Choice C) Inhibition of genes encoding fingerprint patterns only prevents formation of these patterns during development.
(Choice D) There is no information given to suggest that genes involved in the development of fingerprint patterns are transcribed at different time points during development.
Things to remember:
Gene expression may be affected by environmental influences, leading to phenotypic plasticity (same species individuals with similar/identical genotypes that express different phenotypes).
Question
Bats are flying mammals that can locate quiet flying prey (eg, moths) in the dark by producing sound waves at certain frequencies that reflect off the prey back to the bat. Bats' ears are specialized to detect the reflected sound frequencies.
Some species of tiger moths (genus Cisthene) carry toxins from plants they feed on. These toxins make the tiger moths distasteful to bats. Bats learn to avoid eating such toxin-carrying moths because the tiger moths produce sounds at specific frequencies that the bats can detect. Other moth species (genus Yponomeuta) produce sounds at the same frequency as those produced by tiger moths.
Which of the following claims is most consistent with this information?
| A. Yponomeuta moths that produce less sound are less likely to be eaten by bats. | |
| B. Bats cannot detect sounds at the frequency produced by Yponomeuta moths. | |
| C. Yponomeuta moths that sound like tiger moths to bats produce more surviving offspring. | |
| D.Tiger moths and Yponomeuta moths obtain the same toxins by eating the same plants. |
Explanation
Signaling behaviors can affect organisms from the same or different species and increase organisms' reproductive success (ie, evolutionary fitness) in various ways (eg, improving self-defense, increasing the ability to obtain food and find mates).
According to the question, certain toxin-carrying tiger moths are distasteful to bats and produce sounds at frequencies detected by bats. Therefore, bats learn to avoid eating these tiger moths.
However, some moths of the genus Yponomeuta produce sounds at the same frequency as the tiger moths that are distasteful to bats. Because bats tend to avoid eating the distasteful tiger moths, bats would also avoid eating Yponomeuta moths that produce the same frequencies, making it more likely that such moths would survive to reproduce.
Therefore, a claim that is consistent with the presented information is that Yponomeuta moths that sound like tiger moths to bats produce more surviving offspring.
(Choice A) Yponomeuta moths that produce less sound are more likely (not less likely) to be eaten by bats. The bats would not receive as strong a signal to avoid Yponomeuta moths, and the bats can still target these moths using reflected sound.
(Choice B) Tiger moths produce sound frequencies that bats can hear, and Yponomeuta moths produce sounds at the same frequencies; therefore, bats can detect sounds at the frequency produced by Yponomeuta moths.
(Choice D) No information is given in the question indicating that tiger moths and Yponomeuta moths eat the same plants.
Things to remember:
Organisms produce signals that affect the behavior of other organisms. Signal production can benefit organisms in various ways that increase their reproductive success.
Make the AP Biology Exam Feel Like Practice
Our AP Biology practice test questions are just like the exam and make you think critically. They’ll help you spot trick answers and boost your confidence for test day!
Create Custom Quizzes
Simulate Exam Conditions
Boost Your Study Methods
Score Higher with Quality Content and Learning Tools
Exceptional Content
Understand the “why” with our simplified breakdowns of how to approach each practice question and topic. Our clear question explanations and vivid visuals help you spot and avoid trick answers so you’ll ace the AP Biology exam. Our exclusive technique, backed by active learning principles, maximizes learning and retention.
Digital Flashcards & Notebook
Smart flashcards boost your memory with spaced repetition, and the My Notebook feature helps you take notes to grasp key concepts better and review important AP Biology topics. With the click of a button, easily transfer content from our AP Bio question explanations to your flashcard or notebook for the best learning experience.
Performance Tracking
Turn your challenges into strengths by targeting specific AP Biology topics and skills. Our advanced analytics dashboard tracks your progress across AP Bio practice tests and practice questions, showing you exactly where you need improvement. By monitoring your results, you can save study time, focus on weak areas, and build the confidence needed for test day.
Access Anywhere, Anytime
Our digital-first test prep lets you study anywhere — at home or on the go. Get instant feedback with research-based answer explanations for each question. Once you’ve mastered the concepts, use the timer to build your speed and confidence under pressure.
Choose How You Study and Save
Choose How You Study and Save
AP Biology Question Bank
Starting at $39
400+ Exam-Level Questions
Generate Custom Practice Tests
Progress Tracking Dashboard
Choose Your Topics
Smart Study Planner
400+ Exam-Level Questions
Generate Custom Practice Tests
Progress Tracking Dashboard
Choose Your Topics
Print and Digital Study Guide
120+ Check-for-Understanding Questions
Smart Study Planner
Expert-led Video Lessons
Hear From Our AP Students
UWorlds multiple choice questions are similar to the ones on the official AP exam and allowed me to time myself for each question. This was very helpful for me as I was able to answer questions faster and could finish the questions on the actual exam. The explanations for each question went in-depth and gave important details pertaining to events in the timeline. Through this, I was able to gain important skills for the exam and get a 5.
Before, I had a hard time studying and staying focused because it was just boring, but now with UWorld, not only can I focus, but I actually feel motivated to learn!
The explanations were clear and I could practice the question based on units. I got a 5 in the end!! So, I think it’s very helpful and I’ll be using it to study for my future exams 🙂 You guys provide so many different functions to help students like me, and I really appreciate it, it’s really worth the money.
Frequently Asked Questions (FAQs)
Who writes UWorld AP Biology practice questions and explanations?
How often is the UWorld AP Biology question bank updated?
We regularly update our AP Biology question bank (QBank) to give you the most up-to-date practice content for the AP Biology exam.
Do UWorld AP Biology practice tests reflect the actual exam?
Will UWorld’s AP Biology practice questions cover everything I need for a top score?
How many AP Biology practice tests are available with UWorld?
Can I retake AP Biology practice tests with UWorld?
Yes. Our AP Biology practice test generator (QBank) allows you to add questions you’ve skipped, answered incorrectly, or simply want to review again from previous practice sessions.
How long should I spend on each AP Biology practice test question to simulate the real exam experience?
To simulate the real exam experience, set your AP Biology practice test to include 60 questions and limit yourself to 90 minutes.
How does UWorld’s AP Biology question bank help students succeed?
How is UWorld different from other AP Biology question banks?
Our AP Biology practice questions mirror the official AP Biology exam questions. Detailed answer explanations are comprehensively illustrated and help you learn from incorrect choices, clarify misconceptions, and understand how to approach questions rather than just answer them.