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AP Computer Science Principles

AP Computer Science Principles Practice Test: Practice Test 10

Practice Test 10 for AP Computer Science Principles: real questions and explanations from the Varsity Tutors practice-test pool.

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Question 1 of 25

An Online Retail System uses data abstraction to recommend products. Raw logs record each click and purchase: (customerID, itemID, time, price, ratingText). The system simplifies this into an abstract customer profile with categories: preferredCategories, averageSpend, and recentPurchases. It also computes purchase patterns, such as “often buys running shoes after viewing fitness trackers.” A recommendation algorithm then compares a shopper’s profile to patterns and selects items. Example pseudocode:

IF profile.preferredCategories contains "Fitness" AND profile.averageSpend > 50:
   recommend(topItems["Fitness"])

Based on the scenario described, identify the process that uses abstraction to convert raw data into actionable insights.

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Question 1

An Online Retail System uses data abstraction to recommend products. Raw logs record each click and purchase: (customerID, itemID, time, price, ratingText). The system simplifies this into an abstract customer profile with categories: preferredCategories, averageSpend, and recentPurchases. It also computes purchase patterns, such as “often buys running shoes after viewing fitness trackers.” A recommendation algorithm then compares a shopper’s profile to patterns and selects items. Example pseudocode:

IF profile.preferredCategories contains "Fitness" AND profile.averageSpend > 50:
   recommend(topItems["Fitness"])

Based on the scenario described, identify the process that uses abstraction to convert raw data into actionable insights.

  1. Replacing click logs with profiles and patterns that the recommender can compare. (correct answer)
  2. Deleting most purchase records to ensure the algorithm runs without any bias.
  3. Encrypting customer histories so recommendations are generated from hidden data only.
  4. Adding extra tracking fields so the algorithm must process more complex records.

Explanation: This question tests AP Computer Science Principles: understanding data abstraction and its application in algorithmic processing. Data abstraction involves simplifying complex data systems by classifying and organizing data into manageable categories, allowing for efficient processing and manipulation by algorithms. In the scenario, raw click and purchase logs are abstracted into customer profiles (preferredCategories, averageSpend, recentPurchases) and purchase patterns to facilitate product recommendations. Choice A is correct because it accurately identifies how abstraction replaces detailed logs with profiles and patterns that the recommendation algorithm can efficiently compare. Choice D is incorrect because it misinterprets abstraction as adding complexity through extra fields, a common misconception when students confuse data enrichment with abstraction. To help students: Emphasize that abstraction creates simplified representations that capture essential patterns. Practice identifying how raw transaction data transforms into actionable profiles and patterns.

Question 2

A city’s emergency alert system sent short messages from a central office to many radio towers. Because messages traveled through noisy links, a few packets occasionally arrived with altered bits. Each packet included extra information that let the receiver notice a mismatch. When a mismatch appeared, the receiver corrected small errors when possible; otherwise it requested the packet again. This helped ensure that evacuation notices were not changed into confusing text. During a thunderstorm, the system still delivered accurate alerts to most towers. In the example given, which mechanism ensures system operation when a component fails?

  1. Error detection and correction keeps data accurate (correct answer)
  2. Load balancing spreads users across servers
  3. A faster antenna prevents all interference
  4. Turning off the network avoids wrong messages

Explanation: This question tests AP Computer Science Principles skills, specifically understanding fault tolerance in computing systems and networks. Fault tolerance is the ability of a system to continue operating properly in the event of a failure of some of its components. It involves mechanisms like redundancy, error detection and correction, and failover. In the passage, the emergency alert system uses error detection and correction to identify and fix corrupted bits in messages, ensuring accurate delivery of critical information. Choice A is correct because it accurately identifies error detection and correction as the mechanism that keeps data accurate despite noisy transmission links. Choice C is incorrect because it suggests preventing interference entirely, which is impossible in real-world conditions as shown by the thunderstorm scenario. To help students, emphasize that error detection and correction handles data corruption, not component failures. Watch for: confusion between different fault tolerance mechanisms and unrealistic expectations about preventing all errors.

Question 3

A home security company monitored sensors over a wireless network. Sometimes interference flipped bits in a message, so the system added a small check value to each packet. If the check did not match, the receiver requested the packet again, and the correct alert was delivered. This kept door and window events accurate even on noisy nights. In the example given, how does the described system maintain functionality during a failure?

  1. It encrypted data to hide sensor names
  2. It detected errors and requested resend (correct answer)
  3. It boosted volume so alerts sounded louder
  4. It deleted packets to prevent delays

Explanation: This question tests AP Computer Science Principles skills, specifically understanding fault tolerance in computing systems and networks. Fault tolerance is the ability of a system to continue operating properly in the event of a failure of some of its components. It involves mechanisms like redundancy, error detection and correction, and failover. In the passage, the system uses error detection and correction by adding check values to packets and requesting retransmission when errors are detected. Choice B is correct because it accurately describes how the system detects errors through check values and requests resending of corrupted packets. Choice A is incorrect because encryption is about security and privacy, not error detection - the passage specifically mentions detecting bit flips from interference. To help students, emphasize the difference between error detection (finding mistakes) and other fault tolerance mechanisms. Practice identifying checksum/parity concepts and how they enable reliable communication over unreliable channels.

Question 4

Refer to the text: In genome sequencing, distributed computing stores reads across networked nodes and uses message passing; if one node fails, other nodes continue and data can be re-copied. How does distributed computing enhance fault tolerance?

  1. By keeping computation on one machine so failures cannot spread across a network.
  2. By requiring constant shared-memory access, preventing any single component from failing.
  3. By replicating data and rerouting tasks so other nodes continue when one node fails. (correct answer)
  4. By guaranteeing perfect accuracy in every alignment, eliminating the impact of hardware faults.

Explanation: This question tests understanding of parallel and distributed computing concepts, specifically how distributed computing provides fault tolerance in genome sequencing applications. Distributed computing involves multiple independent systems connected via network that can continue operating even when individual nodes fail, unlike parallel computing which typically operates within a single system. In this passage, distributed computing is illustrated through genome sequencing that stores reads across networked nodes using message passing, with the ability to re-copy data and continue when nodes fail. Choice C is correct because it accurately describes how distributed computing enhances fault tolerance by replicating data and rerouting tasks so other nodes can continue when one node fails, which is the fundamental mechanism of fault tolerance in distributed systems. Choice B is incorrect because it describes shared-memory access, which is characteristic of parallel computing within a single system, not distributed computing across networked nodes. To help students: Emphasize that fault tolerance in distributed systems comes from redundancy and independence of nodes. Use real-world examples like cloud storage services that continue working even when servers fail. Watch for: confusion between parallel computing's shared memory and distributed computing's message passing architectures.

Question 5

Not every effect of a computing innovation is anticipated in advance by its designers. Which of the following provides the best example of an unintended effect?

  1. The developers of the World Wide Web, intending it for scientific data sharing, did not foresee its use for global e-commerce. (correct answer)
  2. The developers of a word processing program included a spell-check feature to help users avoid typing errors.
  3. The developers of a banking app included encryption to protect users' financial information from being stolen.
  4. The developers of a mapping application provided turn-by-turn navigation to help users find their destinations.

Explanation: The correct answer is A. The transformation of the Web from a scientific network to a commercial hub was a massive, unforeseen development, making it a prime example of an unintended effect. Choices B, C, and D all describe features that were clearly intended and designed for a specific, anticipated purpose.

Question 6

Which of the following statements best describes a significant trade-off of using lossy compression?

  1. In exchange for a smaller file size, some amount of the original data is permanently discarded. (correct answer)
  2. The process is always reversible, but it requires special software to decompress the file to its original state.
  3. It can only be applied to text data, making it unsuitable for multimedia files like images and videos.
  4. It typically results in a larger file than the original, but the data can be transmitted much more quickly.

Explanation: The core trade-off of lossy compression is quality for size. To achieve a smaller file size than what is typically possible with lossless methods, some of the original information is permanently removed. This trade-off is often acceptable for media files where the loss is not easily perceived.

Question 7

A tech company develops a new application and wants to gather user feedback. They collect data by sending a survey link exclusively to a list of technology bloggers and journalists who have previously written about similar apps.

Which of the following is the most likely source of bias in the collected data?

  1. The data collection method over-represents individuals who are technology experts, whose opinions may not reflect the general user population. (correct answer)
  2. The survey questions might be excessively long, leading to incomplete data from some of the respondents who start but do not finish.
  3. The company is collecting too much data from each respondent, which will make it difficult to process and analyze the results effectively.
  4. The data are collected anonymously, which prevents the company from asking follow-up questions to the respondents to clarify their answers.

Explanation: The correct answer is A. The data is being collected from a specific, non-representative group (tech bloggers and journalists). This method introduces sampling bias because this group's experience, expectations, and technical skills may differ significantly from those of an average user, leading to skewed feedback.

Question 8

Which of the following is guaranteed when using a lossless data compression algorithm?

  1. The compressed file will always be at least 50 percent smaller than the original file.
  2. The time required to compress the file will be less than the time required to decompress it.
  3. The compressed file can be used by applications without needing to be decompressed first.
  4. The original data can be restored in its entirety from the compressed data without any loss. (correct answer)

Explanation: The defining feature and guarantee of any lossless compression algorithm is perfect fidelity. The decompression process is able to reconstruct the original data stream perfectly, bit for bit, from the compressed version.

Question 9

A Monte Carlo program estimates how often a savings goal is reached by randomly sampling monthly income changes and expenses. Randomness is needed because real spending and earnings vary and cannot be predicted exactly. One run may reach the goal early, while another falls short due to higher sampled expenses. Based on the scenario above, how do random values affect the outcome of this simulation?

  1. They create many possible financial paths, showing how outcomes vary under different sampled conditions. (correct answer)
  2. They make the final result predictable, so the same goal outcome appears every time.
  3. They are essential for all programs, so this simulation would not run without randomness.
  4. They mainly reduce battery usage, which is the key purpose of Monte Carlo simulations.

Explanation: This question tests understanding of the use of random values in algorithms, specifically in AP Computer Science Principles. Random values are used in algorithms to introduce variability and simulate real-world uncertainty, crucial in applications like simulations and security. In the given scenario, random values are used to sample monthly income changes and expenses in a Monte Carlo simulation, affecting savings goal predictions. Choice A is correct because it accurately reflects how random values create multiple financial scenarios showing outcome variability, demonstrating an understanding of Monte Carlo methods for financial modeling. Choice B is incorrect because it suggests randomness makes results predictable, which contradicts the fundamental purpose of Monte Carlo simulations - students often confuse multiple trials with identical outcomes. To help students: Emphasize that Monte Carlo simulations use randomness to model uncertainty in financial planning. Practice running multiple simulations to see how random sampling creates a probability distribution of reaching financial goals.

Question 10

A playlist list of strings starts as ['Intro','Skyline','Drift','Neon','Finale']. You remove 'Neon' because it is unavailable offline before your run. Based on the scenario above, how does the list change after removing the element?

  1. ['Intro','Skyline','Drift','Finale'] (correct answer)
  2. ['Neon','Intro','Skyline','Drift','Finale']
  3. ['Intro','Skyline','Drift','Neon','Finale','Neon']
  4. ['Intro','Skyline','Neon','Drift','Finale']

Explanation: This question tests understanding of list operations in programming, specifically removing elements and how it affects list structure. In programming, the remove() method deletes the first occurrence of a specified value, and all subsequent elements shift left to fill the gap. In this scenario, the playlist ['Intro','Skyline','Drift','Neon','Finale'] has 'Neon' at index 3, which is removed. Choice A is correct because removing 'Neon' results in ['Intro','Skyline','Drift','Finale'], with 'Finale' shifting from index 4 to index 3. Choice D is incorrect because it shows 'Neon' still present but in a different position, reflecting a misunderstanding that remove() might reorder rather than delete elements. To help students: Use animations showing how list elements shift after removal, practice predicting list contents after various operations, and emphasize that remove() completely deletes the element. Have students trace index changes when elements are removed.

Question 11

A passage in Arial examines Intellectual Property and Open Source in a robotics club using code from a public repository. It describes students modifying an open-source motor-control program and combining it with a proprietary sensor module donated by a company. It defines intellectual property as protected code and inventions, and notes open-source licenses can impose conditions on redistribution, while proprietary modules may be protected as trade secrets. Stakeholders include students, the donating company, maintainers, competition organizers, and judges. Scenarios include posting the combined code online, receiving a takedown request, and debating whether to publish only the open-source portion. According to the passage, what are the potential consequences of redistributing code while ignoring license conditions?

  1. Takedown demands and loss of permission to use or share the licensed code (correct answer)
  2. Automatic eligibility for scholarships due to public sharing
  3. A guarantee that proprietary trade secrets become unenforceable worldwide
  4. Mandatory government approval before any code can run on a robot

Explanation: This question tests understanding of legal and ethical concerns in computing, focusing on intellectual property violations in mixed open-source and proprietary code environments. Legal concerns in computing often involve compliance with both open-source licenses and proprietary restrictions, while ethical concerns focus on moral implications such as respecting creators' rights and maintaining trust in the developer community. In this passage, the text discusses combining open-source motor control with proprietary sensor code as a case of complex licensing obligations. Choice A is correct because it accurately reflects the passage's emphasis on potential takedown demands and loss of permission to use the code, as shown by the scenario of receiving a takedown request after posting combined code online. Choice C is incorrect because it confuses the consequences of sharing code with changes to trade secret law, a common error when students misunderstand how intellectual property protections work. To help students, encourage careful consideration of license compatibility and emphasize that mixing code with different licenses requires understanding each set of obligations. Practice identifying potential conflicts between open-source and proprietary licenses and understanding the legal remedies available to rights holders.

Question 12

A remote-learning program is built to provide interactive history lessons for students who cannot attend class in person. Each unit includes short readings, primary-source questions, and activities where students sort claims into “supported” or “unsupported” categories. The program tracks which reasoning skills are strong, which mistakes repeat, and how often students revise their responses after feedback. It uses that information to recommend the next activity, either reinforcing a skill or introducing a new challenge. Teachers and school leaders review dashboards that summarize class trends, helping them plan live discussions that address common gaps. In surveys, students said they preferred clear, calm prompts over harsh error messages, so the team revised the tone and reduced unnecessary interruptions. The program’s purpose is to deliver instruction that adapts to student needs while keeping learners engaged.

According to the text, which feature of the program contributes most to its efficiency?

  1. Its adaptive recommendations use tracked mistakes to focus practice, limiting time spent on already-mastered skills. (correct answer)
  2. Its public leaderboards push students to work faster, even when accuracy and understanding decline.
  3. Its primary tool is a game-style chat room, where students discuss topics without structured lesson activities.
  4. Its main feature is collecting unrelated personal details, which increases storage needs and slows lesson delivery.

Explanation: This question tests understanding of a computer program's function and purpose in creative development contexts (AP CSP). Understanding program function involves recognizing what the program does, while purpose relates to its intended outcome and impact on users. In this passage, the program tracks reasoning skills and repeated mistakes to recommend appropriate next activities, avoiding unnecessary repetition of mastered content. Choice A is correct because it identifies the key efficiency feature: adaptive recommendations that focus practice on areas needing improvement, saving time by not repeating mastered skills. Choice B is incorrect because the passage mentions students preferred clear, calm prompts and the team reduced interruptions, not public leaderboards that push speed over accuracy. To help students: Look for features that optimize the learning process and save time or resources. Practice identifying how adaptive systems improve efficiency through targeted interventions.

Question 13

Binary Basics passage: Binary is a base-2 system using only 0 and 1, while decimal is base-10 using digits 0–9. For instance, decimal 6 is binary 110. Computers use binary states (off/on) as bits, and group bits into bytes to store and process data. According to the text, How does binary differ from the decimal system?

  1. Binary uses digits 0–9 like decimal
  2. Binary is base-2 using only 0 and 1 (correct answer)
  3. Binary is base-10, but written with fewer digits
  4. Binary always writes digits in reverse order

Explanation: This question tests understanding of binary numbers and their application in computing, specifically the fundamental differences between binary and decimal number systems. Binary is a base-2 numeral system that uses only two digits, 0 and 1, to represent all numbers, which is essential for digital computing. The passage clearly states that binary is base-2 using only 0 and 1, while decimal is base-10 using digits 0-9, establishing the key distinction between these systems. Choice B is correct because it accurately identifies binary as a base-2 system using only digits 0 and 1, which directly matches the passage's explanation. Choice A is incorrect because it suggests binary uses the same digits (0-9) as decimal, which contradicts the fundamental definition of binary as using only two digits. To help students: Emphasize the concept of different number bases and how the base determines the available digits. Use comparison charts showing decimal (base-10) versus binary (base-2) to reinforce the limited digit set in binary and practice identifying which digits are valid in each system.

Question 14

A coding contest problem asks for Fibonacci(n) with n≤35n \le 35n≤35 and a 1-second limit. Two solutions are shown:

Pseudocode (Naive Recursion):

procedure fibRecursive(n)
  if n <= 1
    return n
  return fibRecursive(n - 1) + fibRecursive(n - 2)

Time complexity: O(2n)O(2^n)O(2n).

Pseudocode (Dynamic Programming):

procedure fibDP(n)
  if n <= 1
    return n
  prev <- 0
  curr <- 1
  for i <- 2 to n
    next <- prev + curr
    prev <- curr
    curr <- next
  return curr

Time complexity: O(n)O(n)O(n).

What is the primary advantage of using fibDP over fibRecursive?

  1. It reduces repeated work, changing growth from O(2n)O(2^n)O(2n) to O(n)O(n)O(n). (correct answer)
  2. It makes Fibonacci independent of n, so the runtime becomes O(1)O(1)O(1).
  3. It guarantees exact results only for large n, unlike recursion.
  4. It sorts intermediate values, which is why it improves from O(n2)O(n^2)O(n2) to O(n)O(n)O(n).

Explanation: This question tests AP Computer Science Principles on algorithmic efficiency, specifically understanding how dynamic programming eliminates redundant computation. Algorithmic efficiency refers to how effectively an algorithm performs in terms of time and space, often expressed using Big O notation to represent time complexity. In this passage, the comparison shows how naive recursion recalculates the same Fibonacci values multiple times (leading to O(2^n) complexity), while dynamic programming stores and reuses previously calculated values (achieving O(n) complexity). Choice A is correct because it accurately identifies that dynamic programming reduces repeated work, changing growth from exponential O(2^n) to linear O(n) by storing intermediate results instead of recalculating them. This demonstrates understanding of memoization's impact on efficiency. Choice B is incorrect because it claims the runtime becomes O(1) (constant time), which would mean the algorithm takes the same time regardless of n - this is false as the loop still runs n times. This error often occurs when students confuse improved efficiency with constant-time operations. To help students: Draw the recursion tree for fib(5) showing repeated calculations, then show how DP calculates each value only once. Emphasize that O(n) is still dependent on n, just linearly rather than exponentially. Watch for: students who think any optimization makes algorithms constant-time or who don't understand how storing results prevents recalculation.

Question 15

Even if an email appears to be from a known sender, what is the most significant security risk of opening an unexpected file attachment?

  1. The sender's email account could have been compromised, and the attachment may contain malware. (correct answer)
  2. The file could be in a format that the user's computer is unable to open.
  3. The file could use a large amount of Internet bandwidth to download.
  4. The file's contents might violate the sender's company policy on email usage.

Explanation: Email accounts can be compromised and used to send malware to contacts. Therefore, an unexpected attachment, even from a known sender, poses a significant risk of containing a virus or other malicious software.

Question 16

Introduction: A university uses facial recognition to take attendance in large lecture halls. Examples of Bias: Computing bias is a pattern of unfair outcomes produced by a system, often tied to the data it learns from and the choices people make when building it. Some facial recognition systems show higher error rates for women and for students with darker skin tones when those groups are underrepresented in the training images. How Bias Emerges: Bias can come from limited photo collections, poor image quality, and testing that does not reflect the student body. Impacts: Students may be marked absent incorrectly, which can affect grades and increase conflict with instructors. Mitigation Strategies: The university can use multiple attendance options, audit errors by group, and allow quick correction without penalties.

According to the passage, what is a consequence of computing bias as described in the text?

  1. It can cause some students to be marked absent incorrectly (correct answer)
  2. It ensures attendance records are always error-free
  3. It improves lecture audio quality for all students
  4. It affects only students who choose online classes

Explanation: This question tests AP Computer Science Principles skills: understanding computing bias and its societal impact. Computing bias occurs when algorithms or data sets favor certain outcomes, often reflecting societal inequalities. In the passage, the impact of bias in university attendance systems is highlighted, showing how facial recognition can have higher error rates for women and students with darker skin tones. Choice A is correct because it accurately reflects the passage's statement that 'Students may be marked absent incorrectly, which can affect grades and increase conflict with instructors.' Choice B is incorrect because it contradicts the passage's discussion of errors and bias. To help students: Emphasize identifying specific consequences mentioned in the text rather than idealized outcomes. Watch for: Answer choices that promise perfection or error-free performance when the passage discusses bias and errors.

Question 17

What is the decimal value of the 8-bit binary number 10110011?

  1. 179 (correct answer)
  2. 163
  3. 187
  4. 83

Explanation: The binary number 10110011 is calculated by summing the powers of 2 for each position with a '1': 1×27+0×26+1×25+1×24+0×23+0×22+1×21+1×201 \times 2^7 + 0 \times 2^6 + 1 \times 2^5 + 1 \times 2^4 + 0 \times 2^3 + 0 \times 2^2 + 1 \times 2^1 + 1 \times 2^01×27+0×26+1×25+1×24+0×23+0×22+1×21+1×20 = $128+0+32+16+0+0+2+1=179\$128 + 0 + 32 + 16 + 0 + 0 + 2 + 1 = 179$128+0+32+16+0+0+2+1=179.

Question 18

Based on the simulation described, an environmental science class builds a climate change model to explore local sea-wall planning. The real-world problem is estimating future flooding risk without waiting decades for measurements. The simulation advances year by year from 2025 to 2100. CarbonEmissionIndex starts at 100 and changes by emissionReduction (0%–5% per year). TemperatureIncrease (in °C) rises when emissions stay high, and SeaLevelRise (in cm) increases as temperature rises. A simple feedback loop is included: as TemperatureIncrease grows, iceMeltFactor (low/medium/high) increases, which further accelerates SeaLevelRise in later years. The algorithm runs multiple scenarios, compares outputs to historical temperature records for calibration, and then repeats with slightly adjusted sensitivity values until the 1990–2020 trend is closely reproduced. Example: setting emissionReduction to 3% per year slows TemperatureIncrease, which later reduces SeaLevelRise compared with 0% reduction. Which factor is most critical to the simulation's accuracy?

  1. Calibrating sensitivity so the model reproduces the historical 1990–2020 temperature trend. (correct answer)
  2. Assuming SeaLevelRise decreases whenever TemperatureIncrease increases, to balance the model.
  3. Using a single fixed iceMeltFactor that never changes with temperature, for simplicity.
  4. Choosing any emissionReduction value, because outcomes stay nearly identical across scenarios.

Explanation: This question tests AP Computer Science Principles skills, specifically understanding and analyzing simulations. Simulations use algorithms to model real-world processes, allowing variable manipulation to predict outcomes. They iterate through scenarios, refining results to improve accuracy. In this scenario, the simulation models climate change impacts from 2025 to 2100, with variables like emissionReduction (0%-5% per year) and iceMeltFactor (low/medium/high) affecting temperature increase and sea level rise through feedback loops. Choice A is correct because calibrating sensitivity to reproduce the historical 1990-2020 temperature trend ensures the model's parameters are grounded in reality before making future projections - this validation step is critical for simulation accuracy. Choice C is incorrect because it misunderstands the feedback mechanism - the passage explicitly states that iceMeltFactor increases as temperature rises, not that it remains fixed, which is essential for modeling accelerating effects. To help students, emphasize the importance of model validation against historical data before using simulations for predictions. Practice by having students identify which parameters need calibration and understand how feedback loops create non-linear effects in complex systems.

Question 19

The widespread use of file-sharing software for downloading and distributing copyrighted movies and music without payment or permission raises significant legal and ethical concerns. This practice directly challenges the value and ownership of what?

  1. Digital certificates
  2. Network protocols
  3. Intellectual property (correct answer)
  4. Public key encryption

Explanation: Movies and music are forms of intellectual property, protected by copyright. Unauthorized file-sharing undermines the legal framework that allows creators to control and be compensated for their work, thus challenging the value and ownership of that property. Digital certificates (A), network protocols (B), and public key encryption (D) are technologies related to security and communication, not the legal status of the content being shared.

Question 20

A user repeatedly edits and saves a digital photo using a JPEG format, which is a lossy compression scheme. What is the most likely outcome for the image after many cycles of editing and saving?

  1. The image quality will progressively degrade because each save operation discards more data. (correct answer)
  2. The file size of the image will increase with each save, eventually becoming larger than the original.
  3. The image quality will remain identical to the original, as the compression is reapplied to the already compressed data.
  4. The image will automatically convert to a lossless format to prevent further quality degradation.

Explanation: This phenomenon is known as generation loss. Each time an image is saved in a lossy format, the compression algorithm is applied again, and more data is discarded. This loss is cumulative, leading to a noticeable degradation of quality after several save cycles.

Question 21

A user installs a software utility from the Internet. Weeks later, they discover that their online banking credentials have been stolen. A security expert determines that the utility included a hidden program that captured all of the user's keyboard inputs. This method of attack is known as which of the following?

  1. Keylogging (correct answer)
  2. Phishing
  3. Encryption
  4. Authentication

Explanation: Keylogging is the use of a program to record every keystroke made by a computer user. This information can then be used to steal passwords and other confidential data. Phishing involves tricking a user, while encryption and authentication are security measures.

Question 22

When a user accesses a website, their browser uses the Hypertext Transfer Protocol (HTTP). What is the primary role of HTTP in this context?

  1. It is a protocol used by the World Wide Web to request and deliver web pages and other resources. (correct answer)
  2. It is a protocol that assigns a unique, permanent address to the user's computer on the Internet.
  3. It is a protocol that encrypts all network traffic to ensure privacy and security for the user.
  4. It is a protocol that manages the physical transmission of data over network cables or wireless signals.

Explanation: HTTP is the application-layer protocol that forms the foundation of data communication for the World Wide Web. Web browsers act as HTTP clients, and web servers act as HTTP servers, exchanging requests and responses to deliver web content. (CSN-1.D.2)

Question 23

A streaming video service uses a program to recommend new shows to a user. The program's recommendations are based on the user's previously watched shows. In this context, the list of previously watched shows serves as part of the program's:

  1. user interface
  2. output
  3. prior state (correct answer)
  4. event trigger

Explanation: The recommendations (output) are based on data from past interactions, which constitutes the program's prior state. This historical data influences the current output, distinct from any immediate input. A is the visual layout, not the data. B is the recommendation itself, not the data used to generate it. D is an action that initiates a process; the viewing history is the data used in that process.

Question 24

A school network deploys educational software to aid remote learning across several grade levels. The program provides interactive lessons with short checks for understanding, then uses student responses to select follow-up practice. It keeps a limited log of learning events, including attempts, time on task, and which hints were used, and it updates a skill profile over time. Teachers, tutors, and curriculum leaders use summaries to identify common misconceptions and adjust live instruction accordingly. Students see progress indicators designed to motivate steady effort rather than competition. During development, students and families gave feedback that excessive tracking felt intrusive, so the team restricted collection to what supports learning and removed older details when no longer needed. The program’s purpose is to make remote instruction more responsive while respecting user concerns.

Based on the passage, what purpose does the program serve in its context of use?

  1. It primarily benefits software engineers by generating debugging logs, even if students receive no personalized instruction.
  2. It makes remote learning more responsive by tailoring practice from learning data while keeping tracking limited for families. (correct answer)
  3. It manages real-time game outcomes and player messages, aiming to maximize competition and rapid match turnover.
  4. It serves as a general surveillance tool, collecting unrelated personal details to predict behavior outside schoolwork.

Explanation: This question tests understanding of a computer program's function and purpose in creative development contexts (AP CSP). Understanding program function involves recognizing what the program does, while purpose relates to its intended outcome and impact on users. In this passage, the program provides interactive lessons across grade levels, uses student responses to select follow-up practice, and respects privacy concerns by limiting data collection. Choice B is correct because it captures the program's purpose: making remote learning more responsive through tailored practice while keeping tracking limited to address family concerns about privacy. Choice D is incorrect because the passage explicitly states the team restricted collection to learning-related data and removed older details, contradicting surveillance or unrelated data collection. To help students: Identify both the functional aspects and the broader purpose or goals stated in the passage. Practice recognizing how programs balance functionality with user concerns like privacy.

Question 25

Refer to the text: in genome sequencing, distributed nodes communicate via network messages, unlike tightly coupled parallel processors. What is a key difference between parallel and distributed computing?

  1. Distributed systems usually require message passing, while parallel systems often use shared memory or fast links. (correct answer)
  2. Distributed systems cannot scale, while parallel systems scale indefinitely without coordination.
  3. Parallel systems communicate only through the public internet, while distributed systems never communicate.
  4. Parallel computing is defined as any computing that uses electricity, unlike distributed computing.

Explanation: This question tests understanding of communication differences between parallel and distributed computing architectures. Parallel computing typically uses shared memory or fast interconnects for processor communication within a single system, while distributed computing relies on network message passing between separate nodes. In this passage, genome sequencing explicitly contrasts distributed nodes communicating via network messages with tightly coupled parallel processors. Choice A is correct because it accurately identifies this key distinction—distributed systems require message passing while parallel systems often use shared memory or fast links. Choice C is incorrect because it makes false claims about communication methods—parallel systems don't exclusively use public internet, and distributed systems must communicate to function. To help students: Create comparison charts showing communication methods for each architecture. Emphasize that communication method follows from physical architecture—close processors can share memory, distant nodes cannot. Watch for: oversimplification of communication patterns or absolute statements about what each system can or cannot do.