📝 Exam Questions — Computer Science

File compression is a technique used to reduce the size of data files, making them easier to store and transmit. There are different methods of compression, each with specific characteristics and applications. (a) Define the term 'lossless file compression'. [2] (b) Define the term 'lossy file compression'. [2] (c) Identify two types of files that typically use lossless compression. [2]

Run-Length Encoding (RLE) is a lossless data compression technique that reduces the physical size of a file by storing sequences of identical data values as a single data value and its count. Fig 1.1 shows a simple black and white image represented by a grid of pixels. (a) Describe how Run-Length Encoding (RLE) would be applied to compress this image row by row. [4] (b) Analyse the effectiveness of RLE for an image that is highly detailed with very few repeating pixel sequences. [3] (c) Evaluate one advantage and one disadvantage of using RLE for compressing coloured images compared to black and white images. [3]

Computers store and process information using the binary number system. Understanding how to convert between binary and denary is fundamental to working with computer data. (a) Convert the denary number 75 into an 8-bit binary number. [2] (b) Convert the binary number 10110101 into its denary equivalent. [2] (c) State the largest denary number that can be represented using 8 bits. [2]

Digital media formats like MP3 and MP4 have become standard for storing and distributing audio and video content. (a) State the primary purpose of MP3 files. [2] (b) Describe two key differences between MP3 and MP4 file formats, focusing on the types of data they typically store. [4]

Computers process and store information in a digital format, distinct from the analogue signals found in the natural world. (a) State two fundamental differences between analogue and digital data. [2] (b) Identify three everyday examples of digital data. [3]

Number systems are fundamental to how computers store and process data. One such system is Binary-Coded Decimal (BCD). (a) Define Binary-Coded Decimal (BCD). [2] (b) Convert the denary number 873 to its 12-bit BCD equivalent. [4]

When a computer program encounters a critical error, it may generate a memory dump. This is a snapshot of the contents of the computer's memory at the time of the crash. (a) Analyse the purpose of a memory dump and why it is displayed in hexadecimal format. [4] (b) A section of a memory dump shows the hexadecimal value 41. Convert this value to its ASCII character equivalent and then to binary. [3] (c) Explain how a programmer might use a memory dump to debug a software error. [3]

Modern computer applications often integrate various forms of content to enhance user experience. (a) Define the term 'multimedia'. [2] (b) Identify three common types of media that are typically integrated into a multimedia presentation. [3]

A digital clock or calculator often displays numbers in denary format, requiring constant conversion if internal calculations are performed in pure binary. Binary-coded Decimal (BCD) is an alternative number system sometimes used in these devices. (a) Explain why BCD is often used in digital clocks and calculators, despite being less efficient than pure binary for storing numerical values. [4] (b) Identify two specific scenarios where BCD's direct mapping to denary digits is advantageous, providing a brief justification for each. [4]

Computers represent all data using binary digits. Understanding how these fundamental units are structured is crucial for processing information. (a) Define the term 'bit' in the context of data representation. [2] (b) Draw a simple diagram to show how the denary number 5 can be represented using 4 bits. [3] (c) Explain how increasing the number of bits used to represent data affects the precision or range of values that can be stored. [3]

Binary-coded Decimal (BCD) is a system where each denary digit is represented by its own 4-bit binary code. Fig 1.1 illustrates the BCD representation of a two-digit denary number. Fig 1.1 (a) Convert the denary number 149 to its 12-bit BCD equivalent. [3] (b) Show the BCD representation of the denary number 52, as depicted in Fig 1.1. [3] (c) Calculate the largest denary number that can be represented using 16 bits in BCD. [3]

Binary numbers are fundamental to how computers store and process data. Operations like addition and subtraction are performed at this low level. Fig 1.1 shows two 8-bit binary numbers aligned for addition. Number 1: 0 1 1 1 0 1 0 1 Number 2: 0 0 1 0 1 0 1 1 ----------------------------- Carries: _ _ _ _ _ _ _ _ Sum: _ _ _ _ _ _ _ _ (a) Perform the binary addition of 01110101 and 00101011, showing any carries in the designated row. Represent your answer as an 8-bit binary number. [4] (b) Identify the denary equivalents of the two binary numbers from part (a) and the denary equivalent of your answer. [3] (c) Explain the significance of the carry bit in binary addition operations. [3]

Digital images are fundamental to modern computing, with coloured images requiring specific methods for storing and displaying a wide range of hues. (a) Explain how colour depth affects the quality and file size of a coloured image. [3] (b) A coloured image has a resolution of 1920 x 1080 pixels and a colour depth of 24 bits. Calculate the uncompressed file size in megabytes (MB). [3] (c) Describe one method used to represent colour in digital images, other than simply storing the colour depth for each pixel. [2]

Different number systems are used in computing for various purposes, each with its own advantages and applications. (a) Explain why different number systems are used in computing, with reference to human readability and machine processing. [3] (b) Describe the term 'base' as it applies to number systems, using an example. [3] (c) Give an example of a number system with a base greater than 10, apart from hexadecimal. [2]

Digital video plays a crucial role in modern communication and entertainment, but its storage and transmission require significant data handling. (a) Outline how a digital video is constructed from individual frames. [3] (b) Explain the relationship between resolution, colour depth, and frame rate on the overall quality and uncompressed file size of a video. [4]

File compression is an essential technique in modern computing, helping to manage storage and transmission of digital data. (a) State two reasons why file compression is used. [2] (b) Explain the difference between lossless and lossy file compression. [4]

Digital images form a fundamental part of multimedia content. The way images are stored and processed depends on their characteristics, such as colour depth and resolution. (a) Explain the concept of 'bit depth' in the context of image representation, specifically for black and white images. [3] (b) Discuss the advantages and disadvantages of using black and white images compared to colour images in digital applications, considering factors beyond just file size. [4] (c) A black and white image has a resolution of 640 x 480 pixels. Calculate the total file size in kilobytes (KB), assuming 1 KB = 1024 bytes. [3]

Computer graphics can be represented in different ways, including vector graphics and bit-map images. (a) Define the term 'vector graphics'. [2] (b) Identify two common properties that are stored for a line segment in a vector graphic. [2] (c) State one typical application where vector graphics are preferred over bit-map images. [2]

Digital media files, such as images, audio, and video, often require compression for efficient storage and transmission. (a) Compare the characteristics and suitable applications of lossless and lossy file compression methods. [5] (b) Discuss the impact of using MP3 compression on the quality and file size of an audio recording, explaining the underlying principle of perceptual music shaping. [5]

The binary number system is the foundation of all digital computing. Understanding its conversion to and from denary, and its limitations, is crucial. (a) Convert the denary number 157 to an 8-bit binary number. [3] (b) Convert the 8-bit binary number 10110110 to its denary equivalent. [3] (c) Explain why 8-bit binary numbers have a limited range for positive integers and calculate this range. [4]

Vector graphics are widely used in design and illustration due to their scalability. (a) Explain how a circle is represented in a vector graphics file. [3] (b) Describe the effect of zooming in on a vector graphic image. [2] (c) Sketch a simple diagram showing how two vector shapes, a rectangle and a triangle, could be layered to form a house-like image. Label the key components. [3]

Bit-map images are widely used for photographs and complex graphics due to their ability to represent intricate details. However, their quality can be significantly affected by how they are created and displayed. (a) Discuss the impact of image resolution and pixel density on the perceived quality of a bit-map image when viewed on different screen sizes. [4] (b) Sketch a small 4x4 grid representing a simple black and white bit-map image and shade the pixels to represent the letter 'L'. [3] (c) Explain why bit-map images often suffer from pixelation when scaled up significantly. [3]

The hexadecimal number system is widely used in computing to represent binary data more concisely. (a) Convert the hexadecimal number 3F8 to its denary equivalent. [3] (b) Identify two common uses of the hexadecimal number system in computing. [3]

Run-Length Encoding (RLE) is a lossless compression technique that can be applied to both text and image data. (a) Describe how Run-Length Encoding (RLE) is typically applied to image data. [2] (b) Fig 1.1 shows a single row of pixels in a black and white image. WWWWBBWWWBBB Apply RLE to the first row of pixels shown in Fig 1.1. Assume 'W' represents white and 'B' represents black. Show the compressed output. [4] (c) Calculate the number of bytes saved by compressing the row in Fig 1.1 using RLE, assuming each original pixel takes 1 byte and each RLE pair takes 2 bytes. [2]

Digital cameras capture images which are then stored as bit-maps on a computer. (a) Calculate the file size in megabytes (MB) of a bit-map image with a resolution of 1920 x 1080 pixels and a colour depth of 24 bits. Show your working. [4] (b) Discuss two factors, other than resolution and colour depth, that can affect the actual file size of an image stored on a computer, explaining how each factor influences the size. [6]

Digital images are fundamental to modern computing, but they can be represented in different ways, each with distinct advantages and disadvantages. Two primary methods are bit-map images and vector graphics. (a) Describe how a bit-map image is represented digitally. [3] (b) Compare the storage requirements and scalability of vector graphics and bit-map images. [4] (c) A company needs to design a new logo that will be used on everything from business cards to large billboards. Justify whether vector graphics or bit-map images would be more suitable for this task. [3]

Digital images are represented using pixels. The way these pixels are stored affects the image's file size and quality. (a) State the number of bits required to represent each pixel in a black and white image. [1] (b) Explain why black and white images are often chosen for applications where storage space or transmission bandwidth is limited. [2] (c) Calculate the file size in bytes for a black and white image with a resolution of 100 pixels by 50 pixels. [2]

The binary number system forms the basis of all digital computing. Understanding its structure, particularly positional weighting, is crucial for data representation. (a) Convert the denary number 137 into an 8-bit binary number. [3] (b) Convert the 8-bit binary number 11010110 into its denary equivalent. [3] (c) Draw a simple diagram to illustrate the concept of positional weighting in the binary number system, using a 4-bit example. [4]

Modern computers often use solid-state drives (SSDs) for storage due to their speed and durability. (a) A solid-state drive (SSD) has a capacity of 2 TB. Calculate this capacity in bytes, showing your working. [4] (b) Explain the difference between a kilobyte (KB) and a kibibyte (KiB) in terms of their values and why this distinction is important in computer science. [4]

Run-Length Encoding (RLE) is a lossless data compression technique that can be applied to text data to reduce its storage size. (a) Outline the steps involved in decompressing a text string that has been compressed using Run-Length Encoding. [3] (b) Draw a flowchart to represent the RLE compression process for a given text string, clearly showing input, processing steps, and output. [3] (c) Analyse a situation where RLE might not be effective for compressing text data, providing an example. [2]

Digital cameras capture and store images as bit-maps. The size of these image files depends on factors such as resolution and colour depth. (a) A camera captures an image with a resolution of 4000 x 3000 pixels and stores it with a colour depth of 16 bits. Calculate the file size of this image in kilobytes (KB). [4] (b) Determine the maximum number of distinct colours that can be represented by a colour depth of 8 bits. Show your calculation. [4]

Hexadecimal is often used as a shorthand for binary sequences in computing. (a) Convert the binary number 1011010111001010 to its hexadecimal equivalent. [4] (b) Explain how hexadecimal is used in memory dumps, referring to the advantages it offers over binary representation for this purpose. [5]

Number systems are fundamental to how computers store and process data. Programmers often use hexadecimal for convenience. (a) Convert the binary number 10110011 to its hexadecimal equivalent. [2] (b) Convert the hexadecimal number 7D to its binary equivalent. [2] (c) State why hexadecimal is often preferred over binary for representing large numbers in computing. [2]

Bit-map images are widely used for photographs and complex graphics, storing image data as a grid of individual picture elements. (a) Define the term 'pixel' in the context of bit-map images. [2] (b) Calculate the file size in megabytes (MB) for a bit-map image with a resolution of 3840 x 2160 pixels and a colour depth of 24 bits. Show your working. [4] (c) Explain how increasing the colour depth of a bit-map image affects its visual quality and file size. [3]

Run-Length Encoding (RLE) is a simple lossless data compression technique that can be effective for data with long sequences of identical values. (a) Apply Run-Length Encoding (RLE) to the following sequence of text data: AAAAAABBBCCCDDEEEEE. [3] (b) Explain why RLE is considered a lossless compression technique. [3] (c) Calculate the compression ratio achieved by RLE for the data in part (a), assuming each original character takes 1 byte and each RLE pair (count, character) takes 2 bytes. [2]

Two's complement is a standard method used by computers to represent negative numbers and perform subtraction using addition logic. (a) Perform the binary subtraction 01101001 - 00101100 using two's complement. Show all steps. [4] (b) Convert the denary number -45 into an 8-bit two's complement binary number. [2] (c) Explain why two's complement is preferred over one's complement for representing negative numbers in computer systems. [4]

Bit-map images are a common way to represent graphical data. Fig 1.2 shows a small, low-resolution bit-map image that has been significantly enlarged. (a) State the definition of a pixel. [2] (b) Explain why a bit-map image can appear 'pixelated' when it is significantly enlarged. [5]

Video files are composed of a sequence of images (frames) displayed rapidly. The quality and size of a video file depend on several factors, including resolution, colour depth, and frame rate. (a) Explain what is meant by 'frame rate' in the context of video. [3] (b) A video uses a resolution of 1920 x 1080 pixels, a colour depth of 24 bits, and a frame rate of 30 frames per second. Calculate the uncompressed file size in Gigabytes for a 5-minute video. Show your working. [5]

Images on computer screens are often stored as bit-maps, where each pixel's colour is represented by a binary code. Fig 1.1 shows a small section of a bit-map image. (a) Interpret the colour depth from the provided image data in Fig 1.1. [2] (b) Using the data from Fig 1.1, calculate the total number of unique colours that can be represented by the image. [4] (c) Explain how increasing the resolution of a coloured image, while keeping the colour depth constant, affects its file size and visual quality. [3]

The hexadecimal number system is widely used in computer science for various purposes due to its efficiency in representing binary data. (a) Explain two common uses of the hexadecimal number system in computer science, other than memory dumps. [3] (b) Identify the hexadecimal colour code for pure red. [2] (c) A memory address is given as F0A9 in hexadecimal. If the next address is F0AA, calculate the denary difference between these two addresses. [3]

Character encoding systems are fundamental to how computers represent and process text. ASCII was an early standard, but Unicode has largely superseded it. (a) Compare ASCII and Unicode in terms of the number of characters they can represent and their primary purpose. [4] (b) Explain why Unicode was developed as a successor to ASCII. [3] (c) State the relationship between the first 128 Unicode characters and the ASCII character set. [3]

Digital sound recording involves converting analogue sound waves into a digital format. This process requires decisions about how the sound is sampled to achieve a desired quality and file size. (a) Explain the terms 'sampling rate' and 'sampling resolution' in the context of digital sound recording. [3] (b) A sound file is recorded with a sampling rate of 44.1 kHz and a sampling resolution of 16 bits. Calculate the file size in megabytes for a 3-minute stereo recording. Show your working. [4] (c) Briefly discuss one advantage of increasing the sampling rate when recording sound. [2]

Binary addition is a fundamental operation performed by the Arithmetic Logic Unit (ALU) within a computer's Central Processing Unit (CPU). (a) Perform the binary addition of 01011010 and 00110111. Show your working. [4] (b) Explain what happens if the result of a binary addition exceeds the number of bits available, using an example. [4]

Computers process information using the binary number system. Fig 1.1 shows a table of denary numbers and their 4-bit binary equivalents. **Fig 1.1**

(a) Identify the binary value corresponding to the denary number 7 from the table. [2] (b) Determine the denary equivalent of the binary number 1101, showing your working. [3] (c) Explain the pattern observed in the binary representation as the denary numbers increase, and how this relates to powers of two. [4]

Digital images are fundamental to modern computing and are represented in various ways. Fig 1.1 shows a magnified section of a bit-map image. (a) Explain how a bit-map image is represented digitally. [4] (b) Describe the impact of increasing the colour depth of a bit-map image on its visual quality and file size. [4]

ASCII is a character encoding standard for electronic communication. It primarily represents text in computers, telecommunications equipment, and other devices. Fig 1.2 shows a partial ASCII table. Fig 1.2 (a) Identify the ASCII code (in denary) for the character 'A' and the character 'a' based on the provided ASCII table structure in Fig 1.2. [3] (b) Explain how the structure of ASCII codes, as partially shown in Fig 1.2, allows for efficient representation of English text, and why this becomes a limitation for other languages. [4]

File compression is a vital technique for managing digital data, allowing for more efficient storage and transmission. Various methods exist, each with its own strengths and weaknesses. (a) Apply Run-Length Encoding (RLE) to the following sequence of characters: AAAAABBBCCDDDAAAA [4] (b) Discuss the effectiveness of RLE for compressing images with large areas of solid colour compared to highly detailed, photographic images. [3] (c) Sketch a simple diagram showing how a file might be compressed and then decompressed, indicating where information might be lost in a lossy compression scenario. [2]

Digital media files are frequently compressed for storage and transmission, with different compression methods offering varying trade-offs between file size and quality. (a) Analyse the suitability of using lossy compression for a high-quality medical scan image compared to a video file for online streaming. [4] (b) Evaluate the impact of high compression ratios on the quality and usability of digital media. [3] (c) Explain how perceptual music shaping contributes to the effectiveness of audio compression methods like MP3. [3]

Fig 1.3 shows the relationship between 4-bit binary, hexadecimal, and denary values. (a) Convert the denary number 73 to its BCD representation. (b) Explain the key difference between BCD representation and converting a denary number directly to an 8-bit binary number. (c) Discuss one advantage of using BCD in specific applications, referring to its structure.

Fig 1.3 outlines a binary subtraction problem: 49 - 80. (a) Convert both 49 and 80 into their 8-bit two's complement binary representations. [4] (b) Perform the subtraction 49 - 80 using 8-bit two's complement binary addition. Show all working, including any carries, and the final 8-bit binary result. [4] (c) Justify whether the final result obtained in part (b) is correct, by converting it back to denary. [2]

Fig 1.4 shows a binary number to be converted to hexadecimal. (a) Convert the binary number 101111100001 from Fig 1.4 into its hexadecimal equivalent. Show your grouping of binary digits. [3] (b) Explain why grouping binary digits in fours is a convenient method for conversion to hexadecimal. [2]

Fig 1.2 refers to the subtraction of 95 - 68 in binary. (a) Convert the denary number 68 to its 8-bit two's complement binary representation. [3] (b) Using 8-bit two's complement binary addition, perform the subtraction 95 - 68. Show all working, including the 8-bit two's complement representation of 95 and the final binary sum. [3] (c) Explain how the most significant bit of your result in part (b) indicates the sign of the answer. [2]

Fig 1.1 shows the setup for the binary addition of two 8-bit numbers. (a) Perform the binary addition of 01010010 and 01000101, showing all carries clearly in the spaces provided. 0 1 0 1 0 0 1 0 + 0 1 0 0 0 1 0 1 ------------------- (b) Check your answer by converting the original denary values (82 and 69) and your binary sum to denary, and compare them.

Fig 1.1 shows the setup for a binary addition problem. (a) Perform the binary addition of 00100101 and 00111010, showing all carries clearly in the space provided in Fig 1.1. [3] (b) State the denary equivalent of the sum obtained in part (a). [2]

Fig 1.2 shows the relationship between 4-bit binary values, their hexadecimal equivalents, and their denary values. (a) Convert the hexadecimal value 'F' to its 4-bit binary equivalent using the information in Fig. 1.2. (b) Explain why hexadecimal is often used in memory dumps, as opposed to pure binary, referring to the relationship shown in Fig. 1.2. (c) A colour is represented by the hexadecimal value #FF00CC. Convert this hexadecimal value to its denary RGB components. Show your working for at least one component.

Fig 1.1 shows conversion methods for binary and hexadecimal numbers. (a) Convert the binary number 10000111111101 from Example 1.6 into its hexadecimal equivalent. Show all steps. (b) Convert the hexadecimal number 'A7' from Example 1.7 to its binary equivalent. (c) Describe one practical use of hexadecimal numbers in computer science, referring to the ease of conversion with binary.