Edexcel GCSE Computer Science (1CP2) Exam Questions

• A 32 (1)
• The only correct answer is A. The correct answer is 32.
• B is not correct because 33 is the ASCII code for the exclamation mark (!)
• C is not correct because 48 is the ASCII code for the character 0
• D is not correct because 65 is the ASCII code for the uppercase letter A

Award one mark for any of the following:

• Only two different colours can be represented/stored (1)
• Each pixel can only be one of two values (1)
• The image can only be shown in black and white (1)

Allow answers that give the number of colours, e.g. two colours, 2 colours

Allow any pair of two colours, e.g. black and white, black and grey

Do not accept low resolution/poor quality/lower quality

Do not accept only one colour/can only show black

Do not accept 2 bits/2^1 without a statement about the number of colours that can be represented

Award up to two marks for a linked description such as:

• The bit depth is the number of bits used to store each sample/measurement (1) so a higher bit depth gives more possible/discrete values for the amplitude (1)
• A higher bit depth records the amplitude more accurately (1) because the stored value can be closer to the actual height of the wave (1)
• A low bit depth gives fewer possible amplitude values (1) so the amplitude is rounded to the nearest value, making the recording less accurate (1)

Do not accept sample rate/sample interval (number of samples per second) in place of bit depth.

Do not accept 'more bits gives better quality' or 'more accurate' on its own, without a development linked to the number of values or the amplitude stored.

Do not accept file size on its own, and a file size point cannot earn the second mark, as it does not describe the stored value.

Indicative content

What resolution means

• Resolution is the number of pixels in the image, or the number of pixels per inch.
• A photograph that is 6000 × 4000 pixels has a higher resolution than one that is 600 × 400 pixels.
• Resolution is not the same as colour depth or the number of colours.

Effect on detail

• A higher-resolution photograph has more pixels in the same area, so it can show more detail.
• A low-resolution photograph printed across a full page will look blocky or pixelated because each pixel is enlarged.
• A small website thumbnail uses fewer pixels on screen, so a lower-resolution version may still look sharp.
• A high-resolution original can be cropped and still contain enough pixels for a full-page print.

Effect on file size

• More pixels means more binary values must be stored, so the file is larger.
• A large file takes more storage and is slower to upload or download, which matters for visitors to the website.
• The photographer could make a lower-resolution copy for the website and keep the high-resolution original for print.
• File size also depends on the colour depth and the file format or compression used.

Levels

• Level 0 (0 marks): No rewardable content.
• Level 1 (1–2 marks): Basic, independent points are made, showing elements of understanding of key concepts/principles of computer science. (AO1) The discussion will contain basic information with little linkage between points made or application to the context. (AO2)
• Level 2 (3–4 marks): Demonstrates adequate understanding of key concepts/principles of computer science. (AO1) The discussion shows some linkages and lines of reasoning with some structure and application to the context. (AO2)
• Level 3 (5–6 marks): Demonstrates comprehensive understanding of key concepts/principles of computer science to support the discussion being presented. (AO1) The discussion is well developed, with sustained lines of reasoning that are coherent and logically structured, and which clearly apply to the context. (AO2)

Level 3 responses must cover both detail and file size.

Do not accept resolution as the number of colours.