Edexcel GCSE Computer Science (1CP2) Exam Questions

• C 128 (1)
• The only correct answer is C. The correct answer is 128.
• A is not correct because 6 bits give only 64 different combinations
• B is not correct because 127 is the largest 7-bit value, not the number of characters that 7 bits can represent
• D is not correct because 256 characters need 8 bits, as used by 8-bit extended ASCII

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

• Version B has more pixels in the same area (1) so each pixel represents a smaller part of the image (1)
• Version B has a higher pixel density (1) so finer detail can be represented (1)
• The pixels in Version B are smaller (1) so more detail can be captured in the same space (1)
• Version B has a higher resolution (1) because there are more pixels per unit of area (1)

For both marks, the expansion must follow/associate with the statement.

Do not accept 'more pixels' on its own without saying same area/pixel density/smaller pixels.

Do not accept higher colour depth or more colours.

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

• Each sample is stored using more bits (1) so the amplitude can be recorded more precisely (1)
• More different amplitude values can be represented (1) because each extra bit doubles the number of possible values (1)
• The height of the wave at each sample point is measured more accurately (1) so the digital wave is closer to the analogue wave (1)
• The gap between the true amplitude and the stored value is smaller (1) because there are more values for the sample to be rounded to (1)

For both marks, the expansion must follow/associate with the statement.

Do not accept 'the sound is sampled more often' or 'more samples are taken per second', as these describe the sample rate, not the bit depth.

Do not accept 'the file size increases' on its own as an effect on the representation of the sound.

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.