Edexcel GCSE Computer Science (1CP2) Exam Questions

• C No data is lost and the original file can be recreated (1)
• The only correct answer is C. The correct answer is no data is lost and the original file can be recreated.
• A is not correct because encryption hides data and does not make the file smaller
• B is not correct because permanently removing data is lossy compression
• D is not correct because splitting a file into packets is part of transmission, not compression

• C Tebibyte (1)
• The only correct answer is C. The correct answer is tebibyte.
• A is not correct because a gibibyte is 1024 mebibytes
• B is not correct because a mebibyte is 1024 kibibytes
• D is not correct because a terabyte is 1000 gigabytes

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

• Lossy compression permanently removes some data (1) whereas lossless compression does not remove any data (1)
• With lossy compression the original file cannot be recreated exactly (1) but with lossless compression it can (1)
• Lossy compression can produce a smaller file/a higher compression ratio (1) whereas lossless compression keeps all of the data so compresses less (1)

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

Allow 'removes data' for 'permanently removes data'.

A correct statement about only one type of compression, with no contrast, earns one mark.

Do not accept a reversed statement such as 'lossless compression loses data and lossy compression does not'.

Do not accept 'lossy makes the file smaller' on its own, because lossless compression also reduces the file size; the answer must say that data is removed.

Do not accept 'lossy is worse quality' on its own without saying data is removed.

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

• The capacity is easier to read/write (1) because a tebibyte is 1024^4 bytes so the same capacity in bytes would have many more digits (1)
• The number is shorter (1) because writing 16 TiB instead of 17 592 186 044 416 bytes uses far fewer digits (1)
• There is less chance of making a mistake when copying the value (1) because a long byte count of many digits is easy to mistype (1)

For both marks, the expansion must follow/associate with the statement and must refer to the number of digits/length of the value.

Allow 'fewer digits'/'shorter number'/'less chance of error' on its own for the first mark; the second mark needs the linked reason that a tebibyte is 1024^4 bytes, so the value in bytes would be very long/have many more digits.

Do not accept 'it is bigger'/'tebibytes are larger' on its own, as this does not give a benefit of using them.

Do not accept 'easier' on its own without saying what is easier, e.g. fewer digits/shorter number.

Do not accept 'because tebibytes are used for large storage' without a reason about the number of digits/readability.