Take this Exam: GCSE Computer Science: Data Representation | Zestly

Question 1

An eight-bit register currently holds the value 11111111. If the value 1 is added to this register, what occurs?

Accepted Answer

The result requires nine bits, causing an overflow error as the carry is lost.

Answer

The computer automatically expands the register to sixteen bits to accommodate the result.

Answer

The register resets to 00000000 without any error.

Answer

The register value becomes 100000000.

Question 2

In one character set the code for capital A is 65 and the code for lower-case a is 97. A student says this proves the computer remembers which letters are capitals. What does the case actually show about how text is stored?

Accepted Answer

That text is stored as numbers, and a character set is the agreed table saying which number stands for which character: capital A and lower-case a are different characters, so they have different numbers, and nothing else about the letter is stored at all.

Answer

That the computer stores letters as letters and keeps a separate marker recording whether each one is a capital.

Answer

That a capital letter takes more storage than a lower-case one, since ninety-seven is a larger number than sixty-five.

Answer

That each computer picks its own codes at random, which is why two machines can disagree about what a text file says.

Question 3

An image is 20 pixels wide by 30 pixels high and uses 3 bits per pixel. What is the total file size in bytes?

Accepted Answer

225 bytes

Answer

1800 bytes

Answer

600 bytes

Answer

5400 bytes

Question 4

A sound recording lasts 4 seconds, is sampled 8000 times per second, and each sample is 8 bits. What is the total file size in kilobytes (1 kilobyte = 1000 bytes)?

Answer

128 kilobytes

Answer

256 kilobytes

Answer

32 kilobytes

Answer

8 kilobytes

Question 5

A user has two files to make smaller: a spreadsheet of accounts, where every figure must come back exactly as it went in, and a photograph, where a small drop in quality would not be noticed. Which kind of compression suits each, and what does the lossy method actually do?

Answer

Lossy for both, since whatever was discarded is put back when the file is uncompressed.

Answer

Lossless for the spreadsheet and lossy for the photograph: lossless records the same data more efficiently, so the original can be rebuilt exactly, while lossy permanently throws away detail the eye or ear is least likely to miss, and that detail does not come back.

Answer

Lossless for both, since lossy compression only stores a file in a different format and nothing is ever actually lost.

Answer

Lossy for the spreadsheet and lossless for the photograph.