WJEC Computer Science 2016.

Hey, guys, I couldn't find a thread regarding the WJEC Computer Science exam on the 8th of June 2016, so I decided to make one. How's everyone's preparation and what 12 marker do you think will come up?

Reply 1

some-student

I'm doing the exam tomorrow too. I'm preparing by doing the past papers and using the mark schemes along with the booklet on their website and other websites like teach-ict.

For the 12 marker, I don't know but my teacher thinks that sampling will come up in some shape or form.

I also have AQA German tomorrow at 9am so we do the German first and then have to be put in a room until 1pm when we do the computing exam.

Good luck :smile:

Reply 2

keepyourapology

My teacher said that we might get a 12marker on DNS! So we should revise both topics in detail. xP Thankyou so much! And good luck for German, I know you'll ace it!

Reply 3

some-student

Original post by keepyourapology

My teacher said that we might get a 12marker on DNS! So we should revise both topics in detail. xP Thankyou so much! And good luck for German, I know you'll ace it!

Thanks! I'll revise DNS thoroughly then, but I might try and have a look at everything because the exams have been really unpredictable this year, and I really want to do well in computing because I would like to take it at uni.

Thanks so much for the good luck for German! :smile:

I'm sure you'll do brilliantly too. Best of luck for tomorrow and all your other exams :smile:

Hi, how was it? ^^

I had German & Computing today too! What a pain but I thought they both went okay
Does anyone know what the grade boundaries could be? And what they were in 2014,15?

Reply 6

some-student

Original post by keepyourapology

Hi, how was it? ^^

Original post by Learko

I had German & Computing today too! What a pain but I thought they both went okayDoes anyone know what the grade boundaries could be? And what they were in 2014,15?

Hi.

I found Computing quite hard although I feel like the quality of the paper this year was better than the previous years. I'm not too sure about the grade boundaries because I don't know how everyone else at my school found it.

German was also quite difficult but the reading was easier than the listening although I expect the grade boundaries to be quite high this year because most answers were multiple choice.

I might try and make an unofficial markscheme for the computing because I can't find any others.

How did you find it?

(edited 7 years ago)

Reply 7

keepyourapology

Original post by some-student

The quality was definitely a lot better than most years. I feel it was quite easy and there was a lot to write. Kids at my school thought the same, but I hope that I didn't make too many mistakes. The Welsh board is VERY specific on what they need.

Do you need my help to make the markscheme?

I'm glad that German didn't go terribly. I felt the same way for my French exam, so I'm sure everything will be fine, ngl. It's that thing with languages, it always feels like you've screwed up, but tbh, I'm sure you haven't.

I have Edexcel Math and AQA Economics tomorrow. Do you have any exams?

Reply 8

some-student

Original post by keepyourapology

I've made the majority of a markscheme so I will post it now and then will edit it bit by bit and your help will be much appreciated :smile:

I did French too and it was relatively harder than German. I agree that when you come out of the exam you feel bad but you probably have done better.

Tomorrow I have AQA maths calculator and then OCR chemistry on Friday.

Good luck for the rest of your exams :smile:

Reply 9

some-student

WJEC COMPUTER SCIENCE
UNIT 1 UNOFFICIAL MARK SCHEME
TUESDAY 8TH JUNE 2016
If you think I have made a mistake, feel free to tell me the answer because I might have got this wrong

1. Tick which of the below items are protocols [4] (not sure about the order of the list):
- P2P
- ISP
- ROM
- LAN
- TCP (1)
- IP (1)
- HTTP (1)
- FTP (1)

2. List four components of the CPU and describe their function [8]
only four of the five are needed
component: controller (1)
function: manages the execution of instructions (1)

component: Arithmetic Logic Unit (ALU) (1)
function: processes and manipulates data / carries out mathematical calculations and logical operations (1)

component: internal memory (1)
function: fast access memory on the CPU (1)

component: registers (1)
function: fast access temporary data store (of data and instructions while instructions are processed) (1)

component: buses (1)
function: allow data to be transferred to different parts of the computer (1)

3. Describe the purpose of hardware ports and give an example [2]
purpose: to serve as an interface between the computer and other computers or devices (1)
example: any suitable example, e.g. HDMI port, USB port, audio in, audio out (1)

4. An architect company considers using cloud storage to store their plans instead of a hard disc
(a) Give two advantages of this [2]
any two of:
can be accessed anywhere in the world with an Internet connection (1)
collaboration (1)
buy as much space as you need (1)
multiple global backups (1)
less need for hardware or IT staff (1)

(b) Give a disadvantage of this [1]
any one of:
an Internet connection is not always guaranteed (1)
could be hacked (1)
servers may be in countries with inadequate DP legislation (1)
reliance on provider for safe storage of data and later retrieval (1)

5. Star network
The diagram was a central switch, to which workstations, labelled alphabetically, were connected by cables.
I made the diagram below myself after the exam so it may not be exactly what was on the paper

(a) Apart from what is in the diagram, describe the hardware needed to connect a workstation to the network [1]
Network Interface Card (NIC) (1)

(b) Explain how a packet is transmitted from Computer A to Computer D, to include the role of the switch [5]
this may not be what they are looking for
packet sent from Computer A into switch (1)
destination address of packet examined in switch (1)
packet 'switched' to port of computer D / direct connection made between computers (1)
packet only transmitted to the device needed reducing data collisions / making a faster network (1)
packet sent from switch to Computer D (1)

6. Programming terms
(a)(i) Name the error that unexpectedly causes the program to crash [1]
runtime error / execution error (1)

(a)(ii) Name the error that causes the wrong output [1]
logical error (1)

(b)(i) Name the error that is a mistake in the grammar of the language [1]
syntax error (1)

(b)(ii) When does this error occur? [1]
during syntax analysis of compilation (1)

(c)(i) Explain the benefits of using a library [4]
related private functions and subprograms are stored in the same location (1)
time is saved as the programmer can simply use the private functions and programs stored in a library (1)
subroutines contained in a library have already been tested, so they should work reliably and not need further testing (1)
programs will contain less code and will therefore be easier to maintain (1)

(c)(ii) Name the error when a library function is called incorrectly [1]
linking error (1)

7. Sampling
Given a graph with the amplitude on the side in denary. Samples stored as 4-bit binary numbers - 8 readings taken over 8 seconds

(a) Complete a table containing missing amplitudes and binary equivalents with workings [5]
I can't remember the values in the table and the marks may not be awarded for each column
for each correct column, award one mark (1)
all correct (5)

(b)(i) Number of bits to store file [1]
(8 * 4 =) 32 (1)

(b)(ii) Number of bytes to store file [1]
(32 / 8 =) 4 (1)

(c) Explain how the sampling rate would be affected if the file is made better quality [1]
It would increase; samples would be taken more frequently (1)

(d)(i) What would happen to the file size if the sampling rate was 10 samples per second, instead of one sample per second? [1]
It would be bigger (1)

(d)(ii) Number of bytes to store file with rate of 10 samples per second [2]
10 * 8 * 4 = 320 bits (1)
320 / 8 = 40 bytes (1)

8. Conversions
(a) Convert the denary 162 into hexadecimal [2]
workings but wrong answer (1)
A2 (2)

(b) Convert the hexadecimal 1E into denary [2]
workings but wrong answer (1)
30 (2)

9. Complete the truth table - third and fourth columns [4]
A / B / A OR B / NOT ( A OR B )
1 1 1 0 (1)
1 0 1 0 (1)
0 1 1 0 (1)
0 0 0 1 (1)

10. Four features of a GUI provided by the OS with examples for each [8]
one mark for each feature, one mark for each suitable example (many):
providing meaningful icons and menus (1)
e.g. the question mark icon representing a help function (1)

allowing creation of shortcuts (1)
e.g. placing a shortcut of the browser application on the home screen for quick access (1)

allowing copying, deleting, moving, sorting and searching of files or folders (1)
e.g. moving the shortcut to the browser application into the applications folder (1)

allowing easy navigation of folders (1)
e.g. using a file explorer, like 'Finder' on Mac OS X (1)

allowing the user to have more than one window open (1)
e.g. having a browser window and word processor window open at the same time (1)

allowing the user to switch or copy between windows (1)
e.g. copying an image from the browser into a word processed document (1)

providing a command line interface (1)
e.g. like the one provided in Microsoft Windows (1)

allowing access to system settings such as hardware (1)
e.g. using a memory manager for RAM (1)

allowing customisation of the desktop such as changing the desktop background or the layout (1)
e.g. setting the background to an image stored on the computer (1)

providing user with error, warning and help messages (1)
e.g. error message if a virus has been detected (1)

allowing intuitive interaction with interface (1)
e.g. by items glowing when hovered on by the pointer (1)

11. Outputs of the below algorithm when the value of M input is 3 [4]
I'm not sure if the algorithm was exactly this

startmainprog

p is integer
M is integer
i is integer

input M

for i = 1 to 4

    p = i * M
    output p

end for

endmainprog

3 (1)
6 (1)
9 (1)
12 (1)

12. Algorithm
(a) Two variables: give a suitable data type and a reason [4]
mean
data type: real (1)
reason: it holds a decimal value (division by 20) (1)

counter
data type: integer (1)
reason: it holds a whole number value (1)

(b) Difference between local variables and local static variables [2]
local variables only have a lifespan that lasts in their scope / sub-procedure in which they are declared (1)
local static variables have a lifespan that lasts the length of the program (1)

13. Name who may use a Command Line Interface (CLI) and three benefits of it [4]
user: computer technician / computer programmer (1)

benefits - any three of:
quicker to type commands (1)
quicker to input commands as shortcut keys can be used (1)
little memory and processing power needed compared with other interfaces (1)
little storage space is required (as there are no graphical images to store) (1)
experts who have memorised the commands find it very fast to use (1)

14. Compression
(a) Compare lossy and lossless in terms of file size and quality [2]
lossy produces a smaller file than lossless (1)
lossy produces a lower quality file than lossless (file can be restored to original quality in lossless) (1)

(b) Advantages of compressing image files [3]
any three of:
less storage space used (1)
less network traffic / fewer data collisions (1)
quicker file downloads (1)
web pages download more quickly (1)
quicker file uploads (1)

(c) Metadata in image files [2]
any two of:
colour depth (1)
dimensions (width/height) (1)
location where the image was taken (1)
date when the image was taken (1)
resolution of image (1)
but not size

15. [QWC 10]
Scoring responses not sure about this
Top marks (about 8 - 10 marks)
All marking topics covered in good depth
QWC is very good

Middle marks (about 5-7 marks)
Most/all marking topics covered in some depth
QWC may have faults

Low marks (about 1-4 marks)
Some marking topics covered in brief
QWC may be poor

No marks (0 marks)
Irrelevant or no content

Marking points
how the business ensures only employees can access the network
usernames and passwords
passwords must be strong e.g.non-alphanumeric characters

other methods of ensuring that employees access the right data
user access levels e.g. only boss being able to view salaries

encryption when sending data between computers on the network
binary key only known to sender and recipient, use of XOR gate at both computers

procedures for natural disasters
safety procedures
risk analysis
staff briefing
replacing hardware
backups

what they would do after a fire destroyed all hard-discs
safety procedures - ensuring everyone was safe and the fire had been stopped
replacing hardware - replacing all the hard discs destroyed by the fire
backups - backing up all the customer information, discussing how backups work, e.g. grandfather-father-son method

(edited 7 years ago)

Reply 10

keepyourapology

Original post by some-student

I've made the majority of a markscheme so I will post it now and then will edit it bit by bit and your help will be much appreciated :smile:

Alright, let me know when you post it, I'll share it with some friends.

And so have you! I hope you get a good German grade.

You too, good luck. :smile:

Reply 11

keepyourapology

Are you me? I literally wrote the exact things down for most of them!

2. ALU
Performs calculations and manipulates the data to give an output to the user.
Internal Memory
RAM (holds data files for programs that are currently being worked on), ROM (holds BIOS that is essential for startup)
Registers
Contains the information required for the processing of data, such as program instructions.
Buses
Address bus, required for retrieving the storage location of a particular piece of data, data bus, required for retrieving the data itself.

4.a. The advantages were:
Could be accessed from anywhere, as long as there was internet connection.
Buy as much as you use, so if they need 18GB, they buy 18GB of space. With HDDs, you get a set amount of space which they might use.
4.b. Disadvantage:
Could be hacked/Could be inaccessible from a place without internet.

5. a. Okay..so it's NIC, and I WROTE THAT, but I got confused because I thought it wanted ALL the hardware required..so I wrote Gateway, Hub, WAP, Router in brackets..

You missed out the algorithm question..it was there somewhere. I got 3,6,9 for the first one, and then I got Real and then Integer, and then I defined Local and Local Static Variable.

14. Lossy Compression has a bigger file size than Lossless but has better quality.

14.(b) Something about 3 different ways of compressing images? Idk..

15. Subject to examiner.

Reply 12

some-student

Original post by keepyourapology

Haha maybe!

I got some of the answers from the WJEC booklet so they aren't all my answers but I wrote quite a lot of mine.

Reply 13

some-student

Original post by keepyourapology

You missed out the algorithm question..it was there somewhere. I got 3,6,9 for the first one, and then I got Real and then Integer, and then I defined Local and Local Static Variable.

14. Lossy Compression has a bigger file size than Lossless but has better quality.

For the algorithm one, I agree with the data types, but I think the outputs produced had 12 aswell because it said for i = 1 to 4 which is inclusive of 4 I think from seeing other past papers, although I found it quite confusing.

And for the compression, I agree lossless has better quality, but I think lossy has a smaller file size because especially for images, it is hard for lossless to find patterns while lossy just discards the data.

But I may be wrong...

Thanks for the help - I will update my markscheme with it :smile:

Reply 14

keepyourapology

Original post by some-student

Oh yeah, shoot! Lossless has more file size than Lossy. xP Got confused!

Reply 15

some-student

Original post by keepyourapology

Oh yeah, shoot! Lossless has more file size than Lossy. xP Got confused!

I agree - it's very confusing especially under the pressure of an exam

Reply 16

keepyourapology

Original post by some-student

I agree - it's very confusing especially under the pressure of an exam

Well, I hope I didn't make that mistake in the real exam, it'd be a dumb way to lose marks.

Well, judging from the mark scheme, if I am ridiculously harsh, then I'll be getting about a 75-76, which is quite bad. Judging by past grade boundaries, that would be a high A. I hope that the examiner isn't harsh, because I've been taking marks off long questions just because I want to prepare myself for an A. :/ It sucks because it was a good exam, but I guess I'm an idiot.

Well, good luck! :smile:

Reply 17

some-student

Original post by keepyourapology

You're not an idiot :smile:

you just may have made some mistakes like everyone does. I don't know how the grade boundaries will turn out this year although they're really high for computing :frown:

You never know - you may get higher than that and there is also the other exam that could bring your grade up. Also the examiner may be nice.

I've completed the markscheme now.

Good luck in the rest of your exams :smile:

including your computing unit 2 exam.