2010 AS Computer Applications (Marking Sheme & Candidates' Performance)

8/7/2019 2010 AS Computer Applications (Marking Sheme & Candidates' Performance)

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Marking SchemeThis document was prepared for markers' reference. It should not be regarded as a set of model answers.Candidates and teachers who were not involved in the marking process are advised to interpret its contents with care.In questions asking for a special number of reasons or examples etc. to be given and a candidate gives more than thatis required, the surplus answers will not be marked. For example, in a question asking for two examples to be givenand three are given by a candidate, then only the fust two answers will be marked.

Paper I1. (a)

(b)

3. (a)

(c)

(d)

(c)(d)

All the sequences.Due to various reasons,paths.Data bits and checkingprocedures.

bits are coffupted in such a paltern that they can bypass the validation

No, one of the main tasks for routers is to avoid looping.Yes, a hub broadcasts all the incoming data and therefore the packets will be received by bothChristine's and Michael's computers.

MarksIpacket switching networks allow packets to be routed through different I

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2. (a) (i) Columns / Textbox(iD Automatic text flow among columns during text editing. / Free positioning.

(b) Due to the compatibility of different versions of the word processing software.(c) The object is inserted using links (OLE).

(b)(c)

4. (a)(b)

(d)

create index MCODE Ion MEM(GRAD YEAR, NAME)To improve the searching speed when GRAD_YEAR is the searching key.- Slow down transaction as indices need to be rebuilt during add, delete and update operations.- Index files use up extra storage spaces.Boolean and Memo.Because indexing on these data types will not significantly improve searching speed.

cross-over UTP cable- Wi-Fi / blue-tooth / other wireless network connection- flash memory card or device / other tlpe of removable storage devices- Any IP address of the same net: 192.168.10.x (x + 0,10,255)- A subnet mask of 255.255.255.01255.255.254.0The access right of the file in Kathy's computer is not properly set.

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5. (a) (i) A. coDE vs B. coDEM01 vs M01Y102 vs M01M02 vs M02M03 vs M03M03 vs M01M03 vs 1402

(ii) where A.CODE < B.CODE(b) sel-ect A.CODE, 'vs', B.CODE from BADMINTON A, BADMINTONwhere A.CODE < B.CODE and (A.SEED or B.SEED)(a) (i) The file size is very large which may exceed the mailbox limit.

(iD Authentication by digital signature.(b) (D To veriff sender's identity.(ii) sender's public key

(iii) name of the certificate authority

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7. (a) RAMIncrease the size of RAM can decrease the time needed to access the relatively slower secondarystorage devices.CPU. Powerful CPU can increase the number of instructions executed per unit of time.Advantage: Much faster seek timeDisadvantage: Relatively much smaller capacity than magnetic hard disks- any two differences in the requirements or compatibility of hardware and software

sel-ect * from stud order by bdatedescselect class, year (bdate) as x, [+ from stud]count ( * )from stud

(b)(c)

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(d)

8. (a)(b)

group by class, x(c) update studset grade :rClwhere year (bdate) >1995 or(year(bdate):1995 and month(bdate)>9) or(year(bdate):1995 and month(bdate):9 and day(bdate) >1)All Correct in the where

select s.scode, name from stud s, event e, plist pwhere s . scode _ p. scode and p. ecode : e. ecodeand ename - ' 15 0 0M ' and grade -- 'A'(d)

condition IIII

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Marks(e) (i) To list the number of students of each house participating in the event with event code u001. I

(ii) To list the house with the highest number of students participating in the event with event code IE001.(0 (i) inner j oin event eright Iouter] joinwhere s. scode not

( select scode from(ii) union / union all-

(b)

(c) (i)(ii)

(d) (i)

on p. ecode _ e. ecodestud s on p.scode - s.scodeinplist )IIIII

9. (a) (i) Incremental backup: may need to retrieve previous incremental backups in order to recoverFull backup: time consuming(iD To support data recovery. / Fault tolerance(iiD UPS (Unintemrptible Power Supply)

X: operating systemY web serverPhysical addressBecause physical address is unique and is set by the manufacturers.To act as the primary and the secondary DNS.The secondary DNS is the backup domain name server.- There is a network traffic jam.- There are many other processes running in the computer.

(iD The data volume is lower for voice.There is a mismatch between the plug-in player with the video file format.

(D Trace the IP address and determine the corresponding ISP to reveal the offender's identity.(iD - combination of alphanumeric and symbols- content-wise not easy to guess

satellites: unaffected by environmental factors such as earthquakeoptical fibers under the sea: more stable communication as not being affected by bad weather

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(e)(f)

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10. (a) (i) Sort the country code in Sheet 1.Marks

I2(ii) -l-ookup (D2, Sheetl !A$2zA$9, Sheetl !B$2:B$9)

(b) Firstly sort by Date of Birth and Name where Date of Birth is the primary key and name is the 2secondary key, then sort by Country Code.

(c) - (sum(C2:G2) -max (C2:G2) -min (C2:G2)) /3Use of large / sma LL / sum-max-min: I markCorrect numerator : 1 markAll correct: I mark

(d) :rank(H2,H$2:H$25)(e) (i) -use':and(B2:"CN",I2


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C andidates' PerformancePaper I

QuestionNumber Performance in General1 This question was poorly answered. Most candidates were not familiar with how packets aretransferred through a switch, router and hub. Many of them were not aware of bit-checking duringtransmission, while some wrongly assumed that packets would arrive at destination in the same order

as the original sequence or in reverse order.2 This question was well answered.their suggestions were better thanproblem" for part (b).

However, not manythe table feature. A candidates were able tofew candidates wrongly explain clearly howanswered "hardwareaJ This question was poorly answered. Many candidates were not familiar with the syntax of creatingindex files in SQL. A few candidates showed that they have the right concept of using index in

database file management but they were not aware of the disadvantage of creating individual indexfile for each of the fields. Many candidates did not realize a Boolean data field should not beindexed.4 This question was well answered. However, some candidates were not able to write down correctlythe name "crossover UTP cables". Most candidates did very well in the configuration of the IP

address and subnet mask for a computer in a network, but only a few candidates showed that theyhave the experience ofbeing blocked from accessing a file by different type ofaccess rights.5 This question was satisfactorily answered. Many candidates were able to identiff the unexpectedmatches but some of them were not aware that they were only required to write down the"unexpected" ones. Some candidates wrongly gave the answer "A.coDEB.coDE" for part(aXii).6 This question was fairly well answered. Most candidates demonstrated a good knowledge of using

FTP versus email for file transfer. However, some candidates wrongly considered that the purpose ofa digital certificate is to identify the recipients. Some candidates were not aware that the public keyas well as the name of the authentication authority are also stored in a digital certificate.

7 This question was well answered. Most candidates were familiar with the computer hardware and itsperipherals. However, a few candidates mixed up memory and storage device. Some candidates werenot aware that the size of cache memory cannot be easily increased while some others did notexplain clearly how upgrading CPU or the size of the memory could speed up a computer.8 This question was fairly well answered. However, many candidates were weak in handlingDATE/YEAR functions while some showed very limited experience of using UPDATE, JOIN or

UNION in SQL. Moreover, a few candidates wrongly used reserved word 'year' as the alias in thequery. Only a few candidates were able to use 'BDATE>ITT1/9/I'to calculate the age of thestudents. For part (e), some candidates wrongly described the operations of the given SQL statementsinstead of explaining the purposes of them.

9 This question was well answered. However, some candidates wrongly answered that incrementalbackup will easily cause data loss while some others were not aware of the complexity of therecovery process in incremental backup. Only a few candidates were able to state the reasons forusing RAID and setting two different addresses for the DNS server. For part (g), many candidatesignored the part of the question which stated'as the communication media'and therefore wronglycompared only wired and wireless communication.

10 This question was fairly well answered. However, many candidates only mentioned sorting in part(a)(i), without speci$ing the target column; while some others were not familiar with multi-columnsorting in part O). Many candidates were not aware of using Lookup function in part (a)(ii). Manycandidates were quite familiar with using functions like Large, Sma11, Max and Min and alsoexperienced in handling issues with absolute addressing. However, most candidates were weak inusing pivot table and sub-total features in spreadsheets.

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3.

4.

Paper 2 (SBA)General comments and recommendationsl. Most candidates were able to present the project systematically in their reports. However, many ofthem were weak in giving a clear and comprehensive discussion and conclusion. A few were not able to

state task-specific objectives.2. Regarding the Sports Day System, some candidates did not conduct a feasibility study on the proposedsystem. Other candidates were not able to describe it clearly and justifr their database design for the

system.Some candidates failed to apply the knowledge they had learnt in the curriculum, especially inanalyzingsoftware and hardware requirements of a Public Wi-Fi system.Most candidates were good at proposing functions that facilitate database management.

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2010 AS Computer Applications (Marking Sheme & Candidates' Performance)