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Date November 2019 Marks available 1 Reference code 19N.2.SL.TZ0.8
Level SL Paper 2 Time zone no time zone
Command term State Question number 8 Adapted from N/A

Question

The IB Coordinator of AB World Academy introduces the Extended Essay to the Grade 11 students in January by researching the difference between primary and secondary data on the internet.

Some of the students used the Google search engine (Google.com) and others used the Ask search engine (Ask.com). These search engines gave results.

Google uses the PageRank algorithm and Ask uses the HITS algorithm.

The IB coordinator uploaded the assignments onto a cloud-based Learning Management Platform.

As part of their research, students downloaded images from the internet. Most of the downloaded JPG images were compressed using lossy compression.

Define the term search engine.

[1]
a.

Distinguish between the principles of these two algorithms.

[4]
b.

Describe the difference between cloud computing and local client-server architecture.

[3]
c.

State the alternative type of compression to lossy.

[1]
d.i.

Evaluate the advantages and disadvantages for students of using compressed images in their IB Coursework.

[4]
d.ii.

A PNG image uses open standards.

Distinguish between interoperability and open standards.

[2]
e.

Markscheme

Award [1 max].
Software that interrogates a database of web pages;

a.

Award [4 max].
PageRank algorithm [2 max]
PageRank works by counting the number and quality of in links of a page to determine a rough estimate of how important the website is;
The assumption is that more important websites are likely to receive more links from other websites;
Pages are given a score (rank) / counts links per pages;

HITS algorithm [2 max]
Based on authorities and hubs;
Authorities: A page is called an authority, if it contains valuable information and if it is truly relevant for the search query. It is assumed that such a page has a high number of in-links;
Hubs: These are pages that are relevant for finding authorities. They contain useful links towards them. It is therefore assumed that these pages have a high number of out-links;

b.

Award [3 max].
Local client-server architecture [1 max]
The server is the central communicator between clients (e.g. email/chat server)/allows different clients to access and manipulate data;

Cloud computing [1 max]
Cloud computing puts the focus on sharing computing resources over the internet;

Differences between the two [1 max]
Cloud computing is often offered as a service to individuals and companies whereas local client server architecture is based at an organizational level;
Cloud computing can scale up or down depending on current demands more easily than local client server networks;
Client / server networks are more secure than the cloud as the data transmission is carried out locally;
Client / server networks have lower levels of latency than the cloud as the data transmission is carried out locally;

c.

Award [1 max].
Lossless (Compression);

d.i.

Award [4 max].
Advantages of using compression [2 max]
Allows for more rapid upload/download as the compressed file is smaller than the original;
Scrolling through the coursework may be quicker;

Disadvantages of using compression [2 max]
This may mean that the overall quality of the work is reduced;
This may be an issue when printing the work / or the quality of the image is a key contributor to the overall quality of the work;

Overall comment [1 max]
The impact of using compression may be dependent on the context in which the work is compressed;

d.ii.

Award [2 max].
Interoperability means a computer program can communicate and exchange information across a range of platforms;
Open standards are publically and free standards that enable interoperability;

e.

Examiners report

All candidates are familiar with search engines but not all were able to put together a precise definition that including both the role of the user and processes involved.

a.

This was a memory recall question and dependent on the schools' coverage of the course.

b.

Candidates did not answer this well being unable to clearly distinguish between the two types of architecture. They seemed particularly unaware of the difference in scale.

c.

This was a familiar topic and was answered well. Full marks went to candidates who related their answers to the specific scenario.

d.i.

This was a familiar topic and was answered well. Full marks went to candidates who related their answers to the specific scenario.

d.ii.

Another memory recall question at was answered quite well.

e.

Syllabus sections

Option C: Web science » C.3 Distributed approaches to the web
Option C: Web science

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