Computer science · 2014 · November · Paper 2 · HL · Question paper

8814-7012 18 pages N14/4/COMSC/HP2/ENG/TZ0/XX Tuesday 18 November 2014 (morning) Computer sCienCe HiGHer level paper 2 INSTRUCTIONS TO CANDIDATES • Do not open this examination paper until instructed to do so. • Answer all of the questions from one of the Options. • The maximum mark for this examination paper is [65 marks]. o ption Questions Option A – Databases 1–4 Option B – Modelling and simulation 5–8 Option C – Web science 9–13 Option D – Object-oriented programming 14–17 1 hour 20 minutes © International Baccalaureate Organization 2014 88147012 8814-7012 – 2 – N14/4/COMSC/HP2/ENG/TZ0/XX Option A — Databases 1. (a) (i) Describe, with the use of an example, the difference between an operation and a transaction. [3] (ii) Identify a reason why a transaction may need to be rolled back. [1] (iii) State the effect of rolling back a transaction. [1] A database is to be used by a small bank to process deposits, withdrawals, account balance enquiries and the creation of new accounts. (b) Outline two reasons for using a database for this application. [4] (c) Explain, with examples, how this application might use data validation and data verification in processing a deposit. [4] (d) Discuss, with an example, the importance of isolation (the ACID property) in this application. [3] 2. A company sells handmade hats online. They plan to introduce a database management system (DBMS) which is to be used as part of their online shop. The data the company stores for each hat are: size, price and the name of the person who made the hat. (a) Identify the data types for the data of each hat. [3] (b) Identify three capabilities that must be supported by DBMS tools. [3] One of the features of a DBMS is security. (c) For the scenario above, discuss two security features needed for this DBMS. [4] (d) Outline the nature of a data dictionary. [2] (e) Explain the importance of data modelling in the design of a database. [3] (Option A continues on the following page)