IB Computer Science Case study 2020-21: Exam Questions

Case Study November 2020: QN MS

6 flashcards · Computer Science · by 5umrr

  1. Identify two characteristics of a peer-2-peer (P2P) network. [2]

    No centralized administration for the network/decentralized network; Network is more resilient to failure;

  2. Identify two sources of entropy. [2]

    atmospheric noise; radioactivity; thermodynamics; Brownian motion of particles; mouse movements; algorithmic sources;

  3. Describe the steps that need to be carried out by the blockchain system to find a user’s current MONS balance. [4]

    Balances are not stored in the blockchain/calculated in real time; A digital signature/hash address is used to identify the user; An algorithm must go through the entire blockchain examining all transactions that match the signature/address; Relevant transactions debits and credits are added to calculate the balance; Third party services are available to monitor the blockchain and provide a balance for the specified addresses; It is likely that the wallet (app) will regularly compute the balanc…

  4. Dolores states, “one of the great things about the blockchain is that we can ensure that the solution time remains at 10 minutes, and we can do this even as the number of MONS miners increases” (lines 63–65). (b) Explain why it is important to ensure the solution time remains at 10 minutes. [4]

    Proof of work delays the creation of new blocks and therefore avoid spamming and/or instant re-writing of the blockchain; A certain amount of time is required to make sure that there are not too many blocks mined; If mining takes much longer than 10 minutes, it may discourage miners from mining If mining takes much longer than 10 minutes it may make cryptocurrency transactions too slow; Miners are required by the network so therefore a balance must be found which takes miners with standard hard…

  5. Critics have complained about the potential environmental effects caused by the computing resources required by a blockchain network. Analyse the potential effects that the use of MONS could have on the environment. [6]

    Negative impacts on the environment: Miners which work on the network require energy to process proof of works; Farms of miners will need energy for cooling systems such as AC, which have negative environmental results (e.g. greenhouse gases); The use of computers to maintain the network may result in e-waste, which would be detrimental to the environment; The mining of raw materials for electronic products (e.g. silicon, aluminum, copper, lead, and gold) can damage natural habitats for animals…

  6. Pablo states: “In a traditional banking system, users trust the banks to keep everyone’s money safe; but with MONS, the whole blockchain, right from the very first transaction, would be visible to all MONS users, so it is important to be able to explain to citizens how their money is guaranteed to be safe” (lines 109–112). With reference to the key technologies, to what extent do you believe the MONS project will ensure the safety of the residents’ money? [12]

    Security features All transactions are recorded into files called blocks. Each block contains a hash of the previous block as well as some transactions. Every transaction is visible to everyone, which makes it difficult to change existing data which may be replicated on thousands of computers (decentralisation). Any change to any historic transaction would be noticeable because the hashes of all subsequent blocks would not agree. Transactions are confirmed many times (consensus control). The mo…