Friday, February 13, 2015
COMPUTER STUDIES
Book: KEYBOARD
Chapter No :4 (Computer Virus)
Class 7-E
1. Fill in the blanks with the correct words.
a) Computer viruses can spread from one compute to another when infected files are
attached to a/an email.
b) Microsoft Office documents are vulnerable to macro viruses.
c) A worm can propagate itself without any user action.
d) You can prevent most virus infections by using a good antivirus program.
e) Virus definitions should be updated regularly so that the antivirus software can recognize
new viruses.
2. Write T for the True statement and F for the False one.
a) A virus can affect both software and hardware. False
b) A computer virus cannot infect files on write-protected discs like CD-ROMs. True
c) You should scan pen drives for viruses before using them. True
d) Spyware can steal and pass on confidential information stored on your computer. False
e) Spam is a type of virus. False
3. Write one word for each of the following.
a) The type of virus that infects files with extensions .COM, .EXE etc
b) The type of virus that infects data files
c) Beast is an example of this type of program
d) Any dangerous software
e) The database of viruses that antivirus software scans for
Program Virus
Macro Virus
Trojan Horse
Virus
Virus Defination
4. Answer the following.
a) What is a computer virus?
Answer : A computer virus is a software program that has the ability to make copies of
itself, and that attaches itself to other programs or files.
b) What can a computer virus do to your computer?
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Answer : A virus may or may not be destructive. In some cases, viruses can erase data or
corrupt programs on the computer. Viruses are written by programmers and are intended to
run on computer systems without the user’s knowledge.
c) Name the three types of viruses based on target. Give one example of each type.
Answer : The three types of viruses based on target are – i) Program virus. Examples : Acid
Rain, Alien.298, Amoeba.A, Sunday, Cascade virus etc; ii) Boot virus. Examples : Danish
Boot, Devil.941, Eek (b), Disk Killer, Michelangelo, Stoned virus etc.
iii) Macro virus.
Examples : Melissa, Concept, Nuclear etc.
d) Differentiate between program viruses and boot viruses.
Answer : The main difference between program virus and boot virus is that the program virus
infects program files on the other hand boot virus infects the boot records of hard disks and
floppy disks. The examples of program virus are – Sunday, Cascade etc. and the examples
of boot virus are – Disk Killer, Michelangelo etc.
e) How does a computer virus spread from one computer to another?
Answer : Computer virus spread from one computer to another by the transfer of infected data
through e-mails, pen drives, or other sources.
f) List four precautions for protecting your computer from virus infections.
Answer : Four precautions for protecting my computer from virus infections are –
i) Restrict access to my system, both offline and online.
ii) Only allow trustworthy users to use the system.
iii) Install and use antivirus software and keep it updated.
iv) Scan files that I download from the Internet.
g) List five different types of malware.
Answer : Five different types of malware are –
i) Worms
ii) Trojan Horses
iii) Spyware and
iv) Spam
h) What are virus definitions are why is it necessary to update them?
Answer : By virus definitions we mean the database of viruses that antivirus software scans for.
This database needs to be updated regularly, because new viruses are being developed and
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released all the time. If the virus definition file is not updated, antivirus software will not
know about new viruses and will not be about to catch them.
5. Choose the correct option.
a) Program virus infect program files with extensions such as
iv) All of these.
b) Which of the following statements about computer virus is false?
ii) It can infect the computer monitor.
c) Which of the following statements is false?
iii) All viruses try to delete your data.
d) Which of these can infect Excel documents?
iii) Macro viruses
e) Which of the following helps to prevent a virus infection?
iv) All of these
f) Which of these is an antivirus software?
iii) Both i and ii
g) Which of these can replicate itself?
ii) Worm
h) Which of the following is available free?
iii) Microsoft Security Essentials
C.T. – 01 Syllabus for Class Seven
Chapter 04 (Computer Virus)
Chapter 05 (QBasic Looping Statement)
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