KNOWLEDGE HUB
CLASS 7 COMPUTER SCIENCE
CHAPTER 3 (COMPUTER VIRUS)
EXTRA QUESTIONS
( Read Chapter 3 and complete the HOMEWORK given in Q.2)
1. ANSWER THE FOLLOWING
a. What is the use of Boot record?
Ans: Boot records are programs that the computer uses to start itself up.
b. What do you mean by macro?
Ans: A macro is a set of commands written by the user to be executed later.
c. Which was the first known cell phone virus? When did it appear? Ans:
Commwarrior-A was the first known cell phone virus. It appeared in March 2005.
d. What is the reason behind the rapid spreading of Macro viruses? Ans: Macro
viruses spread rapidly because the infected documents are shared by many users.
e. What do you mean by an executable file?
Ans: An executable file is a file with a .exe. extension
f. Why are Program files attractive targets for computer virus? Ans: Program files
are attractive targets for computer viruses because they are widely used and have
relatively simple formats to which viruses can attach themselves.
g. What are the two things that a computer virus cannot do? Ans: The two things
that a computer virus cannot do are:
• It cannot infect files on write-protected discs such as CDROMS.
• It cannot infect computer hardware such as monitors and keyboards.
h. What is the difference between a computer worm and a computer virus?
Ans: The difference between a compute worm and a computer virus are:
COMPUTER WORM COMPUTER VIRUS
Computer worms spread without Computer Virus spreads only
any human action. It emails copies when the user does something like
of itself to other computers and running an infected program or
infects them attaching an infected file.
i. When does a computer virus become active?
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Ans: A computer virus can become active when we start an infected application or
when we start our computer from a disk that has infected system files.
j. Name the different categories of computer viruses based on their infection
target?
Ans: The different categories of computer viruses based on their infection targets
are:
• Program viruses
• Boot viruses
• Macro viruses
k. Write a short note on Melissa Virus.
Ans: Melissa Virus was released on 26th March 1999 and was designed to infect
macros in documents used by MS Word 97 and 2000. It propagated by e-mailing
itself to the first fifty addresses in the address book of MS Outlook.
l. What does the term Malware include?
Ans: Malware is a general term which includes computer viruses, worms, Trojan
Horse, spyware and spam.
m. What are the different ways in which computer viruses behave? Ans: Different
computer viruses behave in different ways. Some stay active in the morning until
the computer is shut down while some others stay active only as long as the
infected application is running
n. Identify the type of virus from the examples given below:
• Danish boot: Boot Virus
• Nuclear: Macro Virus
• Sunday: Program Virus
• Michelangelo: Boot Virus
• Melissa: Macro Virus
• Acid rain: Program Virus
• Concept: Macro Virus
2. FILL IN THE BLANKS (HOMEWORK)
a. Most viruses stay ___ in the memory until you turn off the computer.
b. Some virus checks the _____ clock and creates havoc when the set time or date
arrives.
c. Malware stands for _______
d. Computer worms usually do not cause _______ damage to programs and files.
e. Macro Viruses spread rapidly as users share ______ documents.
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