Introduction to Virus

Viruses are the ultrasonic, nucleoprotein that reproduce only inside the living things. This note contains information about its living and non-living character along with its shape and occurrence.

Summary

Viruses are the ultrasonic, nucleoprotein that reproduce only inside the living things. This note contains information about its living and non-living character along with its shape and occurrence.

Things to Remember

  •  Viruses are the ultrasonic, nucleoprotein that reproduce only inside the living things.
  • All the viruses are minute and simplest organisms which can be observed only by the use of electron microscope.
  • They are metabolically inactive outside the host cell because they do not have enzyme systems and proteins synthesis machinery. Thus, they are obligatory intracellular pathogens or parasite.
  • They are composed of nucleic acid either DNA or RNA or both and protein. The protein that surrounds the nucleic acid is called protein coat, the capsid.
  • Outside the host cell, they can be crystallized and behaves like the chemicals.
  • Viruses are nucleoprotein entities of high molecular weight and have the power of multiplication.

 

MCQs

No MCQs found.

Subjective Questions

Q1:

What is communication?

 


Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: <p>Communication is the means of sending and receiving information between two or more people. It is also the act of conveying intended meaning to the another person through the use of mutually understood signs.</p>

Q2:

Why is communication important?

 


Type: Short Difficulty: Easy

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Answer: <p>Communication is important because it saves time, budget and labour. Information, ideas and opinions can be shared among many persons at any given time through modern means of communication. It is the basic infrastructure in a culture, society, region etc. Communication fosters education, trade and relationships. It also promotes cultural exchange and conflict resolution.</p>

Q3:

What are the different ways in which we communicate?

 


Type: Short Difficulty: Easy

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Answer: <p>The different ways we communicate are as follows:</p>
<ul>
<li>Spoken or Verbal Communication: face-to-face, telephone, radio or television and other media.</li>
<li>Non-Verbal communication: body language, gestures, how we dress or act.</li>
<li>Written Communication: letters, e-mail, books, magazines, the internet or via other media.</li>
<li>Visualizations: graphs and charts, maps, logos and other visualizations can communicate messages.</li>
</ul>

Q4:

How can we say that the world is small?

 


Type: Short Difficulty: Easy

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Answer: <p>By using the means of communication, we can hear and see the activities of the world by sitting in our home. One can pass information, ideas and opinions with the click of one&rsquo;s thumb in just a second. The relatives who are living thousands of miles away can be seen in the device held in one&rsquo;s palm. So, the means of communication have contracted the world and made small.</p>

Q5:

What role does communication play in the development of a country?

 


Type: Short Difficulty: Easy

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Answer: <p>Communication plays an important role in the development process. It reduces the distance and makes the flow of information faster and easily available. It also saves time, budget and labour. Information, ideas and opinions can be shared among many persons at any given time through modern means of communication. It is the basic infrastructure in a culture, society, region etc.</p>

Q6:

What are the different means of communication used in modern time?

 


Type: Very_short Difficulty: Easy

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Answer: <p>The different means in which we communicate in modern time are e- mail, internet, mobile phones, television, fax, magazines, newspapers etc.</p>

Q7:

Can you imagine  your life without communication?

 


Type: Short Difficulty: Easy

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Answer: <p>No, we cannot imagine our life without communication. Communication&nbsp;is a basic infrastructure of the development of a civilization.</p>

Q8:

When did modern means of communication start in our country?


Type: Short Difficulty: Easy

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Answer: <p>Modern means of communication started in our country in 1880 AD.</p>

Q9:

Write any two means of communication.


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>The two means of communication are as follows:</p>
<ul>
<li>Internet</li>
<li>Telephone</li>
</ul>

Q10:

Write any one advantage of communication.


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>One advantage of communication is that it makes the flow of information faster and easily available.</p>
<p>&nbsp;</p>
<p>&nbsp;</p>

Videos

What is Communication?
Barriers in Communication
Verbal communication
Introduction to Virus

Introduction to Virus

Virus:

Viruses are the ultrasonic, nucleoprotein that reproduces only inside the living things.

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source:opentextbc.ca

Characteristics of Viruses:

  • All the viruses are minute and simplest organisms which can be observed only by the use of electron microscope.
  • The diameter of viruses ranges from about 20-30 mm on average. They are 50 times smaller than bacteria.
  • They are metabolically inactive outside the host cell because they do not have enzyme systems and proteins synthesis machinery. Thus, they are obligatory intracellular pathogens or parasite.
  • They are composed of nucleic acid either DNA or RNA or both and protein. The protein that surrounds the nucleic acid is called protein coat, the capsid.
  • Viruses do not have cellular structure i.e. they lack a true nucleus, cytoplasm and cytoplasmic organelles like mitochondria, Golgi complex etc.
  • During reproduction, the virus particle disorganized into molecular constituents inside the host cell. This phase is called eclipse phase.
  • They show respond to chemicals, heat, and temperature.
  • Outside the host cell, they can be crystallized and behaves like the chemicals.
  • They cannot show the independent mode of life.
  • They are highly specific to their host.
  • Viruses cannot reproduce by fission or conjugation.
  • They undergo mutation like living organisms.

Shape:

Viruses occur in three main shapes;

  • Spherical (Cubical or Polyhedral) viruses. Eg; Poliovirus
  • Helical(cylindrical or rod ) viruses. Eg; Tobacco Mosaic virus
  • Complex( tadpole shape) virus. Eg; Bacteriophage

Living characters of viruses

  • Viruses can grow and reproduce within the host cell.
  • The ultrastructure of most viruses shows similar morphological structure to bacteria like cocci.
  • They undergo mutation like living organisms.
  • They have their own genetic material in the form of RNA, DNA or both.
  • They show intracellular parasitism and can be transmitted from the diseased host to healthy ones.
  • They are infective and capable of spreading diseases.
  • They respond to light, chemicals, and temperature.

Non-living character of viruses

  • They lack a complete cellular structure.
  • They lack enzyme system and do not have metabolic activity of their own.
  • Viruses do not respire.
  • Some viruses can be crystallized and stored in bottles like chemicals.
  • They can be precipitated by a number of a chemical substance.
  • They depend upon living host for their existence.
  • They are with high specific gravity.
  • Viruses are nucleoprotein entities of high molecular weight and have the power of multiplication.

Lesson

Virus

Subject

Biology

Grade

Grade 11

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