SEE Science (Virus) Notes

Virus

1)    Write the enzymes or vitamins found in virus.

Ans: The enzymes found in virus are riboflavin and biotin.

2)    What is virology?

Ans: The branch of microbiological science which deals with the study of viruses is called virology.

3)    Write the full form of HIV, AIDS and TMV.

Ans: The full form of

         HIV – Human Immune Deficiency Virus

         AIDS – Acquired Immune Deficiency Syndrome

         TMV – Tobacco Mosaic Virus

         PMV – Potato Mosaic Virus

        TSWV – Tomato Spotted With Virus

4)    Which disease is caused by Rhino virus?

Ans: common cold is caused by Rhino virus.

5)    Write living characters of virus.

Ans: Living characters of virus are:

a)     They can reproduce only inside the living host cell.

b)     They show respond to light, chemicals and heat.

c)     They have their own genetic material in the form of RNA or DNA.

d)     They are infective and capable of spreading diseases.

6)    On the basis of given symptom, write the name of diseases and virus which causes it.

a)     High fever, stiff neck

Ans: Disease – Polio

        Virus – Polio virus

b)     Wet eyes, becomes sensitive to light

Disease – Measles 

Virus – Paramyxo virus

7)    Write specific character of virus.

Ans: Specific characters of virus are:                                 

a)     They can reproduce only inside the living host cell.

b)     They do not respire at all.                        

c)     They show respond to light, chemicals and heat.

d)     They are host specific.

8)    Write the name of virus that causes measles? In which organ of the body does it affect?

Ans: Paramyxo virus cause measles.

                       It affects respiratory tract, mouth, skin and intestine.

9)    'All HIV infected person do not suffer from AIDS' why?

Ans: All HIV is the virus that causes weakness in the body system i.e. attracts the body's immune system. Person with HIV positive will develop AIDS only when the number of specific types of cell in their immune system drops below a certain level or when they develop one of a specific group of opportunistic infections. If such conditions don't appear in immune system, person with HIV virus doesn't suffer from AIDS.

10)  Nose and mouth should be covered with handkerchief while sneezing and coughing when somebody is suffering from common cold. Why?

Ans: Common cold spreads through moisture droplets, released by the infected person during sneezing and coughing through air medium. When a healthy person breathes in such contaminated air, rhino virus enters into the respiratory tract and he/she will suffer from common cold. Therefore, nose and mouth should be covered with handkerchief while sneezing and coughing when somebody is suffering from common cold.

11)  Write any two ways that does not transmit AIDS.

Ans: Ways of controlling AIDS are:

a)    Have sexual relation with only one faithful partner i.e. husband and wife.

b)    By avoiding the use of drugs.

c)    By avoiding the use of contaminated syringes, blades, etc.

d)    By using the condoms or other barrier method of contraception.

12)  Viruses are obligatory parasites, why?

Ans: Viruses are obligatory parasites because they are fully depends on living organisms for multiplication.

13)  Why AIDS is dangerous?

Ans: AIDS weakens the human body's immunity or self-defense mechanism. When the natural immunity or immune system becomes complete weak or functionless, person becomes susceptible to number of diseases. Since, the remedy of this disease has not been developed so far, therefore AIDS is dangerous.

14)  What is bacteriophage virus?

Ans: The virus that attacks bacteria and destroy their nuclear material is called bacteriophage virus.

15)  Why are polio victim often paralysed?

Ans: Polio virus attacks the nervous tissue and motor nerves of the spinal cord which affect the functioning of the voluntary muscles. As a result, polio victim suffers from paralysis. 

16)  Common cold can transmit through kiss and hug but not AIDS, why?

Ans: Rhino virus is found in mucous, saliva or mouth part of the body but retro virus is found in blood, sexual fluid of the infected person not in saliva. Therefore, common cold can transmit through kiss and hug but not AIDS.

17)  In which diseases paralysis, pneumonia and hydrophobia are seen? Mention it.

Ans: Paralysis – Polio

        Pneumonia – AIDS

        Hydrophobia - Rabies

18)  It is difficult to recover from diarrhea from AIDS infected person. Give reason.

Ans: AIDS virus (i.e. HIV) attracts T-lymphocytes (a type of WBC) of human blood and weakens the immune system. Since HIV reduces the acquired immunity of the human body, the patient suffering from AIDS cannot fight against infections and diseases. So, it is difficult to recover from diarrhea from AIDS infected person.

19)  Why rabies is also called hydrophobia?

Ans: Rabies is also called hydrophobia because rabies virus attacks the brain and the spinal cord that make the people to fear of water.

20)  Write the non-living characters of virus.

Ans: The non-living characters of virus are:

a)     They do not respire at all.

b)     They do not perform metabolic activities.

c)     They are a cellular i.e. cytoplasm, nucleus and cell organelles are absent.

d)     The can be crystallized like a chemical substance.

21)  What is a virus?

             Ans: A virus is a sub-microscopic obligatory parasite that causes various                        diseases in plants and animals.

22)  Describe the structure of a bacteriophage virus with a labeled diagram.

       Ans: The body of a bacteriophage virus can be divided into two parts i.e. head and tail. The head is hexagonal in shape which consists of a protein coat called capsid. The capsid surrounds the genetic material i.e. DNA. The cylindrical tail consists of basal plate and tail fibres. The tail fibres are adapted to stick to the surface of host's body.

23)  "Viruses are also called the borderline of the living beings and non-living beings." Justify this statement with reasons.

Ans: Viruses show the properties of both living beings and non-living beings. So viruses are also called the borderline of the living beings and non –living beings.

24)  Write down the average size of viruses.

                 Ans: The size of viruses varies from 25 nanometers to 250 nanometers.

25)  Make a list showing the causative agent and affected organs of the patients suffered from following diseases.

S.N.	Name of the disease/Incubation period	Causative agent	Affected organs parts
1	Common cold (1-3 days)	Rhino virus	Upper part of respiratory tract i.e. nose and throat.
2	Measles (10-14 days)	Paramyxo virus	Mouth, skin, respiratory tract, intestine
3	Mumps (12-26 days)	Paramyxo virus	Respiratory tract, parotid  glands, testes of male, breasts of female, salivary gland
4	Polio (Paralytic: 9-13 days and Non-paralytic: 4-10 days)	Polio virus	Pharynx, blood, intestine, spinal cord, motor nerves.
5	AIDS (12 year)	Retro virus	Blood, skin, brain.
6	Rabies (14 days to many months)	Rabies virus	Spinal cord, brain.

26)  Name the causative agent of rabies. Write down the preventive measures of rabies.

                Ans: The causative agent of rabies is rabies virus. The preventive measures of rabies are as follows:

i) By the administration of anti-rabies vaccine in the bite of rabid animals.

ii) Wound made by the bite of rabid animal should be washed with soap water.

iii) By killing street dogs.

iv) By complete immune immunization of pet dog, cat etc.

v) Resister and license all domestic dogs.

27)  Write down the main methods by which AIDS is transmitted from one person to another.    

Ans: The main methods by which AIDS is transmitted from one person to another person are as follows:

i) By the unsafe sexual intercourse with the infected partner.

ii) By the use of contaminated needles and syringes.

iii) Through the contaminated blood transfusion.

iv) From the infected mother to her unborn or newly born child.

28)  Name the virus transmitted through the unsafe sexual contact. "HIV itself does not kill human beings but it promotes other disease". Justify this statement. 

Ans: The virus which is transmitted by the unsafe sexual intercourse is HIV i.e. Human Immunodeficiency Virus (Retro virus).

                          AIDS is cause by HIV virus which reduces the immunity power of the human body and makes the body prone to many diseases. The person suffering from AIDS actually dies from other infections or diseases because the body is not able to resist the disease causing organisms. Therefore, HIV itself does not kill human beings but it promotes other disease.

29)  Differences between viruses and bacteria.

Viruses	Bacteria
They do not perform metabolic activities.	They perform metabolic activities.
They do not have a cellular structure.	They have a cellular structure.