A Detailed Understandings of Viruses Types Classifications and Diseases

 A Detailed Understandings of Viruses Types Classifications and Diseases

A Detailed Understandings of Viruses Types Classifications and Diseases



HOMOLOGY: Study of structures that are similar because of their common origin, but may differ functionally.

BIOCHEMISTRY: Study of chemicals found in living organisms.

CYTOLOGY: Study of the cell.

NOMENCLATURE: The scheme of naming living organisms is called nomenclature. Nowadays, a 2-word naming system is acceptable.

VIRUS is Simplest and smallest non-living particle which measures 17-450 microns. Virus means poison.


A virus is said obligatory parasite because it always needs a living cell (host) to live in.


A Russian scientist who first discovered the virus


An American Scientist who isolated Tobacco Mosaic Virus commonly called TMV

ELECTRON MICROSCOPE                       

A most modern type of microscope, which can magnify up to 10000000 times. It was invented in 1935 in the USA


A protein found in the head of the virus


It refers to the virus                 


A virus is said Bacteriophage when it goes in bacteria for multiplication

LYTIC CYCLE                                    

A type of life cycle in which the virus destroys bacteria after multiplying in it. This is also called Master-Slave Relationship

LYSOGENIC CYCLE                        

Another type of life cycle is in which a virus cooperates with bacteria in sending its genetic material to other bacteria. This is called Host-Guest Relationship

TOBACCO MOSAIC DISEASE:  A viral disease of the tobacco plant in which leaves become molted and white patches appear on the leaf surface.

GENOME: The sum of total genes in an organism is called the genome.

CAPSOMERES: Subunits that combine to make capsid protein in the virus are called capsomeres. In a virus, there are 5 different types of proteins. E.g. Virus of Hepatitis B has 2 proteins in its head.

VIRAL ENVELOPE:  An accessory structure of the virus that protects. Some viruses have it and some don’t have. Those who don’t have are called un-enveloped.

MINUS STRAND RNA VIRUS:  A group of viruses in which RNA works like mRNA and takes messages of RNA for cells.

VIROID: A type of virus that has no capsid protein.

TEMPERATE VIRUS: A type of virus that is capable to do the lytic and lysogenic cycles.

PROPHAGE: A small portion of viral DNA is inserted into bacterial DNA to make recombinant DNA. Prophage mostly remains inactive and is multiplied by bacteria. After some, time prophage is converted into a full phage.

POLIOMYELITIS:  A kind of viral disease caused by Poliovirus.

COLDS: It is a viral infection caused by Rhinovirus. The virus is un-enveloped plus-stranded RNA. There are 200 forms of this virus.

INFLUENZA: Influenza is caused by a virus that attacks mainly the upper respiratory tract – the nose, throat, and bronchi and rarely also the lungs. The infection usually lasts for about a week. It is characterized by sudden onset of high fever, myalgia, headache, severe malaise, cough, and sore throat.

AIDS: Acquired Immunity Deficiency Syndrome. It is a viral infection caused by a retrovirus. The virus attacks immune cells and destroys the defensive system of the body. 

RABIES: A highly dangerous viral infection that basically infects animals of the canine families such as dogs. The virus has been found in the urine of bats also. Human beings become infected when, a rabies-infected dog, bites and its saliva enters into a human body. The cause of rabies is Rhabdovirus.

HORIZONTAL DISTRIBUTION: When plants get a viral infection from their surroundings, it is called horizontal transmission.

VERTICAL TRANSMISSION: When a plant inherits viral infections from previous plant generations, it is called vertical transmission.

HIV: A kind of virus fully known as the human immune virus, which is the cause of aids.

CAPOSI’S SARCOMA:  A condition in which skin becomes disfigured due to AIDS.

DEMENTIA:  A condition in which an AIDS patient loses its memory.

SEPTICEMIA: A condition in which blood becomes poisonous. This is one of the signs of AIDS.

HEPATITIS: Inflammation of the liver, due to virus, toxic agents in drugs.

HEPATITIS A:  A form of hepatitis caused by the Non-enveloped RNA virus. This infection spreads through feces (stool).

HEPATITIS B:  A form of hepatitis caused by an un-usual DNA virus that has 2 proteins in the head and 359 nucleotides of DNA. The infection is found in 200 million people.

HEPATITIS C: Third form of hepatitis caused by the virus. The infection spreads through the blood of an infected person to a healthy person.

YELLOW FEVER: Yellow fever is a mosquito-borne viral disease. The disease occurs in tropical and subtropical areas. A mosquito called (Aedes aegypti), is responsible for transmitting the virus. The symptoms may be fever, headache, vomiting, and backache. As the disease progresses, the pulse slows and weakens, and bleeding of the gums and bloody urine occurs. Jaundice may also occur.

+STRAND RNA VIRUS: A virus whose genetic information consists of a single strand of RNA which encodes messenger RNA and protein. Examples of positive-strand RNA viruses include poliovirus

-STRAND RNA VIRUS: A virus whose genetic information consists of a single strand of RNA which does not encode with messenger RNA. Examples of negative-strand RNA viruses include influenza virus, measles viruses, and rabies virus.

TEST # 01

1.           Virus may consist of the viral genome, Capsid envelop and --------

(a) Tail fiber                         (b) Head                    (c) Both                     (d) None

2.           The smallest virus have only four genes and the largest have several hundred

(a) True                     (b) False

3.           The protein coat that encloses the viral genome is called

(a) Propein               (b) Capsid                 (c) Lapsid                  (d) None

4.           The viral envelop help the virus to infect their host

(a) True                     (b) False

5.           Viruses are generally classified on the basis of morphology and nucleic acids they contain

(a) True                     (b) False

6.           Virus that infects a bacterium is called

(a) Bacteria              (b) Bacterium          (c) Phage                  (d) Bacteriophage

7.           One of the following viruses causes colds in human

(a) Poliovirus           (b) Rhinovirus         (c) Arbovirus          (d) None

8.           More than 200 viruses that cause colds have been identified

(a) True                     (b) False

9.           One of the following is the virus of HIV and was discovered in 1985       

(a)Retroviruses       (b) Poliovirus           (c) Rhinovirus          (d) Arbovirus

10.      In one of the diseases body’s lymphatic cells T4 immune system is impaired

(a) AIDS                     (b) Hepatitis             (c) Poliomyelitis      (d) None

11.      In 90% of cases of HIV the transmission is caused by sexual contact

(a) True                     (b) False

12. AIDS was first associated with homosexual communities in American cities

(a) True                     (b) False

13.      HIV can directly infect brain cells in more than --------–percent  cases

(a) 30                                     (b) 40                         (c) 50                                     (d) 60

14.      Azdothymidine or zidovudine is the best know drug that slows the progression of the disease

(a) True                     (b) False

15.      Viruses reproduce by:
(a) Attacking a host cell and then waiting for the cell to die.

(b) Splitting in half once they enter a host cell and later grow.

(c) Using the process of meiosis.

(d) Using the host cell's DNA to create new viruses.

16.      A virus is unique in that it:
(a) Contains DNA                                        (b) Contains RNA.  

(c) Reproduces in a short time.              (d) cannot reproduce outside a living cell.

17.      Viruses are exceptions to the cell theory, but they have some characteristics of living things. What is one of these characteristics?
(a) They are made up of many specialized cells.
(b) They contain genetic material.

(c) They reproduce by mitosis.

(d) they contain chlorophyll.

18.      A virus that attacks a bacterial cell is called a:
(a) Provirus                                                  (b) Bacteriophage

         (c) Bacilullus                                                 (d) Spirillum

19.      Which type of viral infection literally takes over and quickly destroys the host cell?
(a) Lytic cycle                                               (b) Lysogenic cycle            

(c) Antibiotic cycle                                                 (d) Conjugation cycle

20.      Viruses can cause diseases in which of the following organisms?
(a) Humans              (b) Plants                  (c) Animals               (d) All of the above

21.      Which statement is NOT true of a virus?
(a) It is a non-cellular particle                 (b) It has a nucleic acid core

(c) It has capsid protein as a coat              (d) All are correct

22.      One of the following diseases refers to the inflammation of the liver

         (a) Gastrointitis       (b) Hepatitis             (c) AIDS                     (d) None

23.      One of the following is transmitted by contact with feces from an infected individual

(a) Hepatitis-A         (b) Hepatitis-B         (c) Hepatitis C          (d) All

24.      One of the following is caused by an unusual DNA virus

(a) Hepatitis-A         (b) Hepatitis-B         (c) Hepatitis C          (d) All

25.      One of the following passes through blood from mother to child during pregnancy   and afterward by sexual contact

(a) Hepatitis-A         (b) Hepatitis-B         (c) Hepatitis C          (d) All



1.                 Organs that have a similar morphological appearance but are different anatomically are

            (a) Homology                                              (b) Theology

            (c) Hierology                                                (d) None

2.                 Flippers of whale, wings of bat and arms of man look different, but have the same origin

            (a) True                                                         (b) False

3.                 Organisms that have the same chromosome number and can inter-breed are known as

            (a) Genus                                                      (b) Family

            (c) Species                                                    (d) None

4.                 While classifying organisms, ----is used as the last unit of classification

            (a) Genus                                                      (b) Family

            (c) Species                                                    (d) None

5.                 In the system of classification, Phylum is replaced within plants.

            (a) Division                                                   (b) Kingdom

            (c) Group                                                      (d) None

6.                 The zoological name for house fly is

            (a) Drosophila melanogaster                  (b) Homio sapiens

            (c) Musca domestica                                 (d) None

7.                 The modern system of naming the species is known as Nomenclature

            (a) True                                                         (b) False

8.                 While writing the name of any species first part is taken from the genus and the last part from species and they are written in the Italic form

            (a) True                                                         (b) False

9.                 The word virus in past was used for

            (a) Disease                                                    (b) Pathogen

            (c) Poison                                                     (d) None

10.            Tobacco Mosaic Disease is caused by a virus, and in it, the leaves turn wrinkle and become mottled.

            (a) True                                                         (b) False

11.            Iwanowsky in -----discovered that a virus could be transmitted from an infected organism to a healthy organism of same kind

            (a) 1892                                                        (b) 1893

            (c) 1894                                                        (d) 1895


12.            The magnification of electron microscope is

            (a) 1000000                                                            (b) 100000

            (c) 10000000                                              (d) None

13.            Virus is non-cellular parasite entities. They can not live and reproduce outside of living cells

            (a) True                                                         (b) False

14.            The size of virus range from------------to----------nm

            (a) 18-250                                                    (b) 20-250

            (c) Both                                                         (d) None

15.            The zoological name of the human being is Homo sapiens, where Homo comes from 

            (a) Phylum                                                   (b) Order

            (c) Genus                                                      (d) Species

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