MCQ on Virus

Virus is a small connection of genetic code that is present in the form of RNA and DNA. It is surrounded by a coat of protein known as the capsid. Viruses can't replicate alone; they infect cells and use their components to make copies of themselves. Viruses are submicroscopic which means that they can't be seen under a microscope. They can survive in a living cell only. They are small in size even smaller than bacteria, their size ranges from 20-300 nanometers (nm).

Viruses are classified into different categories of the basics of different categories.

On the basis of the presence of the nucleus

• DNA viruses have DNA as their genetic materials. They can be classified into Single-stranded DNA virus and Double-stranded DNA virus

• RNA Viruses have RNA as their genetic material. These are classified as Single-stranded RNA viruses and Double-stranded RNA viruses.

Read more: Structure of DNA and RNA

On the basis of symmetry, we have Helical symmetry virus (Orthomyxovirus), Complex virus (Poxvirus), Cubical symmetry virus (Reovirus), and Spiral shaped virus (Helical). On the basis of the host range, there are animal viruses and plant viruses.

Ques 1. Viruses require _______________ to grow.

1. Animals
2. Plants
3. living cells
4. bacteria

Ans. c) living cells

Explanation: Viruses require living cells to grow. Viruses can’t survive or replicate on their own because they don’t have the required cellular machinery. So, they can survive only in a living cell. Viruses are not alive they can either grow or move. A virus first infects a cell and then it can multiply.

Ques 2. TMV contains:

1. ds-RNA
2. single-stranded RNA
3. ds-DNA
4. ss-DNA

Ans. b) single-stranded RNA

Explanation: TMV or Tobacco mosaic virus is a single-stranded RNA virus it is made up of nucleic acid i.e. RNA and a surrounding protein coat. This is most commonly found in potatoes and tomatoes plant. TMV can spread through mechanical transmitting i.e. through workers' hands, clothing and tools. There is no chemical cure for TMV. It can only be prevented by purchasing virus-free plants and destroying plants showing symptoms.

Ques 3. Which of the following process is absent in the virus:

1. Mutation
2. Replication
3. Production of energy
4. All

Ans. c) Production of energy

Explanation: Viruses cannot have their energy. They derive their energy from and all other metabolic functions from the host cells. The virus cannot produce energy in the environment but when they enter the host cell they use their energy to survive and replicate.

Ques 4. Mumps is caused by:

1. Bacteria
2. Virus
3. Rhizopus
4. Animals

Ans. b) Virus

Explanation: Mumps is a contagious disease caused by a Virus. The symptoms of Mumps are headache, a few days of fever, tiredness, less appetite also the salivary glands swell up. This disease is particularly seen in children. The average period of mumps is 16 to 18 days. Currently, there is no cure for mumps but the infection should pass within 1 or 2 weeks.

Ques 5. Enzymes are not found in:

1. Fungi
2. Viruses
3. Cyanobacteria
4. Algae

Ans. b) Viruses

Explanation: Viruses are made of nucleic acid (i.e. DNA or RNA) and surrounded by a coat of protein so enzymes are not found in enzymes. Viruses don't have enzymes so they cannot synthesize proteins.

Ques 6. What is the phage that attacks a host cell but does not destroy it:

1. Temperate Phage
2. Sexduction
3. Phycophage
4. Virulent Phage

Ans. a) Temperate Phage

Explanation: A phage that attacks the host cell but doesn't destroy it is called Temperate Phage. It is the type of Bacteriophage. Temperate Phage enters into a lysogenic relationship with its host and doesn't destroy it. Example of such bacteriophage is lambda and Mu etc.

Ques 7. Which of the following characteristic supports the non-living nature of the virus:

1. Absence of RNA
2. Absence of nucleus
3. Abiotic state
4. Ability of reversible crystallization

Ans. d) Ability of reversible crystallization

Explanation: Viruses produce infections through both living and non-living features. Viruses are said to be non-living as they can be crystallized and have no energy metabolism. They don't reproduce independently but replicate by invading living cells.

Ques 8. The term ‘antibiotic’ was proposed by:

1. Flaming
2. Waksman
3. Brien
4. B.M. Duggar

Ans. b) Waksman

Explanation: The term Antibiotic was proposed by Selman Waksman in 1942. He discovered over 20 antibiotics in his lifetime.

Ques 9. A virus is made up of _______.

1. Protein coat and nucleic acid
2. Protein coat and mitochondria
3. Nucleic acid and cell membrane
4. Nucleic acid, cell wall, and cell membrane

Ans. a) Protein coat and nucleic acid

Explanation: Protein coat and nucleic acid. Viruses contain nucleic acid either DNA or RNA and are surrounded by a coat of protein known as a capsid. Viruses are even small than bacteria.

Ques 10. The largest virus is ______.

1. Megavirus chilensis
2. Arbo virus
3. Herpes virus
4. Mumps virus

Ans. a) Megavirus chilensis

Explanation: Megavirus chilensis is the largest virus. It is 1,259,197 in its genome Length and 440 Capsid diameter (nm).

Ques 11. Viruses that attack bacteria are called_______.

1. Virophage
2. Lysophage
3. Bacteriophage
4. None of the above

Ans. c) Bacteriophage

Explanation: A bacteriophage is a virus that infects bacteria. The meaning of the word “bacteriophage” is “bacteria eater”. Bacteriophage is made up of nucleic acid and surrounded by a protein coat. Bacteriophages cannot infect human cells so they pose no harm to human beings. This bacteria can be found in the soil, inside plants, animals, and also deep inside the earth’s crust.

Ques 12. In which unit, the size of viruses is measured in _________?

1. Centimetres
2. Micrometres
3. Nanometers
4. millimetres

Ans. c) Nanometers

Explanation: The amount and arrangement of the proteins and nucleic acid of viruses determine their size and shape and their size is measured in terms of a nanometer. Most viruses vary in diameter from 20 nanometers to 250–400 nm.

Ques 13. Which of the following viruses belong/s to the family caliciviridae?

1. Hepatitis B virus
2. Hepatitis D virus
3. Hepatitis E virus
4. All of these

Ans. c) Hepatitis E virus

Explanation: Hepatitis E is a virus that can affect the liver of a human being. It can cause the liver to swell up. It can be harmful to pregnant women and people with poor immunity. Its symptoms are mild fever, feeling very tired, less hunger, etc.

Ques 14. Mycovirus have:

1. dsDNA
2. ssRNA
3. dsRNA
4. ssDNA

Ans. c) dsRNA

Explanation: Mycovirus have dsRNA or Double-stranded RNA. Mycovirus usually infect fungi and replicate in fungi. An example of Mycovirus is saccharomyces cerevisiae.

Ques 15. Viroids have:

1. ssRNA not enclosed by a protein coat
2. ssRNA enclosed by a protein coat
3. dsDNA not enclosed by a protein coat
4. dsRNA enclosed by a protein coat

Ans. a) ssRNA not enclosed by a protein coat

Explanation: Viroids belong to the group of pathogens. They consist of single-stranded RNA not enclosed by a protein coat. Viroids come under the category of some higher plants but are simpler than any virus. Viroids are extremely small in size i.e. nucleotides. An example of viroids is the Potato spindle tuber viroid and avsunviroidae.

Ques 16. The tungro disease of rice is caused due to:

1. Virus
2. Viroid
3. Prions
4. Mycoplasma

Ans. a) Virus

Explanation: Tungro disease of Rice is caused by Virus. This disease is transmitted by leafhoppers. To prevent the crop from this virus is destroy the infected plants as soon as possible also use resident varieties such as IR36, IR50 etc against the tungro virus disease.

Ques 17. Which part of the plant is not infected by the virus?

1. Leaf
2. Steam
3. Roots
4. Apical meristem

Ans. d) Apical meristem

Explanation: The Shoot apical meristem(SAM) is not infected by the plant virus. The shoot tips up to 10mm are disease-free. The virus doesn’t infect meristem because the virus cannot multiply within meristem cells.

Ques 18. The rabies virus contains:

1. dsDNA
2. ssDNA
3. dsRNA
4. ssRNA

Ans. d) ssRNA

Explanation: Rabies virus contains a single-stranded RNA virus. It is approximately 60nm X 180nm in measurement. Rabies is caused by a lyssavirus, it affects the saliva and nervous system. Rabies is mostly found in wild animals. Rabies transmission occurs through the saliva of animals.

Ques 19. Which of the following has a complex symmetry?

1. Influenza virus
2. Adenovirus
3. T4 phage
4. All of the above

Ans. c) T4 phage

Explanation: The T4phage virus has a complex symmetry. It is a species of Bacteriophage. T4 phage caused anE. Coli infection. T4 phage exhibit non-living cell traits. It is double-stranded DNA.

Ques 20. The viral genome inserted into the bacterial DNA is termed as_______.

1. Lysogeny
2. Prophage
3. Lytic cycle
4. Virulent phage

Ans. b) Prophage

Explanation: Prophage is a Bacteriophage, it is not harmful to its host. It is a viral genome inserted into the bacterial DNA. Prophage increases the virulence potential of bacterial strains and also increase their ability to survive in harsh environment.