MCQ on Viruses and Viroids with Answers Pdf

Master MCQ on Viruses and Viroids with Answers Pdf with our targeted MCQ series – perfect for Class 10, 11, and 12 Biology students! These multiple-choice questions simplify complex topics like viral structure, replication, and diseases (COVID-19, TMV) while clarifying key differences between viruses, viroids, and virions.

Aligned with NCERT, CBSE & NEET syllabi, each PDF includes detailed answers with diagrams for visual learning. Download free chapterwise MCQ sets covering lytic/lysogenic cycles, prions, and viral classification. Whether preparing for board exams or NEET, our resources help you tackle assertion-reason questions and diagram-based problems confidently. Access grade-specific PDFs (Class 10: basic concepts; Class 11/12: advanced virology) instantly!

Important Points to Remember about Viruses and Viroids 

1. Virus is an ultra microscopic obligatory parasites which becomes active only inside  a living cell or host cell. 
2. Viruses have either DNA or RNA as the genetic material. Viruses having RNA as the  genetic material are known as retroviruses.
3. Generally all viruses are made up of nucleoproteins (Nucleic acid + Protein). The nucleic  acid may be DNA or RNA as genetic material. In a particular virus either DNA or RNA is the genetic material. Both are never present in a virus. Single stranded RNA or ss RNA – Tobacco mosaic virus (TMV)
4. There is a protective covering of protein called capsid around the infective part. Capsid consists of small subunits called capsomeres and has antigenic property.
5. All the viruses are obligate parasite i.e.  they remain inert outside the host cell. They  have ability to syntheize nucleic acids and  proteins by using host cellular machinery  (ribosomes, tRNAs, aminoacids, energy). 
6. Viroids, the smallest known pathogens,  are naked, circular, single-stranded RNA  molecules that do not encode protein but  autonomously replicate when introduced into host plants. Viroids only infect plants; some cause economically important diseases of crop plants, while others appear to be benign.

MCQ on Viruses and Viroids with Answers Pdf

Check your knowledge by solving MCQ on Viruses with answers Pdf. Below MCQs will help learners for preparing NEET examinations and will be able to score better as all the resources required to study of Viruses and Viroids are provided here. We tried to simplify the complexities of some of the topics in the form of Viruses & Virioids multiple choice questions and answers so that preparation becomes easy for the NEET aspirants.

These MCQs  are also useful for preparing for various competitive exams like KVPY, CET, NTSE, NET, SET. So, we are providing MCQ Questions on Viruses that will help you to understand the basic concepts of viruses and even help you get a good score with sufficient practice questions for each topic.

1. Viroids differ from viruses in having
(1) DNA molecules without protein coat
(2) RNA molecules with protein coat
(3) RNA molecules without protein coat
(4) DNA molecules with protein coat
Answer: 3
Explanation: Viroids are composed of small circular RNA molecules that lack a protein coat, unlike viruses.

2. Which of the following organisms does not have a cellular structure is
(1) fungus
(2) bacteria
(3) Virus
(4) amoeba
Answer: 3
Explanation: Viruses are acellular; they lack a cell membrane or organelles and are not considered living outside a host.

3. Microorganisms that must be observed with an electron microscope are
(1) bacteria
(2) yeast
(3) mushroom
(4) Virus
Answer: 4
Explanation: Viruses are too small to be seen with a light microscope and require an electron microscope.

4. The shell and core of a bacteriophage are
(1) lipids, proteins
(2) Lipids, nucleic acids
(3) protein, nucleic acid
(4) nucleic acid, protein
Answer: 3
Explanation: The protein shell (capsid) encloses nucleic acid (DNA or RNA) in a virus like a bacteriophage.

5. Bacteriophages are viruses that live in cells
(1) plant
(2) animal
(3) bacteria
(4) people
Answer: 3
Explanation: Bacteriophages specifically infect and replicate within bacteria.

6. Which of the following is not a type of virus
(1) animal virus
(2) plant virus
(3) Prion
(4) Bacterial virus
Answer: 3
Explanation: Prions are infectious proteins without nucleic acid, not viruses.

7. Which of the following virus types are the pathogens that can cause “bird flu” to chickens and ducks
(1) Microbial viruses
(2) plant virus
(3) Invertebrate viruses
(4) Vertebrate virus
Answer: 4
Explanation: Bird flu is caused by avian influenza viruses, which are vertebrate viruses.

8. Which of the following statements about viruses, bacteria and fungi is correct
(1) decomposers in the ecosystem
(2) Viruses are made up of cells
(3) Bacteria have a formed nucleus
(4) Fungi can only use readily available organic matter
Answer: 4
Explanation: Fungi are saprophytes and rely on preformed organic substances; bacteria lack a nucleus, and viruses are acellular.

9. Viruses are divided into animal viruses, plant viruses and bacterial viruses, and they are classified in this way on the basis of
(1) According to their different structures
(2) Depending on their host
(3) According to their food
(4) According to their degree of harm to humans
Answer: 2
Explanation: Viruses are classified by the type of host they infect—animals, plants, or bacteria.

10. Which of the following statements is incorrect about viruses
(1) Viruses can’t live on their own
(2) virus camp parasitic life
(3) Viruses have cell walls
(4) Viruses can only be seen with an electron microscope
Answer: 3
Explanation: Viruses lack cell walls; they consist of genetic material and a protein coat only.

11. AIDS is caused by the Human Immunodeficiency Virus (HIV), which of the following statements about the virus is correct
(1) cellular structure
(2) Consists of a protein coat and the genetic material inside
(3) Able to live independently on culture medium
(4) to observe with an optical microscope
Answer: 2
Explanation: HIV has a protein coat and RNA inside; it is observed via electron microscopy and cannot live outside host cells.

12. Which of the following statements is wrong for viroids?
(1) They lack a protein coat
(2) They are smaller than viruses
(3) They cause infections
(4) Their RNA is of high molecular weight
Answer: 4
Explanation: Viroid RNA is low molecular weight, unlike viral genomes.

13. Which of the following shows coiled RNA strand and capsomeres?
(1) Polio virus
(2) Tobacco mosaic virus
(3) Measles virus
(4) Retrovirus
Answer: 2
Explanation: TMV has a helical structure with coiled RNA and capsomeres forming its protein coat.

14. 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
Answer: 1
Explanation: Viruses consist only of nucleic acid (RNA/DNA) and a protective protein coat.

15. The protein coat of viruses that enclose the genetic material is called
(1) Virion
(2) Capsid
(3) Peplomers
(4) Capsomers
Answer: 2
Explanation: The capsid is the protein shell that encloses the viral genome.

16. Viruses have:
(1) DNA enclosed in a protein coat
(2) Prokaryotic nucleus
(3) Single chromosome
(4) Both DNA and RNA
Answer: 1
Explanation: Viruses have either DNA or RNA enclosed in a protein coat, but not both.

17. Satellite RNAs are present in some
(1) Plant viruses
(2) Viroids
(3) Prions
(4) Bacteriophages
Answer: 1
Explanation: Some plant viruses carry satellite RNAs which require a helper virus to replicate.

18. Which statement is wrong for viruses?
(1) All are parasites
(2) All of them have helical symmetry
(3) They have ability to synthesize nucleic acids and proteins
(4) Antibiotics have no effect on them
Answer: 2
Explanation: Not all viruses have helical symmetry; some have icosahedral or complex shapes.

19. Which of the following is the genome of the virus?
(1) DNA
(2) RNA
(3) DNA or RNA
(4) DNA and RNA
Answer: 3
Explanation: Viruses contain either DNA or RNA, but never both.

20. Which of the following is the largest virus?
(1) Megavirus chilensis
(2) Arbo virus
(3) Herpes virus
(4) Mumps virus
Answer: 1
Explanation: Megavirus chilensis is among the largest viruses known, even larger than some bacteria.

21. Virus envelope is known as:
(1) Capsid
(2) Virion
(3) Nucleoprotein
(4) Core
Answer: 1
Explanation: Capsid is the protein coat forming the envelope around the nucleic acid.

22. The causative agent of mad-cow disease is a
(1) Prion
(2) Worm
(3) Bacterium
(4) Virus
Answer: 1
Explanation: Mad-cow disease is caused by a prion, an infectious protein particle.

23. Viruses are no more “alive” than isolated chromosomes because
(1) both require the environment of a cell to replicate
(2) they require both RNA and DNA
(3) they both need food molecules
(4) they both require oxygen for respiration
Answer: 1
Explanation: Like chromosomes, viruses need host cellular machinery to replicate.

24. Which one of the following statements about viruses is correct?
(1) Nucleic acid of viruses is known as capsid
(2) Viruses possess their own metabolic system
(3) All viruses contain both RNA and DNA
(4) Viruses are obligate parasites
Answer: 4
Explanation: Viruses can only reproduce inside a host cell, making them obligate parasites.

25. A type of cell culture that can reproduce for an extended number of generations and is used to support viral replication is a
(1) Primary cell culture
(2) Continuous cell line
(3) Cell strain
(4) Diploid fibroblast cell
Answer: 2
Explanation: Continuous cell lines can be maintained indefinitely and are ideal for growing viruses.

26. Which of the following is not an RNA virus?
(1) Retrovirus
(2) Enterovirus
(3) Rhabdovirus
(4) Adenovirus
Answer: 4
Explanation: Adenoviruses contain double-stranded DNA.

27. Tobacco mosaic virus is a tubular filament of size
(1) 700 × 30 nm
(2) 300 × 10 nm
(3) 300 × 5 nm
(4) 300 × 20 nm
Answer: 4
Explanation: TMV is about 300 nm long and 20 nm wide.

28. Cauliflower mosaic virus contains
(1) ss RNA
(2) ds RNA
(3) ds DNA
(4) ss DNA
Answer: 3
Explanation: Cauliflower mosaic virus has a double-stranded DNA genome.

29. Enzymes are absent in
(1) Cyanobacteria
(2) Viruses
(3) Algae
(4) Fungi
Answer: 2
Explanation: Viruses do not have enzymes for metabolism outside host cells.

30. A virus can be considered a living organism because it
(1) responds to touch stimulus
(2) respires
(3) reproduces (inside the host)
(4) can cause disease
Answer: 3
Explanation: Viruses can reproduce, but only inside living host cells.

31. A strain of virus is made with nucleic acid of TMV (Tobacco mosaic virus) and protein coat of HRV (Holmes rib-grass virus) and then the tobacco leaf is infected
(1) Symptoms of TMV will appear
(2) Symptoms of HRV will appear
(3) Symptoms of both TMV and HRV will appear
(4) Symptoms of none of these will appear
Answer: 1
Explanation: The genetic material determines the symptom, so TMV symptoms will appear.

32. Which one of the following statements about viruses is not correct
(1) Can multiply outside a living cell
(2) Can be cultured in a cell free medium
(3) Have an independent metabolism
(4) Viruses are facultative parasite
Answer: 4
Explanation: Viruses are obligate parasites, not facultative.

33. Which of the following is true for viruses
(1) They invariably contain DNA
(2) They multiply only in host cell
(3) They occur only inside bacteria
(4) Their genetic material is RNA
Answer: 2
Explanation: All viruses require a host cell to multiply.

34. Which of the following method is used for the production of vaccines against yellow fever?
(1) tissue-culture method
(2) chick-embryo method
(3) through susceptible animals
(4) through appropriate media
Answer: 2
Explanation: Yellow fever vaccines are produced using chick-embryo technology.

35. Viruses cannot multiply of their own because they
(1) Do not have sex organs
(2) Lack genetic material
(3) Lack cellular machinery to use its genetic material
(4) None of the above
Answer: 3
Explanation: Viruses cannot perform metabolism or reproduction without a host’s cellular machinery.

36. Which one of the following statements about viruses is correct?
(1) Viruses possess their own metabolic system
(2) Viruses contain either DNA or RNA
(3) Viruses are facultative parasites
(4) Viruses are readily killed by antibiotics
Answer: 2
Explanation: Viruses carry either DNA or RNA, never both, and lack their own metabolism.

37. Influenza virus has
(1) DNA
(2) RNA
(3) both DNA and RNA
(4) only proteins and no nucleic acids
Answer: 2
Explanation: Influenza virus contains RNA as its genetic material.

38. Tobacco Mosaic Virus (TMV) genes are
(1) double stranded RNA
(2) single stranded RNA
(3) polyribonucleotides
(4) proteinaceous
Answer: 2
Explanation: TMV carries a single-stranded RNA genome.

39. Virus was discovered by
(1) D. Ivanowsky
(2) Beijerinck
(3) Stanley
(4) Herelle
Answer: 1
Explanation: Ivanowsky first identified viruses as filterable infectious agents.

40. The Tobacco mosaic virus was crystallized for first time by
(1) W.M. Stanley
(2) Louis Pasteur
(3) Edward Jenner
(4) Andre Lwoff
Answer: 1
Explanation: Stanley crystallized TMV, proving that viruses could be isolated like chemical compounds.

Mcq on viruses and viroids with answers pdf download, Mcq on viruses and viroids with answers pdf class 11, Mcq on viruses and viroids with answers pdf class 10, Virus, multiple choice questions and answers pdf, Mcq on viruses and viroids with answers pdf class, Viruses questions and answers PDF Grade 11, Viruses MCQ with answers