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Q59 (IAS/2016) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Microbiology and immunity Official Key

Which of the following statements is/are correct? Viruses can infect 1. bacteria 2. fungi 3. plants Select the correct answer using the code given below.

Result
Your answer: —  ·  Correct: D
Explanation

The correct answer is option D because all three statements are correct.

Viruses may infect plants, animals, or bacterial cells and may cause a disease.[2] This confirms that viruses can infect both bacteria (statement 1) and plants (statement 3).

For fungi, viruses that infect fungi are called mycoviruses.[3] Additionally, chrysoviridae infect fungi, and they also infect plants and possibly insects,[4] and the genus Gammapartitivirus only infects fungi.[5] This confirms statement 2.

Viruses are different from other microorganisms since they reproduce only inside the host organism.[6] This characteristic allows them to infect various types of living cells, including bacteria, fungi, and plants. Therefore, all three statements are correct, making option D the right answer.

Sources
  1. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Ever heard of ... > p. 17
  2. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Ever heard of ... > p. 17
  3. [3] https://microbiologysociety.org/blog/keeping-up-with-virus-taxonomy-viruses-that-infect-fungi.html
  4. [4] https://microbiologysociety.org/blog/keeping-up-with-virus-taxonomy-viruses-that-infect-fungi.html
  5. [5] https://microbiologysociety.org/blog/keeping-up-with-virus-taxonomy-viruses-that-infect-fungi.html
  6. [6] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Snapshots > p. 24
How others answered
Each bar shows the % of students who chose that option. Green bar = correct answer, blue outline = your choice.
Community Performance
Out of everyone who attempted this question.
67%
got it right
PROVENANCE & STUDY PATTERN
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Don’t just practise – reverse-engineer the question. This panel shows where this PYQ came from (books / web), how the examiner broke it into hidden statements, and which nearby micro-concepts you were supposed to learn from it. Treat it like an autopsy of the question: what might have triggered it, which exact lines in the book matter, and what linked ideas you should carry forward to future questions.
Q. Which of the following statements is/are correct? Viruses can infect 1. bacteria 2. fungi 3. plants Select the correct answer using …
At a glance
Origin: Books + Current Affairs Fairness: Moderate fairness Books / CA: 6.7/10 · 3.3/10

This is a classic 'NCERT-plus-Logic' question. While NCERT Class VIII explicitly lists bacteria and plants as hosts, the fungi option requires you to apply the definition of a virus (obligate parasite needing a host cell) to the fact that fungi are cellular organisms. Don't hunt for obscure journals; trust the basic definitions.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
Are there viruses that infect bacteria (bacteriophages)?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Ever heard of ... > p. 17
Presence: 5/5
“Viruses are microscopic and acellular. Viruses multiply when they enter a living cell. They may infect plants, animals, or bacterial cells and may cause a disease.”
Why this source?
  • Explicitly states viruses may infect plants, animals, or bacterial cells.
  • Links viral multiplication to entry into a living cell, implying bacteriophage activity when the host is bacterial.
Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Snapshots > p. 24
Presence: 4/5
“Plant, fungal, and bacterial cells have an extra covering, called a cell wall, around the cell membrane. Bacteria lack a well-defined nucleus.• Cells differ in shape and size. Their shape is related to the function performed by them.• Bacteria, fungi, and protozoa are different kinds of microorganisms.• Viruses are also small in size, but they are different from other microorganisms since they reproduce only inside the host organism.”
Why this source?
  • Notes that viruses reproduce only inside a host organism, supporting the mechanism by which they infect cells.
  • Places viruses in context with bacterial cells in the same section (cell types), reinforcing host–virus interaction concepts.
Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > p. 79
Presence: 3/5
“In fact, viruses do not show any molecular movement in them (until they infect some cell), and that is partly why there is a controversy about whether they are truly alive or not. Why are molecular movements needed for life? We have seen in earlier classes that living organisms are well-organised structures; they can have tissues, tissues have cells, cells have smaller components in them, and so on. Because of the effects of the environment, this organised, ordered nature of living structures is very likely to keep breaking down over time. If order breaks down, the organism will no longer be alive.”
Why this source?
  • States viruses remain inactive until they infect some cell, consistent with how bacteriophages act upon bacteria.
  • Supports the obligate intracellular nature of viruses, a key property of bacteriophages.
Statement 2
Are there viruses that infect fungi (mycoviruses)?
Origin: Web / Current Affairs Fairness: CA heavy Web-answerable

Web source
Presence: 5/5
"This month we are looking at families of viruses that infect fungi – mycoviruses."
Why this source?
  • Explicitly frames the article as covering 'viruses that infect fungi' and uses the term 'mycoviruses'.
  • Indicates that virus families exist which infect fungal hosts.
Web source
Presence: 5/5
"Not only do chrysoviridae infect fungi, they also infect plants and possibly insects."
Why this source?
  • Names a specific virus family (Chrysoviridae) that infects fungi.
  • Describes effects on fungal hosts and host range including fungi.
Web source
Presence: 5/5
"The partitviridae family infect both plants and fungi and each genus of the family has characteristic hosts. The genus Gammapartitivirus only infects fungi"
Why this source?
  • Describes Partitiviridae as infecting both plants and fungi and discusses fungal transmission modes.
  • Identifies a genus (Gammapartitivirus) that only infects fungi.

Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Ever heard of ... > p. 17
Strength: 4/5
“Viruses are microscopic and acellular. Viruses multiply when they enter a living cell. They may infect plants, animals, or bacterial cells and may cause a disease.”
Why relevant

Defines viruses as entities that multiply when they enter a living cell and lists typical host types (plants, animals, bacterial cells).

How to extend

A student could note the general rule 'viruses need living cells to multiply' and ask whether fungi are also living cells that could serve as hosts, then check fungal cell biology or specialized literature for examples.

Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Snapshots > p. 24
Strength: 5/5
“Plant, fungal, and bacterial cells have an extra covering, called a cell wall, around the cell membrane. Bacteria lack a well-defined nucleus.• Cells differ in shape and size. Their shape is related to the function performed by them.• Bacteria, fungi, and protozoa are different kinds of microorganisms.• Viruses are also small in size, but they are different from other microorganisms since they reproduce only inside the host organism.”
Why relevant

States that plant, fungal, and bacterial cells are distinct cell types and reiterates that viruses reproduce only inside a host organism.

How to extend

Combine the fact that fungi are a recognized cell type with the rule that viruses require host cells to infer fungi are plausible viral hosts and then look for specific virus–fungus interactions.

Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > 2.5 Why Is Cell Considered to Be a Basic Unit of Life? > p. 23
Strength: 4/5
“Other microbes, like algae and fungi, are made up of one or more cells. For example, yeast is a unicellular fungus while mould is a multicellular fungus.”
Why relevant

Explains fungi are made of one or more cells (gives yeast as unicellular example).

How to extend

Use the specific fact that some fungi are unicellular (like yeast) to reason that cellular-level viral infection mechanisms applicable to other unicellular hosts might also apply to such fungi, suggesting targeted tests (e.g., microscopy, nucleic acid detection).

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 9: Indian Biodiversity Diverse Landscape > 2. Fungi: > p. 156
Strength: 3/5
“Non-green, non-differentiated plants characterised by total absence of chlorophyll are called Fungi. They grow either on dead, rotten organic matters as saprophytes or live as parasites on other living bodies, which are referred to as hosts. Moulds and mushrooms are the familiar examples of saprophytic fungi. The maximum diversity of fungi is in the Western Ghats, followed by the eastern Himalaya and the western Himalaya.”
Why relevant

Describes fungi as organisms that can live as parasites on hosts and occupy ecological niches where interactions with other microbes occur.

How to extend

Use the idea that fungi interact closely with other organisms (including as parasites) to motivate searching for viruses adapted to those ecological niches or for reports of viral effects on fungal health.

Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > 2.4 How Are We Connected to Microbes? > p. 18
Strength: 2/5
“Can we find microorganisms in other places, too? Let us have a discussion: Have you ever seen a lemon, tomato, orange, or any other food item rot after being left outside for some time? If yes, you may have noticed a powdery or cotton-like growth on them (Fig. 2.9). This happens because they have been infected by microbes. But where did these microbes come from? How did they come in contact with the food? This happens because microorganisms can be found everywhere, be it in water, soil, air, or even in some food items. But why do microorganisms not infect the pickles and murabbas?”
Why relevant

Notes microorganisms (including those that cause visible spoilage) are ubiquitous and infect foods, implying frequent microbe–microbe and microbe–host encounters.

How to extend

A student could extend ubiquity of microbes to hypothesize opportunities for viruses to encounter and evolve to infect fungi on food substrates, then look for empirical records from food microbiology or mycology.

Statement 3
Are there viruses that infect plants (plant viruses)?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Ever heard of ... > p. 17
Presence: 5/5
“Viruses are microscopic and acellular. Viruses multiply when they enter a living cell. They may infect plants, animals, or bacterial cells and may cause a disease.”
Why this source?
  • Explicitly states viruses 'may infect plants, animals, or bacterial cells', directly affirming plant infection.
  • Notes viruses multiply when they enter a living cell, implying they can replicate within plant cells and cause disease.
Indian Economy, Vivek Singh (7th ed. 2023-24) > Chapter 11: Agriculture - Part II > 11.8 Genetically Modified (GM) Crops > p. 342
Presence: 4/5
“GM crops are plants whose DNA (a molecule that encodes the Genetic Information) has been modified using Genetic Engineering. The following are some benefits of GM crops: • More nutritional value• Resistance to bacteria, virus and other components that can damage the plant• Longer shelf life• Less costly GM foods and higher yields The Genetic Engineering Appraisal Committee (GEAC) is the apex body for regulating GM crops, in the Ministry of Environment and Forest under the Environment Protections Act 1986. At present, the government allows commercial production of only one GM crop which is BT cotton and is allowed since 2002.”
Why this source?
  • Describes GM crops engineered for 'resistance to bacteria, virus and other components that can damage the plant', implying viruses do damage plants.
  • Connects plant viral infection to agricultural importance and crop protection measures.
Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Snapshots > p. 24
Presence: 3/5
“Plant, fungal, and bacterial cells have an extra covering, called a cell wall, around the cell membrane. Bacteria lack a well-defined nucleus.• Cells differ in shape and size. Their shape is related to the function performed by them.• Bacteria, fungi, and protozoa are different kinds of microorganisms.• Viruses are also small in size, but they are different from other microorganisms since they reproduce only inside the host organism.”
Why this source?
  • States viruses 'reproduce only inside the host organism', supporting the concept that viruses must infect living host cells (including plant cells) to replicate.
  • Distinguishes viruses from other microbes, reinforcing their mode of infection relevant to plants.
Pattern takeaway: UPSC Science questions often use the word 'can'. In the biological world, if a mechanism (viral infection) exists for one cell type, it likely exists for others unless there is a fundamental biological barrier. The pattern is: Basic Principle (Viruses need cells) + Application (Do fungi have cells?) = Answer.
How you should have studied
  1. [THE VERDICT]: Sitter (Hidden in plain sight). Source: NCERT Class VIII Science, Chapter 2, Page 17 explicitly mentions 'plants, animals, or bacterial cells'.
  2. [THE CONCEPTUAL TRIGGER]: Biological Classification & The Nature of Viruses. The core concept is that viruses are 'obligate intracellular parasites'—they hijack cellular machinery.
  3. [THE HORIZONTAL EXPANSION]: Memorize the hierarchy of non-cellular agents: 1. Bacteriophages (Viruses infecting bacteria). 2. Mycoviruses (Viruses infecting fungi). 3. Viroids (Free RNA, infect plants, e.g., Potato Spindle Tuber). 4. Prions (Misfolded proteins, infect animals, e.g., Mad Cow Disease). 5. Cyanophages (Infect cyanobacteria).
  4. [THE STRATEGIC METACOGNITION]: When reading Science NCERTs, if a text says 'viruses infect plants and animals', ask yourself: 'What about the other kingdoms (Fungi, Protista, Monera)?' The exam tests the universality of biological mechanisms, not just the examples listed.
Concept hooks from this question
📌 Adjacent topic to master
S1
👉 Host range of viruses (plants, animals, bacteria)
💡 The insight

The evidence explicitly lists viruses infecting plants, animals, and bacterial cells, directly addressing bacteriophages.

High-yield for biology and public-health questions: helps distinguish types of pathogens and their targets. Connects to epidemiology, disease control, and biotechnology (phage therapy). Learn by comparing host categories and examples from textbook references.

📚 Reading List :
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Ever heard of ... > p. 17
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 3: Health: The Ultimate Treasure > 3.4 Diseases: What Are the Causes and Types? > p. 32
🔗 Anchor: "Are there viruses that infect bacteria (bacteriophages)?"
📌 Adjacent topic to master
S1
👉 Obligate intracellular replication of viruses
💡 The insight

References state viruses reproduce only inside host cells and remain inactive until infection, a core feature enabling viral infection of bacteria.

Fundamental concept frequently tested in life-science questions and in reasoning about treatments and diagnostics. Links to debates on 'are viruses alive', vaccine strategies, and microbiology lab techniques. Revise definitions, mechanisms of replication, and implications for therapy.

📚 Reading List :
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Snapshots > p. 24
  • Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > p. 79
🔗 Anchor: "Are there viruses that infect bacteria (bacteriophages)?"
📌 Adjacent topic to master
S1
👉 Difference between bacterial and viral infections (treatment implications)
💡 The insight

Evidence notes antibiotics act on bacteria but not viruses, highlighting why recognizing a virus that infects bacteria (phage) is a distinct concept.

Important for questions on public health policy, antimicrobial stewardship, and clinical management. Helps answer prompts on treatment, diagnostics, and alternative therapeutics (e.g., phage therapy). Practice by contrasting pathogen types and appropriate interventions.

📚 Reading List :
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 3: Health: The Ultimate Treasure > 3.5.1 Treatment of diseases > p. 39
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 3: Health: The Ultimate Treasure > 3.4 Diseases: What Are the Causes and Types? > p. 32
🔗 Anchor: "Are there viruses that infect bacteria (bacteriophages)?"
📌 Adjacent topic to master
S2
👉 Virus host range (plants, animals, bacteria)
💡 The insight

The question asks whether fungi can be virus hosts; references list organisms that viruses infect (plants, animals, bacterial cells), so understanding documented host ranges is directly relevant.

High-yield for biology/IAS prelims: knowing which broad organism groups viruses are known to infect helps evaluate novel claims (e.g., fungal infection). Connects to questions on pathogens, host–pathogen interactions, and disease ecology. Prepare by reviewing textbook lists of pathogen hosts and comparing patterns across groups.

📚 Reading List :
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Ever heard of ... > p. 17
🔗 Anchor: "Are there viruses that infect fungi (mycoviruses)?"
📌 Adjacent topic to master
S2
👉 Viruses reproduce only inside host cells
💡 The insight

Understanding that viruses must enter living cells to multiply clarifies the conceptual basis for asking which kingdoms (including fungi) can serve as hosts.

Core concept repeatedly tested: explains why host specificity matters and underpins questions on viral life cycles, pathogenicity, and control measures. Study by linking lifecycle steps to examples across hosts (plants, animals, bacteria) using NCERT-level descriptions.

📚 Reading List :
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Ever heard of ... > p. 17
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Snapshots > p. 24
  • Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > p. 79
🔗 Anchor: "Are there viruses that infect fungi (mycoviruses)?"
📌 Adjacent topic to master
S2
👉 Fungal biology: cell wall, unicellular vs multicellular, ecological roles
💡 The insight

Knowing fungal cell structure and lifestyles (unicellular yeast vs multicellular moulds; cell walls; saprophytes vs parasites) helps assess plausibility of fungi serving as viral hosts and how infections might manifest or be transmitted.

Useful across ecology, biodiversity and disease topics in UPSC: links organismal structure to interactions (parasitism, saprophytism) and disease ecology. Master via NCERT chapters on fungi, focusing on traits that influence susceptibility to pathogens.

📚 Reading List :
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Snapshots > p. 24
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > 2.5 Why Is Cell Considered to Be a Basic Unit of Life? > p. 23
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 9: Indian Biodiversity Diverse Landscape > 2. Fungi: > p. 156
🔗 Anchor: "Are there viruses that infect fungi (mycoviruses)?"
📌 Adjacent topic to master
S3
👉 Host range of viruses (plants, animals, bacteria)
💡 The insight

Reference [1] explicitly lists plants, animals and bacteria as targets of viruses, so understanding viral host range directly answers whether plant viruses exist.

High-yield foundational concept for biology and environment syllabus — explains which organisms viruses can infect and underpins questions on disease ecology and cross-sector impacts (human, animal, crop). Master by comparing host categories and examples; useful for questions linking health, agriculture and microbiology.

📚 Reading List :
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > Ever heard of ... > p. 17
🔗 Anchor: "Are there viruses that infect plants (plant viruses)?"
🌑 The Hidden Trap

Since viruses are covered, look at 'Viroids' and 'Prions' (NCERT Class XI Biology). Viroids differ from viruses as they lack a protein coat and have low molecular weight RNA. Prions cause CJD in humans. Expect a comparison question: 'Difference between Virus and Viroid'.

⚡ Elimination Cheat Code

The 'Science Possibility' Heuristic: In Science & Tech, statements phrased as 'X *can* do Y' or 'X *can* infect Y' are overwhelmingly likely to be Correct (Option D). Proving a negative (that viruses *cannot* infect fungi anywhere in the universe) is scientifically nearly impossible. Unless the statement violates a law of physics (e.g., 'Viruses generate energy without a host'), mark it correct.

🔗 Mains Connection

Link 'Bacteriophages' (Statement 1) to GS-3 Science & Tech (Antimicrobial Resistance). Phage Therapy is an emerging alternative to antibiotics for treating superbug infections. This connects a Prelims biology fact to a Mains public health solution.

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Consider the following statements : I. No virus can survive in ocean waters. II. No virus can infect bacteria. III. No virus can change the cellular transcriptional activity in host cells. How many of the statements given above are correct?

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Which of the following statements is/are correct regarding vegetative propagation of plants? 1. Vegetative propagation produces clonal population. 2. Vegetative propagation helps in eliminating the virus. 3. Vegetative propagation can be practiced most of the year. Select the correct answer using the code given below.

IAS · 2013 · Q78 Relevance score: 2.06

With reference to the food chains in ecosystems, which of the following kinds of organism is/are known as decomposer organism / organisms? 1. Virus 2. Fungi 3. Bacteria Select the correct answer using the codes given below.