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Chapter 1: The Living World
Biodiversity; Need for classification; three domains of life; taxonomy and systematics; concept of species and taxonomical hierarchy; binomial nomenclature.
17
Chapter 2: Biological Classification
Five kingdom classifications; Salient features and classification of Monera, Protista and Fungi; Lichens, Viruses and Viroids.
28
Chapter 3: Plant Kingdom
Classification into major groups; Features and examples of Algae, Bryophyta, Pteridophyta, Gymnospermae (Excluded: Angiosperms, Plant Life Cycle & Alternation of Generations).
24
Chapter 4: Animal Kingdom
Salient features and classification: Non-chordates up to phyla level and chordates up to class level; examples of each. (No live specimens to be displayed).
34
Chapter 5: Morphology of Flowering Plants
Morphology of root, stem, leaf, inflorescence, flower, fruit, seed; description of family Solanaceae.
46

Viroids: Structure and Characteristics

Viroids: Structure and Characteristics — CBSE Class 11 Biology 30 MCQ Quiz

Unit 1: Diversity of Living Organisms — Chapter 2: Biological Classification

CBSE Class 11 — Subject: Biology

30:00

Questions: 30 | Duration: 30 minutes

1. Viroids are best described as:

Small circular single-stranded RNA molecules without protein coat Double-stranded DNA viruses Protein-only infectious agents (prions) Bacterial plasmids

2. Viroids primarily infect which group of organisms?

Animals Plants Fungi Bacteria

3. Compared to viruses, viroids lack:

Nucleic acid Any genetic material A protein capsid (coat) Ability to infect hosts

4. The genome of viroids is usually:

Linear double stranded DNA Linear single stranded RNA with poly-A tail Double stranded RNA Circular single stranded RNA

5. Which is a well-known example of a viroid?

Potato spindle tuber viroid (PSTVd) Tobacco mosaic virus (TMV) Human immunodeficiency virus (HIV) Cauliflower mosaic virus (CaMV)

6. Viroids replicate within plant cells by:

Using their own polymerase enzymes Hijacking host RNA polymerase (rolling-circle mechanism) Binary fission Budding from host membrane

7. Viroid RNA often forms extensive internal base pairing resulting in:

Linear single-stranded structure Double-stranded DNA formation Stable highly base-paired secondary structure (rod-like) Immediate degradation by host RNases

8. How are viroids commonly transmitted between plants?

Airborne respiratory droplets Mechanical means (sap transfer), vegetative propagation and insect vectors Sexual contact between plants Water ingestion by animals

9. Viroids do NOT encode which of the following?

Proteins RNA Regulatory RNA functions Secondary structure

10. Detection of viroids in plant tissues is commonly done by:

Gram staining Light microscopy of cell walls Molecular methods (RT-PCR) and hybridization assays Antibody ELISA for viroid coat

11. Which of the following statements is true about viroid pathogenicity?

Viroids always cause severe disease in all hosts Viroid effects vary—symptoms depend on host, viroid strain and environmental conditions Viroids are beneficial to all plants Viroids infect only roots

12. The smallest known pathogens of plants are:

Viroids Bacteria Fungi Nematodes

13. Which feature distinguishes viroids from satellite RNAs?

Satellite RNAs are circular while viroids are linear Viroids always require helper viruses Satellite RNAs depend on a helper virus for replication while viroids do not Viroids have protein coats unlike satellite RNAs

14. Symptoms caused by viroid infection in plants may include:

Increased growth and yield Stunting, leaf deformities, chlorosis and reduced yield Only root rot Immediate death of all plants

15. Which management practice helps prevent spread of viroids in crops?

Applying antibiotics Flooding fields Inoculating with beneficial fungi Using certified disease-free planting material and sanitation of tools

16. Which discovery proved that viroids consist of RNA only?

Visualization under light microscope Nucleic acid extraction and enzymatic digestion showing RNA without protein coat Gram staining Observing under electron microscope showing protein coat

17. A typical size range of viroids is approximately:

250–400 nucleotides (very small) 10,000–20,000 nucleotides 1–2 million base pairs 5–10 kilobases

18. Viroid infection can be spread during vegetative propagation if:

Seeds are always resistant Only insects spread viroids Infected cuttings or tubers are used as planting material Soil pH is low

19. Which method would most reliably distinguish a viroid from a virus?

Observing symptoms only Molecular detection showing circular ssRNA without coat protein genes Gram staining of infected tissue Growth on nutrient agar

20. Which of these is NOT true about viroids?

They can cause plant diseases They have extensive secondary structure They encode a viral coat protein They replicate via host enzymes

21. Which crop has been historically affected by PSTVd?

Potato Rice Wheat Maize

22. Some viroids possess catalytic activity (ribozymes). This means they:

Encode protein enzymes to cut RNA Have RNA sequences that can self-cleave or ligate during replication Use host ribosomes to translate proteins Are made of DNA only

23. Quarantine and certification schemes help control viroids by:

Encouraging use of infected planting material Promoting mixing of stocks from different sources Ensuring only disease-free propagation material is traded and planted Removing all insects only

24. Which lab technique can map the secondary structure of viroid RNA?

Gram staining Nuclease mapping and SHAPE analysis Light microscopy of leaves Electron microscopy of cell walls

25. Which statement about host range of viroids is correct?

Many viroids have a narrow host range, infecting specific plant species Viroids infect all kingdoms equally Viroids prefer animal hosts over plants Viroids can replicate in bacteria easily

26. Which discovery led to the classification of viroids as a distinct class of pathogens?

Discovery of bacteriophages Discovery of plasmids in bacteria Experimental demonstration that PSTVd is an infectious naked RNA without protein Observation of fungal spores

27. Why are viroids not detected by serological tests based on antibodies?

Because viroids are too big for antibodies Because viroids lack proteins and therefore do not elicit specific antibodies to coat proteins Because plant immune systems do not produce antibodies Because antibodies degrade viroids instantly

28. Viroid-induced disease can reduce crop yield primarily by:

Impairing growth and photosynthesis leading to stunting and reduced tuber/fruit production Killing pollinators directly Increasing soil fertility Enhancing seed germination

29. Which control practice is least effective against viroids?

Using certified disease-free stock Disinfecting cutting tools Applying broad-spectrum antibiotics to soil Quarantine infected fields

30. Overall, viroids are important to study because they:

Are useful for human vaccines Represent minimal infectious agents that reveal RNA-based mechanisms of pathogenicity and replication in plants Are identical to viruses in structure and function Replicate independently outside host cells

Prepared fully as per NCERT syllabus — practice for CBSE Board & NEET-UG aspirants.

Titles

Viroids Structure and Characteristics MCQs — CBSE Practice Test
CBSE Class 11 Biology: Viroids Quiz with Automatic Scoring
Viroids: Structure and Characteristics — 30 MCQ Timed Quiz
NCERT Quiz: Viroids Structure and Characteristics (MCQs)
NEET-UG Prep: Viroids Structure and Characteristics Practice Questions

Introduction Paragraph
The Viroids Structure and Characteristics MCQs quiz is designed strictly as per the NCERT Class 11 Biology syllabus. Viroids are the smallest known infectious agents, consisting of circular single-stranded RNA molecules without a protein coat. This 30-question timed quiz helps students understand viroid structure, replication mechanisms, symptoms in plants, and their distinction from viruses. With automatic scoring and instant per-question feedback, the quiz provides students with real-time assessment to strengthen weak areas. Perfect for CBSE Class 11 board exams and NEET-UG aspirants, each question is followed by concise NCERT-style explanations to enhance clarity. This practice test is ideal for self-study, classroom revision, and exam preparation under timed conditions.

Tags
CBSE Class 11 Biology MCQs, Viroids structure and characteristics quiz, NCERT aligned online practice test, Automatic scoring biology MCQs quiz, NEET UG viroids revision quiz, Timed 30 minute MCQ test, Per-question feedback explanations biology, CBSE board exam biology practice

Keywords
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