Q.59 Given below are two statements:
An icosahedron is a regular polyhedron with 60 equilateral triangular faces and 20 vertices.
The simplest virion consists of a nucleocapsid, which is composed of nucleic acid,
either DNA or RNA, and a protein coat called a capsid.
In the light of the above statements, choose the correct answer
from the options given below:
- Both Statement I and Statement II are correct
- Both Statement I and Statement II are incorrect
- Statement I is correct but Statement II is incorrect
- Statement I is incorrect but Statement II is correct
Statement I is incorrect but Statement II is correct.
Statement I Analysis
An icosahedron is a regular polyhedron (Platonic solid) with 20 equilateral triangular faces, 12 vertices, and 30 edges—not 60 faces and 20 vertices as stated. The confusion may arise from the dodecahedron (12 pentagonal faces, 20 vertices) or truncated icosahedron (soccer ball shape with 32 faces, 60 vertices).
Statement II Analysis
The simplest virion structure is indeed a nucleocapsid: genomic nucleic acid (DNA or RNA) enclosed by a protein capsid. This naked virus lacks an envelope, as seen in poliovirus or adenoviruses, protecting the genome during infection.
Option Breakdown
Option Evaluation Reason Both Statement I and Statement II are correct Incorrect Icosahedron has 20 faces/12 vertices, not 60/20. Both Statement I and Statement II are incorrect Incorrect Virion nucleocapsid definition is accurate. Statement I is correct but Statement II is incorrect Incorrect Geometry error; virion fact holds. Statement I is incorrect but Statement II is correct Correct Matches verified icosahedron properties and virology basics. Icosahedron faces vertices define its Platonic solid geometry, while simplest virion nucleocapsid forms the basic virus particle in biology exams like NEET.
Icosahedron Geometry Properties
Regular icosahedron features 20 equilateral triangular faces, 12 vertices (5 triangles meet per vertex), and 30 edges. Mistaking it for 60 faces/20 vertices confuses it with truncated forms or dodecahedrons.
Simplest Virion Structure
Simplest virion consists of nucleocapsid: nucleic acid genome (DNA/RNA) surrounded by protective protein capsid. Non-enveloped viruses exemplify this minimal infectious unit.
Viral Capsid Symmetry
Many capsids adopt icosahedral symmetry for efficient genome packaging, linking geometry to virology—20 faces maximize surface for subunits.
Exam Strategy
Assertion questions on icosahedron faces vertices simplest virion nucleocapsid test geometry recall; option D fits due to Statement I error.
