Viruses Viroids Prions And Lichens

Step 1: Understanding Icosahedral Structure.
An icosahedron is a polyhedron with 20 faces, each an equilateral triangle. It has 12 vertices and 30 edges, making it a highly symmetrical structure often found in viral capsids.

Step 2: Analyzing the options.
(A) 16 triangular facets and 12 vertices: Incorrect — An icosahedron has 20 facets, not 16.
(B) 20 triangular facets and 12 vertices: Correct — This corresponds to the structure of the icosahedron.
(C) 16 triangular facets and 16 vertices: Incorrect — This is not a valid description for the icosahedral structure of a viral capsid.
(D) 20 triangular facets and 16 vertices: Incorrect — While icosahedral structures have 20 facets, they have 12 vertices.

Step 3: Conclusion.
The correct answer is (B) 20 triangular facets and 12 vertices

The correct answer to the question "An organism that causes obstruction of lymphatic system in humans is___" is Wuchereria bancrofti.

Here is the detailed explanation and reasoning:

1. Understanding Lymphatic Filariasis:
   • Lymphatic filariasis, also known as elephantiasis, is a parasitic disease caused by thread-like filarial worms.
   • The condition primarily affects the lymphatic system, leading to a blockage which results in swelling of limbs and other parts of the body.
2. Role of Wuchereria bancrofti:
   • is a parasitic worm responsible for causing lymphatic filariasis.
   • When mosquitoes carrying the larvae of this parasite bite humans, the larvae enter the bloodstream and grow into adult worms within the lymphatic system.
   • The buildup of these worms causes obstruction, impairing the normal flow of lymphatic fluid.
3. Ruling Out Other Options:
   • causes Lyme disease, not related to the lymphatic obstruction.
   • is responsible for brucellosis, a bacterial infection spread from animals to humans, causing fever but no obstruction to the lymphatic system.
   • is the bacterium causing plague, affecting mainly the lungs and bubonic regions but not known for causing lymphatic obstruction.
4. Conclusion:
   • Therefore, the organism that causes obstruction of the lymphatic system, leading to lymphatic filariasis, is Wuchereria bancrofti.