2002 General Studies, all questions
UPSC Prelims 2002 · General Studies
Question 134: Science and Technology
Which one of the following statements is correct?
aPrions are the smallest free-living cells
bThe cell wall of Mycoplasmas is made up of amino sugars
cViroids consist of a single-stranded RNA molecule
dRickettsia’s lack cell wall
AnswerThe answer is (c).
Viroids are infectious particles made of a short single-stranded circular RNA with no protein coat, known as agents of plant diseases. The other statements are wrong: prions are infectious proteins, not cells; Mycoplasmas are the smallest free-living cells and have no cell wall; and Rickettsiae do have a cell wall.
Why each option is right or wrong
- (a) Prions are infectious proteins, not cells; Mycoplasmas are the smallest free-living cells.
- (b) Mycoplasmas have no cell wall at all.
- (c) Right: viroids are single-stranded RNA molecules.
- (d) Rickettsiae do have a cell wall.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2002, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.