Select the correct combination of the statements (i – iv) regarding the characteristics of certain organisms. (i) Methanogens are archaebacteria which produce methane in marshy areas. (ii) Nostoc is a filamentous blue-green alga which fixes atmospheric nitrogen. (iii) Chemosynthetic autotrophic bacteria synthesise cellulose from glucose. (iv) Mycoplasma lack a cell wall and can survive without oxygen. The correct statements are
- (ii) and (iii)
- (i), (ii) and (iii)
- (ii), (iii) and (iv)
- (i), (ii) and (iv)
Answer
(4) (i), (ii) and (iv)
Solution
(i) Correct: as per NCERT, methanogens are archaebacteria present in marshy areas and in the gut of ruminants; they produce methane (biogas).
(ii) Correct: Nostoc is a filamentous cyanobacterium (blue-green alga) with heterocysts that fix atmospheric nitrogen.
(iii) Incorrect: chemosynthetic autotrophic bacteria oxidise inorganic substances (nitrates, nitrites, ammonia) and use the released energy for ATP production; they do not synthesise cellulose from glucose.
(iv) Correct: as per NCERT, Mycoplasma completely lack a cell wall and can survive without oxygen.
∴ The correct statements are (i), (ii) and (iv).
Answer: (4)