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Select the correct combination of the statements (a–d) regarding the characteristics of certain organisms.
(a) Methanogens are Archaebacteria which produce methane in marshy areas
(b) $Nostoc$ is a filamentous blue-green alga which fixes atmospheric nitrogen
(c) Chemosynthetic autotrophic bacteria synthesize cellulose from glucose
(d) $Mycoplasma$ lack a cell wall and can survive without oxygen
The correct statements are
(a) Methanogens are Archaebacteria which produce methane in marshy areas
(b) $Nostoc$ is a filamentous blue-green alga which fixes atmospheric nitrogen
(c) Chemosynthetic autotrophic bacteria synthesize cellulose from glucose
(d) $Mycoplasma$ lack a cell wall and can survive without oxygen
The correct statements are
A
(b), (c)
B
(a), (b), (c)
C
(b), (c), (d)
D
(a), (b), (d)
Detailed Solution
(a) is correct: methanogens are archaebacteria; they live in marshy areas and in the gut of ruminants and produce methane.
(b) is correct: $Nostoc$ is a filamentous cyanobacterium (blue-green alga) that fixes atmospheric nitrogen in specialised cells called heterocysts.
(c) is wrong: chemosynthetic autotrophic bacteria oxidise inorganic substances such as nitrites, nitrates and ammonia and use the released energy for ATP production; they play a great role in recycling nutrients like nitrogen, phosphorus, iron and sulphur. They do not synthesise cellulose from glucose.
(d) is correct: mycoplasmas completely lack a cell wall, are the smallest living cells known and can survive without oxygen.
Hence the correct statements are (a), (b) and (d).
(b) is correct: $Nostoc$ is a filamentous cyanobacterium (blue-green alga) that fixes atmospheric nitrogen in specialised cells called heterocysts.
(c) is wrong: chemosynthetic autotrophic bacteria oxidise inorganic substances such as nitrites, nitrates and ammonia and use the released energy for ATP production; they play a great role in recycling nutrients like nitrogen, phosphorus, iron and sulphur. They do not synthesise cellulose from glucose.
(d) is correct: mycoplasmas completely lack a cell wall, are the smallest living cells known and can survive without oxygen.
Hence the correct statements are (a), (b) and (d).