Question

Which of the following statements about Kingdom Monera is not true?

• A. All bacteria are heterotrophs
• B. Cyanobacteria are photosynthetic
• C. Anabaena is a cyanobacterium
• D. Methanogens live in harsh habitats

Hint:

Remember that bacteria show every major nutritional mode. Therefore, statements beginning with “all bacteria are heterotrophs” are usually incorrect.

Answer 1

The Correct Option is A

Concept: Kingdom Monera includes all prokaryotic organisms. Bacteria exhibit remarkable diversity in nutrition and habitat. They may be:
• Autotrophic
• Heterotrophic
• Photosynthetic
• Chemosynthetic Therefore, not all bacteria have the same nutritional mode.

Step 1: Examine Option (A)
Many bacteria are heterotrophic, but several bacteria are autotrophic. Examples:
• Cyanobacteria are photosynthetic autotrophs.
• Nitrifying bacteria are chemosynthetic autotrophs. Hence, the statement that all bacteria are heterotrophs is false.

Step 2: Examine Option (B)
Cyanobacteria contain chlorophyll and perform photosynthesis. Thus, this statement is true.

Step 3: Examine Option (C)
Anabaena is a filamentous cyanobacterium capable of nitrogen fixation. Thus, this statement is true.

Step 4: Examine Option (D)
Methanogens are archaebacteria that inhabit anaerobic and extreme environments such as marshes and the rumen of cattle. Hence, this statement is true. \[ \boxed{\text{(A) All bacteria are heterotrophs}} \]