Question

Evolutionary relationship of three major group
of organisms is shown in the accompanying
diagram, where A, B, C are Archaebacteria,
Eubacteria and
Cyanobacteria respectively. The Nostoc
bacteria will be placed
C
Hв
(1) On brahch A
(2) On branch B
(3) On branch C
(4) On branch A or on branch C​

Answer 1

Answer:

nostoc will be placed in cyanobacteria i.e. in C

Answer 2

Answer:

The Nostoc bacteria will be placed on branch C.

Explanation:

Kingdom Monera

The sole members of the kingdom Monera are bacteria. They are the unicellular prokaryotes based on their evolutionary relationships, they are categorized into two main classes:

A] Archaebacteria:

• These are the most primitive class of bacteria and live in the harshest habitats like salty areas (halophiles), hot volcanic springs (thermoacidophiles), the gut of ruminant animals (methanogens), etc.
• Their cell wall structure (extensive cross-linking) aids their survival in such areas.

B] Eubacteria:

• These are the 'true' bacteria characterized by a rigid cell wall
• They may be motile (bearing flagella) or non-motile
• They are again sub-divided into three main categories based on their mode of nutrition:
  1. Photosynthetic autotrophs: These are the cyanobacteria (also known as blue-green algae [BGA]) and may be unicellular, colonial or filamentous, living in terrestrial/aquatic habitats.
  They often form 'blooms' in polluted water.
  Some of them may be capable of fixing atmospheric N₂ in specialised cells known as heterocyst. E.g., Nostoc and Anabaena.
  They are the most advanced group of bacteria.
  2. Chemosynthetic autotrophs: These bacteria synthesize food via inorganic molecules like nitrates & nitrites, ammonia, sulphides, phosphates, etc. and not directly by harnessing solar energy. Thus, they can also survive in dark.
  3. Heterotrophic bacteria: These are the most abundant of all bacteria and the majority of them are decomposers.
• Mycoplasma: They are the smallest cell organisms known and lack a cell wall. They are capable of surviving without oxygen. They are mostly pathogens causing diseases/infections in plants and animals.

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