Test: Kingdom Monera - 1 - NEET MCQ

The cyanobacteria are unicellular, colonial or filamentous, freshwater/marine or terrestrial algae. The colonies are generally surrounded by gelatinous sheath. They often form blooms in polluted water bodies.

Some of the bacteria are autotrophic, i.e., they synthesise their own food from inorganic substrates. They may be photosynthetic autotrophic or chemosynthetic autotrophic.

Chemosynthetic autotrophic bacteria oxidise various inorganic substances such as nitrates, nitrites and ammonia and use the released energy for their ATP production. They play a great role in recycling nutrients like nitrogen, phosphorous, iron and sulphur.

Let's examine the features:

(a) Incorrect. Kingdom Monera includes prokaryotic cells, which do not have a nucleus or membrane-bound organelles.

(b) Correct. Monerans (bacteria) can be autotrophic (e.g., cyanobacteria) or heterotrophic (e.g., most bacteria).

(c) Correct. Monera has been divided into two domains: Archaeabacteria and Eubacteria.

(d) Incorrect. only Bacteria are the sole members of the Kingdom Monera

(B) - Mycoplasma is pathogenic to both animals and plants.
- These organisms lack cell walls and can survive without oxygen.
 

BOTH statements are true but reason is not the correct explaination of assertion 

Archaebacteria are special since they live in some of the most harsh habitats such as extreme salty areas (halophiles), hot springs (thermoacidophiles) and marshy areas (methanogens). Archaebacteria differ from other bacteria in having a different cell wall structure and this feature is responsible for their survival in extreme conditions
.

Heterocysts in cyanobacteria, such as Nostoc and Anabaena, serve the crucial function of nitrogen fixation. These specialized cells enable the conversion of atmospheric nitrogen into a form that can be utilized by the organism. This process is essential for the cyanobacteria to thrive in environments with limited nitrogen availability, contributing to the recycling of nutrients and supporting the overall ecosystem.

 Both (A) and (R) are true and (R) is the correct explanation of (A).
- Archaebacteria are unique bacteria that live in extreme environments like hot springs, acidic environments, and salt flats.
- Their ability to survive in such harsh habitats showcases their special nature.
- The reason given, that they live in harsh habitats, indeed explains why Archaebacteria are considered special.
- Therefore, option A is the correct choice.A)

The three-domain system has also been proposed that divides the Kingdom Monera into two domains, leaving the remaining eukaryotic kingdoms in the third domain and thereby a six kingdom classification

Heterotrophic bacteria are most abundant in nature. The majority are important decomposers. Many of them have a significant impact on human affairs. They are helpful in making curd from milk, production of antibiotics, fixing nitrogen in legume  roots, etc. Some are pathogens causing damage to human beings, crops, farm animals and pets. Cholera, typhoid, tetanus, citrus canker are well known diseases caused by different bacteria.