Biological Classification: NCERT Class XI (Part 2)

Characters of Kingdom Monera

Kingdom Monera is a classification of organisms that includes prokaryotic organisms, such as bacteria. The main characteristics of the Kingdom Monera are:

Prokaryotic: Monera are unicellular organisms that do not have a defined nucleus or other membrane-bound organelles.
Cell wall: Monera have a cell wall that surrounds their cell membrane, which provides structural support and protection.
Metabolism: Monera have a wide range of metabolic capabilities, including photosynthesis, chemosynthesis, and heterotrophic metabolism.
Reproduction: Monera reproduce asexually through binary fission, where the cell divides into two daughter cells. Some species also reproduce sexually through mechanisms such as conjugation, transduction, and transformation.
Diversity: Monera are incredibly diverse and can be found in nearly every environment on Earth, including soil, water, and living organisms.
Evolution: Monera were the first organisms to evolve on earth and have been around for billions of years. They also have a great adaptive ability to different conditions and environments.

Significance: Monera play an important role in many ecosystem processes such as nutrient cycling and soil formation, and also have significant implications for human health and industry, including the production of antibiotics and other drugs, as well as biotechnology applications.

Bacteria

Bacteria are a type of microorganism that belong to the domain Monera in the three-domain system of classification. The main characteristics of bacteria are:

Prokaryotic: Bacteria are unicellular organisms that do not have a defined nucleus or other membrane-bound organelles.
Cell wall: Bacteria have a cell wall that surrounds their cell membrane, which provides structural support and protection. This cell wall can be composed of peptidoglycan or other complex sugars.
Shape: Bacteria can have different shapes such as spherical (cocci), rod-shaped (bacilli) or spiral (spirilla).
Metabolism: Bacteria have a wide range of metabolic capabilities, including photosynthesis, chemosynthesis, and heterotrophic metabolism. They can be autotrophic, heterotrophic, or mixotrophic.
Reproduction: Bacteria reproduce asexually through binary fission, where the cell divides into two daughter cells. Some species also reproduce sexually through mechanisms such as conjugation, transduction, and transformation.
Diversity: Bacteria are incredibly diverse and can be found in nearly every environment on Earth, including soil, water, and living organisms.

Significance: Bacteria play an important role in many ecosystem processes such as nutrient cycling and soil formation, and also have significant implications for human health and industry, including the production of antibiotics and other drugs, as well as biotechnology applications.

Sub Kingdom Archaebacteria Main Key points

Archaebacteria, also known as archaea, are a type of microorganism that belong to the domain Archaea in the three-domain system of classification. They are similar in appearance to bacteria but have a unique genetic makeup and are often found in extreme environments. The main key points of Archaebacteria are:

Prokaryotic: Archaebacteria are unicellular organisms that do not have a defined nucleus or other membrane-bound organelles.
Cell wall: Archaebacteria have a cell wall that surrounds their cell membrane, which provides structural support and protection. This cell wall can be composed of different types of sugars and lipids than those found in bacteria.
Metabolism: Archaebacteria have a wide range of metabolic capabilities, including photosynthesis, chemosynthesis, and heterotrophic metabolism. They can be found in environments such as hot springs, deep-sea hydrothermal vents, and salt flats.
Reproduction: Archaebacteria reproduce asexually through binary fission, where the cell divides into two daughter cells. Some species also reproduce sexually through mechanisms such as conjugation and transformation.
Diversity: Archaebacteria are incredibly diverse and can be found in a wide range of environments, including extreme environments such as high temperatures, high salinities, and low oxygen levels.
Evolution: Archaebacteria are considered as one of the oldest forms of life on Earth and are thought to have evolved independently from other forms of life.

Significance: Archaebacteria play an important role in many ecosystem processes such as nutrient cycling and are also used in biotechnology applications such as the production of biofuels and other industrial chemicals.

Methanogens

Methanogens are a type of archaea that belong to the domain Archaea in the three-domain system of classification. They are characterized by their ability to produce methane as a byproduct of their metabolism. The main key points of Methanogens are:

Prokaryotic: Methanogens are unicellular organisms that do not have a defined nucleus or other membrane-bound organelles.
Metabolism: Methanogens are obligate anaerobes, meaning they can only survive in environments without oxygen. They use carbon dioxide and hydrogen as their primary source of energy, and produce methane (CH4) as a byproduct of their metabolism.
Habitat: Methanogens are found in a wide range of environments, including freshwater and marine sediments, swamps, rice paddies, and the digestive tracts of ruminants.
Reproduction: Methanogens reproduce asexually through binary fission, where the cell divides into two daughter cells.
Significance: Methanogens play an important role in many ecosystem processes such as nutrient cycling and are also used in biotechnology applications such as the production of methane for fuel, as well as waste water treatment.
Evolution: Methanogens are considered as one of the oldest forms of life on Earth and are thought to have evolved independently from other forms of life.
Biochemistry: Methanogens have unique biochemistry, such as their cell membrane composed of ether-linked lipids and their unique cofactor F420.

Sub Kingdom Eubacteria Main Points

Eubacteria, also known as true bacteria, are a type of microorganism that belong to the domain Bacteria in the three-domain system of classification. They are the most well-known and studied type of bacteria. The main key points of Eubacteria from the NEET exam point of view are:

Prokaryotic: Eubacteria are unicellular organisms that do not have a defined nucleus or other membrane-bound organelles.
Cell wall: Eubacteria have a cell wall that surrounds their cell membrane, which provides structural support and protection. This cell wall can be composed of peptidoglycan or other complex sugars.
Shape: Eubacteria can have different shapes such as spherical (cocci), rod-shaped (bacilli) or spiral (spirilla).
Metabolism: Eubacteria have a wide range of metabolic capabilities, including photosynthesis, chemosynthesis, and heterotrophic metabolism. They can be autotrophic, heterotrophic, or mixotrophic.
Reproduction: Eubacteria reproduce asexually through binary fission, where the cell divides into two daughter cells. Some species also reproduce sexually through mechanisms such as conjugation, transduction, and transformation.
Significance: Eubacteria play an important role in many ecosystem processes such as nutrient cycling, soil formation, and also have significant implications for human health and industry, including the production of antibiotics and other drugs, as well as biotechnology applications.

Medical importance: Eubacteria are responsible for many human diseases such as tuberculosis, tetanus, cholera, and streptococcal infections.

Nostoc

Nostoc is a genus of cyanobacteria that belong to the phylum Cyanobacteria. Cyanobacteria are a type of photosynthetic bacteria that are also known as blue-green algae. Nostoc is known for its ability to form colonies or filaments, and can be found in a wide variety of environments, such as soil, freshwater, and even on surfaces such as mosses and lichens.

Nostoc cells are typically spherical or elliptical in shape, and have a thick, protective sheath that surrounds the cells. They have a unique cell structure, with multiple chloroplasts, mitochondria, and a large nucleoid region where the DNA is located. They are capable of carrying out oxygenic photosynthesis, which means that they can produce oxygen as a byproduct of photosynthesis. Nostoc reproduces asexually by fragmentation, where a filament breaks into smaller pieces and each piece develops into a new filament. Some species can also reproduce sexually by forming thick-walled zygotes. Nostoc is an important primary producer in freshwater and terrestrial ecosystems and is often used as a model organism in the study of photosynthesis and biotechnology.

Anabaena

Anabaena is a genus of cyanobacteria that belong to the phylum Cyanobacteria. Cyanobacteria are a type of photosynthetic bacteria that are also known as blue-green algae. Anabaena is known for its ability to form colonies or filaments and its ability to fix atmospheric nitrogen. It can be found in a wide variety of environments, such as freshwater, soil, and even on surfaces such as mosses and lichens.

Anabaena cells are typically cylindrical in shape, and have a thick, protective sheath that surrounds the cells. They have a unique cell structure, with multiple chloroplasts, mitochondria, and a large nucleoid region where the DNA is located. They are capable of carrying out oxygenic photosynthesis, which means that they can produce oxygen as a byproduct of photosynthesis. Anabaena also contains specialized cells called heterocysts, which are responsible for nitrogen fixation.

Anabaena reproduces asexually by fragmentation, where a filament breaks into smaller pieces and each piece develops into a new filament. Some species can also reproduce sexually by forming thick-walled zygotes. Anabaena is an important primary producer in freshwater and terrestrial ecosystems and is often used as a model organism in the study of photosynthesis, nitrogen fixation and biotechnology.

Chemosynthetic Autotrophic

Chemosynthetic autotrophic organisms are a type of organisms that are able to produce their own food through the process of chemosynthesis. Unlike photosynthetic organisms, which use light energy to produce food, chemosynthetic autotrophic organisms use energy from inorganic compounds to produce organic compounds.

Chemosynthesis occurs in certain bacteria and archaea, and can take place in environments where sunlight is not available, such as deep-sea hydrothermal vents, cold seeps and caves. These organisms use energy derived from the oxidation of inorganic compounds, such as sulfur, ammonia or methane, to fix carbon dioxide into organic compounds such as glucose.

Examples of chemosynthetic autotrophic organisms include:

Sulfur bacteria: These bacteria oxidize sulfur compounds such as hydrogen sulfide to produce energy. They can be found in environments such as hot springs and volcanic vents.
Nitrifying bacteria: These bacteria oxidize ammonia or nitrite to produce energy. They can be found in soil and in the roots of certain plants.
Methanotrophic bacteria: These bacteria oxidize methane to produce energy. They can be found in environments such as swamps and freshwater sediments.

Chemosynthesis is an important process in nutrient cycling and in the survival of organisms in extreme environments. It’s also an important factor in the evolution of life on Earth.

Heterotrophic Bacteria

Heterotrophic bacteria are a type of bacteria that obtain their energy and carbon for growth by consuming organic compounds produced by other organisms. They are not able to produce their own food through photosynthesis or chemosynthesis like autotrophic organisms.

Heterotrophic bacteria can be found in a wide variety of environments, such as soil, water, and within other organisms. They play important roles in nutrient cycling and decomposition, breaking down dead organic matter and recycling nutrients back into the ecosystem. They can also be important in the food industry, as they are used in the production of fermented foods such as yogurt, cheese, and pickles.

Heterotrophic bacteria can be classified into different groups based on their mode of nutrition, such as saprophytic, parasitic and symbiotic. They can also be divided based on their energy source and carbon source. Some examples include:

Aerobic heterotrophic bacteria: These bacteria use oxygen as an electron acceptor and organic compounds as a source of energy and carbon.
Anaerobic heterotrophic bacteria: These bacteria do not use oxygen and instead use other compounds such as sulfur, nitrate, or carbon dioxide as electron acceptors and organic compounds as a source of energy and carbon.

Heterotrophic bacteria can also have a significant impact on human health, both positively and negatively. They can be found in the human gut and play a role in digestion, while others can cause infections and diseases.

The Mycoplasma

Mycoplasma is a genus of bacteria that belongs to the class Mollicutes. These organisms are known for their small size and lack of a cell wall.

Cell structure: Mycoplasmas are small, pleomorphic bacteria that lack a cell wall. This feature makes them resistant to many antibiotics, such as penicillin and cephalosporins, that target the cell wall.
Metabolism: Mycoplasmas are obligate parasites, meaning they require a host to survive. They can infect a wide range of host organisms, including humans, animals, and plants.
Reproduction: Mycoplasmas reproduce by binary fission. They are able to multiply quickly and can cause severe infections in their host organisms.
Disease-causing potential: Mycoplasmas are known to cause a wide range of diseases in humans and animals, including respiratory tract infections, genital tract infections, and some types of arthritis.
Diagnosis: Mycoplasmas can be difficult to detect and diagnose because they lack a cell wall and are small in size. They can be identified through techniques such as PCR, culture, and serological tests.
Treatment: Mycoplasmal infections are typically treated with antibiotics, such as tetracyclines and macrolides, that target the bacterial ribosome, but some Mycoplasma species have developed resistance to these antibiotics.