Characteristics of Kingdom Monera


 


 

Introduction

Kingdom Monera includes all prokaryotic organisms, which are unicellular and lack a well-defined nucleus. This kingdom includes bacteria, archaebacteria, cyanobacteria (blue-green algae), and mycoplasma. Monerans are the most primitive life forms and play a crucial role in ecosystems, being involved in nutrient recycling, nitrogen fixation, and as pathogens.

Characteristics of Kingdom Monera

Kingdom Monera comprises all prokaryotic organisms. These organisms exhibit a variety of characteristics that differentiate them from other kingdoms. Below are the key features of this kingdom:

  1. Prokaryotic Cell Structure:
    • Monerans have a simple prokaryotic cell structure, meaning they lack a membrane-bound nucleus and other organelles.
    • Their genetic material is a single circular DNA molecule located in a region called the nucleoid.
  2. Cell Wall Composition:
    • Most monerans have a rigid cell wall made of peptidoglycan, a polymer that provides structural support and protection to the cell.
    • However, archaebacteria, a subgroup of monerans, have a different cell wall composition that allows them to survive in extreme environments.
  3. Modes of Nutrition:
    • Monerans exhibit diverse modes of nutrition. They can be autotrophic or heterotrophic:
      • Autotrophic: Some monerans, such as cyanobacteria, are autotrophic and can produce their own food through photosynthesis (photosynthetic autotrophs) or chemosynthesis (chemosynthetic autotrophs).
      • Heterotrophic: Most monerans are heterotrophic and rely on other organisms for food. They can be saprophytic (feeding on dead organic matter) or parasitic (feeding on living hosts).
  4. Reproduction:
    • Monerans reproduce asexually through binary fission. Under unfavorable conditions, some bacteria form spores, which allow them to survive harsh environments.
    • In some cases, genetic material can be exchanged between bacteria through conjugation, a primitive form of sexual reproduction.

Conclusion

Kingdom Monera includes the simplest life forms, which are crucial for the functioning of ecosystems. Their ability to survive in diverse habitats, from extreme environments to symbiotic relationships with other organisms, makes them an essential group of organisms on Earth. Understanding their characteristics is important for students preparing for competitive exams like NEET, where questions on prokaryotic organisms are common.

Questions

Q 1. Barophillic prokaroyotes;

(d) readily grown and divides in sea water enriched in any soluble salt of barium;

(c) grow and multiply in very deep marine sediments;

(b) occur in water containing high concentrations of barium hydroxide;

(a) grow slowly in highly alkaline frozen takes at high altitudes;

Q 2. A free living nitrogen fixing cyanobacterium which can also form symbiotic association with the water fern Azolla is;

(d) Anabaena;

(c) Nostoc;

(b) Chlorella;

(a) Tolypothrix;

Q 3. Organisms which obtain energy by the oxidation of reduced inorganic compounds are called;

(d) coproheterotrophs;

(c) saprozoic;

(b) chemoautotrophs;

(a) homoautotrophs;

Q 4. What is true for photolithotrophs?;

(d) Obtain energy from inorganic compounds;

(c) Obtain energy from organic compounds;

(b) Obtain energy from radiations and hydrogen from inorganic compounds;

(a) Obtain energy from radiations and hydrogen from organic compounds;

Q 5. A few organisms are known to grow and multiply at temperatures of \(100-105^{\circ} \mathrm{C}\). They belong to;

(d) thermophilic, subaerial fungi;

(c) hot-spring blue-green algae (cyanobacteria);

(b) thermophilic sulphur bacteria;

(a) marine archaebacteria;

Q 6. The hereditary material present in the bacterium Escherichia coli is;

(d) single stranded RNA;

(c) double stranded DNA;

(b) deoxyribose sugar;

(a) single stranded DNA;

Q 7. Bacterium divides every 35 minutes. If a culture containing \(10^{5}\) cells per \(\mathrm{mL}\) is grown for 175 minutes, what will be the cell concentration per \(\mathrm{mL}\) after 175 minutes?;

(a) \(5 \times 10^{5}\) cells;

(b) \(35 \times 10^{5}\) cells;

(c) \(32 \times 10^{5}\) cells;

(d) \(175 \times 10^{5}\) cells;

Q 8. The plasmid;

(a) helps in respiration;

(b) genes found inside nucleus;

(c) is a component of cell wall of bacteria;

(d) is the genetic part in addition to DNA in microorganisms;

Q 9. Temperature tolerance of thermal blue-green algae is due to;

(a) cell wall structure;

(b) cell organisation;

(c) mitochondrial structure;

(d) homopolar bonds in their proteins;

Q 10. Escherichia coli is used extensively in biological research as it is;

(a) easily cultured ;

(b) easily available;

(c) easy to handle;

(d) easily multiplied in host;

Bacteria in Kingdom Monera


Introduction

Bacteria are the most abundant and diverse group of organisms in Kingdom Monera. They are unicellular, prokaryotic organisms that play a significant role in various ecological processes, such as decomposition, nutrient recycling, and nitrogen fixation. Bacteria are found in nearly every habitat on Earth, from soil and water to extreme environments like hot springs and deep-sea vents.

Characteristics of Bacteria in Kingdom Monera

Bacteria exhibit a range of features that distinguish them from other life forms. These characteristics include:

  1. Cell Structure:
    • Bacteria have a simple prokaryotic structure with no membrane-bound organelles.
    • The cell wall is composed of peptidoglycan, which provides structural support.
    • Some bacteria have an additional outer layer called a capsule, which protects them from the immune responses of hosts.
  2. Shapes of Bacteria:
    • Bacteria come in various shapes, which are often used to classify them:
      • Cocci: Spherical-shaped bacteria (e.g., Streptococcus).
      • Bacilli: Rod-shaped bacteria (e.g., Escherichia coli).
      • Spirilla: Spiral-shaped bacteria (e.g., Spirillum).
      • Vibrio: Comma-shaped bacteria (e.g., Vibrio cholerae).
  3. Metabolism:
    • Bacteria exhibit diverse metabolic capabilities:
      • Autotrophic bacteria: Capable of producing their own food. They can be either photosynthetic (e.g., cyanobacteria) or chemosynthetic.
      • Heterotrophic bacteria: Rely on other organisms for their nutrition. They can be saprophytic or parasitic.
  4. Reproduction:
    • Bacteria reproduce asexually through binary fission, a process where a single bacterial cell divides into two identical cells.
    • Some bacteria can exchange genetic material through processes like conjugation, transformation, or transduction, which contribute to genetic diversity.

Importance of Bacteria

  • Decomposers: Bacteria play a vital role in breaking down dead organic matter and recycling nutrients in ecosystems.
  • Nitrogen Fixation: Certain bacteria, such as Rhizobium, can fix atmospheric nitrogen into a form that plants can use.
  • Pathogens: Some bacteria cause diseases in humans, animals, and plants (e.g., Mycobacterium tuberculosis causes tuberculosis).

Conclusion

Bacteria are an integral part of Kingdom Monera and play a variety of roles in ecosystems, from nutrient recycling to disease causation. Their ability to adapt to diverse environments and their metabolic versatility make them one of the most important groups of organisms on Earth.

Questions

Q 1. In bacteria, plasmid is;

(a) extra-chromosomal material;

(b) main DNA;

(c) non-functional DNA;

(d) repetitive gene;

Q 2. Photosynthetic bacteria have pigments in;

(a) leucoplasts;

(b) chloroplasts;

(c) chromoplasts;

(d) chromatophores;

Q 3. The site of respiration in bacteria is;

(a) episome;

(b) mesosome;

(c) ribosome;

(d) microsome;

Q 4. In bacterial chromosomes, the nucleic acid polymers are;

(a) linear DNA molecule;

(b) circular DNA molecule;

(c) of two types - DNA and RNA;

(d) linear RNA molecule;

Q 5. Sex factor in bacteria is;

(a) chromosomal replicon;

(b) F-replicon;

(c) RNA;

(d) sex-pilus;

Q 6. Genophore bacterial genome or nucleoid is made of;

(a) histones and non-histones;

(b) RNA and histones;

(c) a single double stranded DNA;

(d) a single stranded DNA;

Q 7. Bacteria lack alternation of generation because there is;

(a) neither syngamy nor reduction division;

(b) distinct chromosomes are absent;

(c) no conjugation;

(d) no exchange of genetic material;

Q 8. Bacterial leaf blight of rice is caused by a species of;

(a) Xanthomonas;

(b) Pseudomonas;

(c) Alternaria;

(d) Erwinia;

Q 9. In eubacteria, a cellular component that resembles eukaryotic cells is;

(d) plasma membrane;

(c) cell wall;

(b) ribosomes;

(a) nucleus;

Q 10. The chief component of bacterial cell wall is;

(a) Cellulose and chitin;

(b) Cellulose and pectin;

(c) Amino acids and polysaccharides;

(d) Cellulose and carbohydrates;

Archaebacteria in Kingdom Monera


Introduction

Archaebacteria, also known as archaea, are a unique group of prokaryotes that differ from true bacteria (eubacteria) in several key aspects. They are extremophiles, meaning they thrive in extreme environmental conditions, such as high temperatures, acidity, or salinity. Archaebacteria are considered one of the oldest forms of life on Earth.

Characteristics of Archaebacteria in Kingdom Monera

Archaebacteria exhibit several unique characteristics:

  1. Cell Wall Composition:
    • Unlike eubacteria, archaebacteria lack peptidoglycan in their cell walls. Instead, their cell walls are composed of unique lipids and proteins, which enable them to survive in harsh environments.
  2. Membrane Structure:
    • The cell membrane of archaebacteria is composed of ether-linked lipids, which provide stability in extreme conditions. This is in contrast to the ester-linked lipids found in eubacteria and eukaryotes.
  3. Types of Archaebacteria:
    • Archaebacteria are classified into different groups based on the environments in which they thrive:
      • Methanogens: Produce methane as a byproduct of their metabolism. They are found in anaerobic environments, such as swamps and the guts of ruminants.
      • Halophiles: Thrive in extremely salty environments, such as salt lakes.
      • Thermoacidophiles: Live in hot and acidic environments, such as hot springs and volcanic vents.
  4. Metabolism:
    • Archaebacteria exhibit diverse metabolic pathways. Some are autotrophic, obtaining energy through chemosynthesis, while others are heterotrophic.

Importance of Archaebacteria

  • Biotechnology: Enzymes from archaebacteria, such as DNA polymerases from Thermus aquaticus, are used in PCR (polymerase chain reaction) technology.
  • Ecological Role: Archaebacteria play a crucial role in extreme ecosystems and contribute to global biogeochemical cycles.

Conclusion

Archaebacteria are a distinct group of prokaryotes with unique adaptations that allow them to thrive in extreme environments. Their differences from eubacteria, especially in cell wall and membrane composition, make them an important subject of study in evolutionary biology and biotechnology.

Questions

Q 1. What is true for archaebacteria?;

(a) All halophiles;

(b) All photosynthetic;

(c) All fossils;

(d) Oldest living beings;

Q 2. Archaebacteria differ from eubacteria in;

(a) cell membrane structure;

(b) mode of nutrition;

(c) cell shape;

(d) mode of reproduction;

Q 3. In the five kingdom system of classification, which single kingdom out of the following can include blue-green algae, nitrogen fixing bacteria and methanogenic archaebacteria ?;

(a) Monera;

(b) Fungi;

(c) Plantae;

(d) Protista;

Cyanobacteria in Kingdom Monera


Introduction

Cyanobacteria, also known as blue-green algae, are photosynthetic prokaryotes that belong to Kingdom Monera. They are capable of producing oxygen through photosynthesis, making them crucial contributors to Earth's oxygen supply. Cyanobacteria are found in diverse aquatic environments, including freshwater and marine habitats.

Characteristics of Cyanobacteria in Kingdom Monera

  1. Photosynthesis:
    • Cyanobacteria contain chlorophyll a, the same pigment found in plants, which allows them to perform photosynthesis.
    • They release oxygen as a byproduct of photosynthesis, contributing to the oxygenation of Earth's atmosphere during early evolutionary history.
  2. Cell Structure:
    • Cyanobacteria have a prokaryotic cell structure, with no membrane-bound organelles.
    • Their cells contain thylakoid membranes, where photosynthesis occurs.
  3. Nitrogen Fixation:
    • Some cyanobacteria, such as Anabaena and Nostoc, are capable of nitrogen fixation, converting atmospheric nitrogen into a form usable by plants. These cyanobacteria possess specialized cells called heterocysts for nitrogen fixation.
  4. Reproduction:
    • Cyanobacteria reproduce asexually through binary fission. They can also form resistant spores called akinetes, which allow them to survive unfavorable conditions.

Importance of Cyanobacteria

  • Ecological Role: Cyanobacteria play a crucial role in aquatic ecosystems by producing oxygen and serving as primary producers in the food chain.
  • Agricultural Importance: Nitrogen-fixing cyanobacteria are used as biofertilizers in paddy fields to enhance soil fertility.