Kingdom Monera
All the bacteria including blue-green algae or cyanobacteria are a part of the Kingdom Monera The only prokaryotic Kingdom out of all the kingdoms is Monera as they include bacteria that lack a true nucleus. Kingdom Monera also constitutes the most numerous living cellular organisms. Some of the cyanobacteria and actinomycetes are multicellular while most of the bacteria are unicellular.
Kingdom Monera comprises the bacteria and cyanobacteria that are usually known as blue-green algae. While only bacteria are prokaryotic and lack a true nucleus, (which means without a nuclear membrane). The only prokaryotic plant kingdom is Monera. Bacteria were the first cellular organisms to develop on the earth since the afterlife was initiated around 3.5 billion years ago and they are the single cellular organisms on the planet earth for about the next two billion years.
Most bacteria are unicellular or single-celled but some cyanobacteria and actinomycetes are multicellular and filamentous in which filaments might be branched. Monerans are also the most abundant of all living cellular organisms.
Kingdom Monera- Classification
The three sub-kingdoms of the Monera Kingdom are listed below-
Archaebacteria- These are found in the most extreme habitats like hot springs, marshy areas, and salty areas. They have a special cell wall that helps them to survive in extreme conditions. These have a unique nucleotide sequence for their rRNA and tRNA. They have an autotrophic mode of nutrition. Examples are- Ignicoccus hospitalis and Aeropyrum pernix.
Eubacteria (true bacteria)- These have a cell wall that is rigid and made of peptidoglycans. These bacterias move with the help of flagella and some of the bacteria contains pili which are short appendages on the surface of the cell which helps them during sexual reproduction. Examples are- Clostridium and Rhizobium.
Cyanobacteria- These are photosynthetic in nature and are also called blue-green algae. These bacteria contain carotenoids and phycobilins and chlorophyll and are found mostly in the aquatic region. Examples are- Spirulina, Nostoc, and Anabaena.
Kingdom Monera- Functions
Functions of Monerans classified on the basis of Nutrition, Respiration, and Reproduction as listed below-
Monerans have four types of nutritional categories which include autotrophs, saprotrophs, symbionts, and parasites.
Respiration can be aerobic and anaerobic. Cellular respiration occurs in the inner extensions of the cell membrane which are known as mesosomes.
Reproduction can also be of two types- sexual and asexual. Genetic recombination takes place in sexual reproduction while asexual reproduction is done by binary fission.
Kingdom Monera- Characteristics
These are unicellular organisms.
Ribosomes present are of 70S type.
No nuclear membrane bounds the DNA.
Mitochondria, plastid lysosomes, golgi bodies, endoplasmic reticulum, and some other cell organelles are not present.
The cell wall is made of peptidoglycan.
The locomotory organ is the flagella.
These are also known as environmental decomposers.
Kingdom Protista
Kingdom Protista includes unicellular eukaryotes such as diatoms, protozoa, and unicellular algae. These are neither animals nor plants nor fungi. Water or environments which are damp terrestrial are where protists live.
They have membrane-bound organelles like a nucleus with chromosomes covered in the nuclear membrane, chloroplast (only in photosynthetic protists), mitochondria, and endoplasmic reticulum, and golgi bodies. Here, the respiratory organelles are mitochondria.
Protista is parasitic, photosynthetic or saprotrophic.
Unlike bacteria, Protista would have flagella or cilia having 9 + 2 microtubules which consist of only one spirally protein (flagellin). They can reproduce both sexually and asexually. Some protists are harmful and some are beneficial to human beings.
Kingdom Protista- Classification
The three phyla of Kingdom Protista are listed below-
Kingdom Protista- Functions
80% of the earth’s oxygen is provided by the blue-green algae. Brown-algae and blue-green algae are grown for the production of biofuel.
They are the foundation of the food chain and act as primary producers.
These are symbionts which means they have a close relationship between two species where one is benefitted.
Kingdom Protista- Characteristics
The organelles are membrane-bound. For example, a nucleus has chromosomes enclosed in the nuclear membrane, chloroplast, mitochondria, endoplasmic reticulum, or Golgi bodies.
Respiratory organelles are mitochondria.
These can either be photosynthetic, parasitic, or saprotrophic.
Cilia or flagella are used for locomotion.
Reproduction can be sexual as well as asexual.
Kingdom Fungi
During the warm humid season, chapati, bread slices, leather shoes, and belts, develop a dusty layer on them. In flower beds and lawns, mushrooms pop out and these are called fungi.
Kingdom Fungi includes eukaryotic organisms that are omnipresent and have a cell wall. Microorganisms like yeasts, mushrooms, and molds are eukaryotic organisms that are classified under the Kingdom Fungi.
Kingdom Fungi- Classification
Classification of the Kingdom Fungi can be done on the basis of mode of nutrition and spore formation.
Kingdom Fungi- Functions
These are responsible for the breakdown of organic matter which releases carbon, nitrogen, phosphorus, and nitrogen into the soil as well as the atmosphere.
These are used in many industrial and household processes like wine-making, beer-making, bread-making, cake-baking, and certain cheese.
Kingdom Fungi- Characteristics
These are heterotrophic multicellular or unicellular eukaryotes.
Cell walls are made of chitin.
Thread-like slender filaments are known as hyphae which are divided by partitions called septa in the cells.
The network formed by a group of hyphae is known as the mycelium.
These do not have chlorophyll.
Aquatic fungi have flagellate spores or flagellate gametes. At any stage of the life cycle, higher fungi don't have a flagellum.
Reproduction in fungi can be both sexual by means of conjugation and asexual by flagellate or non-flagellate spores.
Main Kinds of Fungi
Fungi can be classified into five main kinds. They are
Myxomycetes, the slime molds that have an irregular shape. They have a creeping multinucleate mass of protoplasm sometimes enclosing up to several square meters.
Phycomycetes, are unicellular, branched, and filamentous. Example: Phytophthora and Rhizopus.
Ascomycetes, single-celled or multicellular. Example: Penicillium, Aspergillus, and Neurospora.
Basidiomycetes, multicellular, branched and are characterized by smuts, rusts, toadstools, and mushrooms that are large enough so that they can be viewed through naked eyes.
Deuteromycetes, multicellular filamentous branched fungi reproduce by asexual means alone. Example: Alternaria.
Mycorrhizae and lichens exist in symbiotic relationships. Lichens are the combination of definite fungus and a blue-green or green alga that prepares food while the fungus aids in protection and absorbs minerals and water from the neighboring places.
FAQs on Kingdom Monera, Protista and Fungi
1. What are the fundamental differences between Kingdom Monera, Protista, and Fungi?
The key differences between these three kingdoms lie in their cellular organisation, cell wall composition, and mode of nutrition. Here’s a comparison:
- Kingdom Monera: Consists of prokaryotic, unicellular organisms. They lack a true nucleus and other membrane-bound organelles. Their cell wall is made of peptidoglycan. Examples include bacteria and cyanobacteria.
- Kingdom Protista: Includes eukaryotic, mostly unicellular organisms. They possess a true nucleus and membrane-bound organelles. Their cellular structure is more complex than Monerans. Examples include amoeba, diatoms, and paramecium.
- Kingdom Fungi: These are eukaryotic, heterotrophic organisms that can be unicellular (like yeast) or multicellular (like mushrooms). Their cell walls are uniquely composed of chitin, and they obtain nutrients by absorption.
2. What are the major groups classified under Kingdom Monera, with examples?
Kingdom Monera is broadly divided into three main sub-kingdoms based on their characteristics and habitat:
- Archaebacteria: Known as ancient bacteria, they live in some of the most extreme habitats. Examples include methanogens (in marshy areas), halophiles (in salty areas), and thermoacidophiles (in hot springs).
- Eubacteria: Referred to as 'true bacteria', they have rigid cell walls and, if motile, possess flagella. Examples include Rhizobium (nitrogen-fixing bacteria) and Clostridium.
- Cyanobacteria: Also known as blue-green algae, these are photosynthetic autotrophs. They contain chlorophyll and are often found in aquatic environments. Examples include Nostoc and Spirulina.
3. Why are Monerans considered the most primitive organisms, and what adaptations allow them to survive in extreme environments?
Monerans are considered the most primitive life forms because they are prokaryotic, representing the simplest type of cellular organisation. Their early evolution, around 3.5 billion years ago, places them at the base of the evolutionary tree. Their ability to survive in extreme conditions, especially among Archaebacteria, is due to a unique cell wall structure that lacks peptidoglycan but contains complex lipids. This structure provides protection against high temperatures, extreme salinity, and acidic conditions where other organisms cannot survive.
4. How does the mode of nutrition in Kingdom Fungi differ from that of other heterotrophs?
Unlike animals (other heterotrophs) that ingest and then digest food, fungi exhibit an absorptive mode of nutrition. They secrete digestive enzymes into their surroundings to break down complex organic matter externally. The resulting simple, soluble molecules are then absorbed directly through their cell walls. This makes them excellent decomposers (saprophytes) or effective parasites and symbionts.
5. What is the economic importance of Kingdom Protista in various ecosystems?
Kingdom Protista has significant economic and ecological importance. Phytoplankton, such as diatoms, are the primary producers in aquatic food chains, forming the base of the food web and producing a substantial amount of Earth's oxygen through photosynthesis. Some protists are harvested for industrial applications; for example, diatomaceous earth (from fossilised diatoms) is used in filtration and as an abrasive. They also play a crucial role in nutrient cycling.
6. How are fungi classified? Provide examples for each major group.
Fungi are primarily classified into major groups based on their reproductive structures and the morphology of their mycelium:
- Phycomycetes: Often called algal fungi, they have aseptate (coenocytic) hyphae. Examples include Rhizopus (bread mould) and Albugo (parasitic fungi on mustard).
- Ascomycetes: Known as sac fungi, they produce spores in a sac-like structure called an ascus. Examples include Penicillium, Aspergillus, and Saccharomyces (yeast).
- Basidiomycetes: Called club fungi, they bear spores on club-shaped structures called basidia. This group includes mushrooms, puffballs, and rusts like Agaricus (mushroom).
- Deuteromycetes: Known as 'imperfect fungi' because their sexual reproduction stage is unknown. They reproduce asexually. Examples include Alternaria and Trichoderma.
7. Although both have cell walls, how does the cell wall of Fungi fundamentally differ from that of plants, and what is the functional significance?
The fundamental difference lies in their chemical composition. The cell wall of Fungi is made of chitin, a strong, flexible nitrogen-containing polysaccharide. In contrast, the cell wall of plants is made of cellulose. Functionally, chitin provides structural support and protection from desiccation and predators. This chemical distinction is a key reason why fungi are placed in a separate kingdom from plants, highlighting a different evolutionary path despite their superficial similarities in being sessile.
8. What are lichens and mycorrhizae, and why are these symbiotic relationships involving fungi so important?
Lichens and mycorrhizae are two critical examples of symbiotic relationships involving fungi.
- Lichens are a composite organism arising from a symbiotic relationship between a fungus (the mycobiont) and an alga or cyanobacterium (the phycobiont). The fungus provides shelter and absorbs water and minerals, while the alga performs photosynthesis. They are important ecological indicators of air pollution.
- Mycorrhizae is a symbiotic association between a fungus and the roots of higher plants. The fungus helps the plant absorb essential nutrients like phosphorus from the soil, while the plant provides the fungus with carbohydrates. This relationship is vital for the growth of over 90% of terrestrial plants.
