The Kingdoms Monera, Protista & Fungi : 12th Class Biology Notes (Lesson 2 ) – NIOS
- Since only bacteria are prokaryotic (lacking a true nucleus, that is without a nuclear membrane), Monera is the only prokaryotic kingdom.
- Bacteria were the first cellular organisms.
- Most bacteria are unicellular but actinomycetes and some cyanobacteria are multicellular and filamentons.
Structure of a bacterial cell
- The single celled bacterium has a cell wall made of the compound peptidoglycan covering the cell membrane; and a single circular chromosome.
- Some bacteria move with the help of one or more flagella.
- Plasma membrane, present below the cell wall, encloses the cytoplasm and othercell contents. It is made up of lipids and proteins, as in eukaryotes.
- One circular chromosome made of a double helical molecule of DNA is located ina region of the cytoplasm called nucleoid.
- Membrane bound cell organelles like endoplasmic reticulum, mitochondria, chloroplast,and golgi complex are absent.
Prokaryotes have no nuclear membrane around genetic material and no membrane bound cell organelles except mesosomes. They have only the 70s ribosomes.
Monera – General body functions
The four nutritional categories found in bacteria are :
- Autotrophs – synthesize their own organic food.
- Saprotrophs – feed on dead organic matter.
- Symbionts – use food from other living organisms with which they are associated for mutual benefit.
- Parasites – absorb food from living organisms and cause harm to them
Respiration in bacteria may be either
aerobic i.e. using oxygen for respiration or
anaerobic i.e. respiration in the absence of oxygen.
Cellular respiration or breakdown of food to release energy occurs in mesosomes.
- Asexual Reproduction : Bacteria reproduce asexually by binary fission
- Sexual Recombination (=Genetic Recombination) : Some bacteria show a primitive mode of sexual reproduction. It is different from sexual reproduction in higher forms.
Beneficial and harmful bacteria
Diseases Caused By Bacteria
- Vibrio cholerae – Cholera
- Salmonella typhi – Typhoid
- Clostridium tetani (क्लॉस्ट्रीडियम टिटेनी) – Tetanus
- Corynebacterium diphtheriae (कोरिनबैक्टीरियम डिप्थीरिआई) – Diphtheria
- Mycobacterium tuberculosis – Tuberculosis
Beneficial Activities of Bacteria
- Rhizobium – Found in roots of legumes, like Peas, grams, Pulses etc, where it fixes atmospheric nitrogen as ammonia, which is then convertedinto useful amino acid. (वायुमंडलीय नाइट्रोजन को अमोनिया के रूप में स्थिर कर देता है।)
- Azotobacter – Makes the soil fertile. It fixes atmospheric nitrogen in the soil.
- Streptomyces – Produces Streptomycin antibiotic.
- Lactobacillus – Ferments lactose (milk sugar) to lactic acid. This helps in setting of milk into curd.
- Methanogenic bacteria – Sewage treatment (वाहित मल के विघटन में सहायता)
Differences between Bacteria and Cyanobacteria
|1||Smaller cells||Comparatively larger cells|
|2||May have flagella||Do not have flagella.|
|3||Some bacteria (green) carry out photosynthesis in a different way and do not release oxygen (anoxygenic)||They all carry out photosynthesis in the usual manner as in green plants and release oxygen (oxygenic)|
|4||Sexual recombination by conjugation in some bacteria||Sexual recombination has been observed in some cyanobacteria.|
Kingdom Monera includes three groups, viz.
- Eubacteria, and
1. Archaebacteria includes bacteria that live in unusual environments particularly at lowlevels of oxygen.
Main types of Archaebacteria are :
- Methanogenic bacteria that live in sewage and intestinal tracts of animals.
- Thermoacidophilic bacteria that live in hot springs.
- Halophilic bacteria which live in salty conditions where hot sun concentrates sea water.
2. Eubacteria include all other bacteria excluding cyanobacteria.
3. All cyanobacteria are oxygenic photoautotrophs.
KINGDOM PROTOCTISTA / PROTISTA (UNICELLULAR EUKARYOTES)
- Protoctista are unicellular eukaryotes. Protozoa, diatoms and unicellular algae are included in it.
- They have membrane bound organelles
- Mitochondria are the respiratory organelles.
- Protoctists are either photosynthetic, parasitic or saprotrophic.
- For locomotion, protoctists may have cilia or flagella.
- They reproduce both asexually and sexually.
Classification of Protoctista (Protista)
The kingdom protoctista includes –
Phylum Protozoa which has the following four classes :
- Rhizopoda : Example, Amoeba
- Flagellata : Example, Euglena
- Ciliata : Example, Paramecium
- Sporozoa : Example, Plasmodium
The protistan algae belong to
- Phylum Bacillariophyta : Example diatoms
- Phylum Chlorophyta : Example Chlorella
Some examples of Protoctists :-
- Amoeba is commonly found in the mud, in freshwater ponds and ditches containing decaying leaves.
- It has blunt pseudopodia for locomotion.
- It captures food by pseudopodia to form a food vacuole.
- Asexual reproduction is by binary fission.
- One common species is Entamoeba histolytica which caues amoebic dysentery in humans.
- The new host gets infected when the cyst is swallowed along with contaminated food or water.
- The cyst bursts and releases Entamoeba in the intestines where it causes local abscesses (open injury).
- The symptoms of amoebic dysentery are abdominal pain, nausea and presence of bloodand mucus with stool.
Plasmodium (The malarial parasite)
- The life cycle of Plasmodium has both asexual and sexual phases.
- The asexual phase is spent in the human blood.
- Sexual phase is spent in the female Anopheles mosquito.
Male Anopheles cannot cause malaria as it feeds on plant juices and not the human blood.
Euglena – A freshwater Flagellate
Euglena is abundantly found in stagnant waters such as pools, ponds and ditches containing decaying organic matter.
the organism has the following parts –
- Pellicle – elastic body covering made up of protein.
- Stigma or eyespot – a prominent red pigment spot. It is sensitive to light.
- Contractile Vacuole – for osmoregulation.
- Flagellum – for propulsion in water.
- Chloroplast – contain green coloured chlorophyll for photosynthesis.
- Reproduction – is by binary fission.
- The diatoms are found in both fresh and salt water and in moist soil.
- Thousands of species of diatoms act as food foraquatic animals.
- Diatoms are either unicellular, colonial or filamentous and occur in a wide variety of shapes.
- Each cell has a single prominent nucleus and plastids.
- They produce shells (cell walls) containing silica.
- Algae can be unicellular e.g. Chlamydomonas or multi-cellular like Spirogyra.
- Algae can prepare their own food by photosynthesis as they contain chlorophyll.
- Some algae have other pigments also e.g. blue pigment (Phycocyanin), a brown pigment (Fucoxanthin) or a red pigment (Phycoerythrin).
- Depending on the pigment present, the algae are called blue, green, brown or red algae.
Colour of the Red Sea is due to the dominan to ccurrence of a blue-green alga, Trichodesmium erythraeus
- Structurally the algae have a definite cell wall, cell membrane, a nucleus, cytoplasm and choloroplast.
- The chloroplast is cup-shaped in Chlamydomonas and ribbon-shaped in Spirogyra.
- Pyrenoids, the starch containing bodies are integral part of chloroplasts in green algae.
Usefulness of Algae
- Provide food for fish.
- These are rich sources of vitamins A and E.
- Many marine forms are important sources of iodine, potassium and other minerals.
- Blue-green algae increase the soil fertility by fixing atmospheric nitrogen.
- Blue-green algae that fix atmospheric nitrogen, are a source of natural fertilizer for the crop plants.
- A group of algae (diatoms) deposit silica in their walls.
- After their death these algae are preserved as fossils.
- Their siliceous deposits in large amounts result in the formation of diatomaceous earths that are used as filters, and for lining of furnaces.
During warm humid days slices of bread, chapati, leather belts or shoes, developa powdery layer on them. In lawns and flower beds, mushrooms come out. Theseare all fungi.
Characteristics of Fungi
- Fungi are heterotrophic unicellular or multicellular eukaryotes.
- Fungi exist as slender thread like filaments called hyphae. Hypha may be one celled or multi celled and has, one or more nuclei. Yeast, however, is single celled, and uninucleate.
- Their cell walls are made of chitin.
- They do not possess chlorophyll as their nutrition is by absorption or feeding on dead organic matter.
- Reproduction in fungi is both asexual by means of flagelalte or non-flagellate spores and sexual through conjugation
Fungi are eukaryotic, unicellular or multicellular saprotrophs having filaments which grow through soil, wood and other substrates.
Five main kinds of Fungi
The fungi are of five main kinds –
- Myxomycetes (मिक्सोमाइसेटिज), the Slime moulds, which have irregular shape.
- Phycomycetes, are unicellular, filamentous and branched e.g. Rhizopus and Phytophthora (फाइटोफ्थोरा)
- Ascomycetes, are one celled (e.g. yeasts) or multicellular branched e.g. Aspergillus, Penicillium, and Neurospora.
- Basidiomycetes (बेसिडियोमाइसेटिज), are multicellular, branched, and are represented by rusts, smuts, Mushrooms and toadstools, which are large enough to be seen by naked eyes.
- Deuteromycetes, are multicellular filamentous branched fungi which reproduce only by asexual means e.g. Alternaria.
- Lichens and mycorrhizae which exist in symbiotic associations.
Yeasts are fungi which do not produce any hyphae. These are generally in the form of single oval cells.
- ovoid cell.
- distinct cell wall and nucleus.
- one or more vacuoles in the cytoplasm.
- cytoplasm is granular and has glycogen and fat (oil) globules.
- Yeast is saprotrophic.
- Yeast respires anaerobically to yield energy.
- Yeast reproduces asexually by budding.
- Sexual reproduction may also occur by conjugation between two yeast cells.
Myxomycetes (Slime Moulds)
These consist of a naked, creeping multinucleate mass of protoplasm sometimes covering up to several square metres. The nuclei are diploid.
Basidiomycetes (Mushrooms and Toadstools)
The vegetative part of the mycelium lies embedded in the substratum (in ground or in wood) When conditions are favourable the umbrella like mushrooms grow out with a stalk and a cap.
These are a combination of a certain fungus and a green or blue green alga which live in a symbiotic (mutually beneficial) association : the green or blue green alga prepares food while the fungus gives protection, and absorbs water and minerals from the surroundings.
Economic importance of Fungi
A. Harmful Fungi
Several agricultural plants like sugarcane, maize, cereals and vegetables suffer from diseases caused by fungi.
1. Puccinia graminis (Wheat Rust):
- It causes brown patches on leaf and stem of wheat plants.
- It decreases the yield of wheat and makes it unfit for human consumption.
2. Rhizopus or (Bread Mould) grows on bread :
- If the bread is exposed to warm and humid conditions a cottony mass develops in few days.
- This white cotton mass later develops a greyish black colour, because of black coloured spores.
– The whitish network is called mycelium. (कवक-तंतु)
– The mycelium contains thread like structures called hyphae.
– The root-like sturctures growing out of the hyphae penetrate the bread, and secrete digestive enzymes (extra cellular digestion) and absorb the digested food.
– Greyish black colour of the mould develops due to formation of sporangium which after rupturing release dark coloured spores. The spores scatter by wind and germinate after falling on a suitable substractum. This is asexual reproduction.
Sexual reproduction takes place by conjugation between two neighbouring hyphae to produce a zygospore.
3. In human, skin diseases like ringworm and athlete’s foot are caused by fungi. Some ear infections are also caused by fungi.
B. Beneficial Fungi
- Certain Mushrooms (such as Agaricus campestris) are edible.
- Yeast is used for fermentation during manufacture of bread, beer, soya sauce, cheese and wine.
- Mycorrhizae are fungi associated with roots of plants. Roots benefit in getting minerals from the environment while fungi get food from the plant in return through such association.
- Neurospora has been a favourite experimental material in Genetics.
- Various antibiotics are derived from fungi. Penicillin is obtained from Penicillium notatum. Its antibiotic effect was discovered by chance by Alexander Flemming in 1927.
The Kingdoms Monera, Protista & Fungi : 12th Class Biology Question Answer
1. What is the chemical nature of the circular single chromosome of a bacterium?
2. Name the special region in the bacterial cell where genetic material lies.
3. What is the main component of cell wall in prokaryotes?
4. State one point of difference between flagella and pili.
Ans. Flagella are thicker and longer than pili / used in movement, used in conjugation.
5. Give one difference between aerobic and anaerobic bacteria
Ans. Aerobic bacteria respires in presence of oxygen / the anaerobic bacteria respires in the absence of oxygen.
6. What is transferred during sexual recombination in a bacterium?
Ans. A fragment of DNA strand.
1 Name the bacteria that :
(i) fix atmospheric nitrogen in the soil – Azotobacter
(ii) set milk into curd – Lactobacillus
(iii) cause tuberculosis – Mycobacterium tuberculosis
(vi) cause tetanus – Clostridium tetani
2. Approximately how many bacteria may be obtained from one bacterium in an hour?
3. Give any three differences between bacteria and cyanobacteria.
Bacteria – smaller cells, flagella present, sexual recombination by conjugation.
Cyanobacteria – large cells, no flagella, rare sexual recombination.
1. Protoctists are single celled like most of the Monerans. Why have they been put in a separate kingdom? Answer in one short sentence.
Ans. Protoctista are Eukaryotes / possess true nucleus.
2. Name the protozoan which causes
(i) Amoebic dysentery – Entamoeba histolytica
(ii) Malaria – Malarial parasite or Plasmodium.
3. Which is the kind of asexual reproduction found in Protoctista?
Ans. Binary fission
4. Through which organelle of the protoctists does respiration occur?
5. Name the organelle responsible for regulating water content (osmoregulation) in amoeba.
Ans. Contractile vacuole
6. Name two kinds of locomotion found in protoctista
Ans. Flagellar, Pseudopodial or amoeboid
1. Name the slender filaments that form the body of a fungus.
2. Which are the types of reproduction found in fungi?
Ans. asexually, sexually
3. Draw two small figures to show asexual reproduction in yeast.
4. Which are the four main kinds of fungi?
Ans. Yeast, Slime moulds, Mushrooms and Toadstools, Lichens
(i) the fungus from which Penicillin is extracted – Penicillium notatum
(ii) a unicellular fungus – Yeast
(iii) The fungus which causes wheat rust – Puccinia graminis
(iv) The whitish cottony mass, growing on stale bread – mycelium, Rhizopus
(v) Two common human diseases caused by fungi – Ringworm, Athelete’s foot
2. Who discovered antibiotic properties of Penicillium?
Ans. Alexander Flemming
I hope you liked this post (the living world). If you have any problem in understanding – The Kingdoms Monera, Protista & Fungi : 12th Class Biology Notes – NIOS, then write in the comment box below.
Be sure to subscribe to receive all new posts from this blog straight to your email inbox. Like my Facebook page to get notifications of similar posts on Facebook.
आपके द्वारा दी गई जानकारी काफी अच्छी है। मैंने आपकी वैबसाइट को बूकमार्क कर लिया है। हमे उम्मीद है की आप आगे भी ऐसी ही जानकारी देते रहेंगे।