Botanica: DESCRIPTION OF KINGDOMS

DESCRIPTION OF KINGDOMS

1. kingdom Monera- The kingdom includes all unicellular prokaryotes- mycoplasma, bacteria, and cyanobacteria.

Cell type ---------------- prokaryotic.

Thallus organization------- unicellular.

Cell wall----- present (peptidoglycan or murein)

Nuclear membrane ----- absent.

Nutrition ------- autotrophic, heterotrophic, chemosynthetic

Reproduction--------asexual and by genetic transformation, transduction, and conjugation.

General characters’;

Unicellular, prokaryotes and contain the most primitive of living forms.
The cells are microscopic and cell wall is generally present.
Cell shape may be spherical (cocci), rod shaped (bacilli), comma shaped (vibrio) spiral (spirilla)
Genetic materials are not organized into nucleus and contain naked DNA.
Membrane bounded organelles are absent.
Reproduction is asexual (by binary fission, multiple fission, budding etc.)
Sexual reproduction occurs by genetic transformation, transduction, and conjugation. Sexual organs are absent.
cell surface appendages include long Flagella (motility) pilli-for conjugation (1-10 per cell) and fimbriae-for cell surface attachment (more than 100 per cell)
Example- Blue-green algae, Bacteria etc.
Bacteria are the most abundant micro-organism that can survive in all kinds of climate. The bacteria are divided into following groups;

Archaeobacteria – They constitute the group of most primitive prokaryotes which live under most hostile conditions like extreme salty area (halophiles), hot springs (thermophiles) and in marshy areas (methanogens). They differ from other bacteria in having different call wall structure (muramic acid). Methanogens are present in the gut of several ruminant animals like cows and buffalo, which is responsible for production of biogas (methane) from dung of these animals.

Eubacteria – They are called as true bacteria and contain rigid cell wall, if motile contain flagellum. Chemosynthetic bacteria oxidize inorganic substances like nitrate, nitrite, ammonia etc. to produce energy and help in recycling of nitrogen, phosphorous, sulphur etc. Heterotrophic bacteria are most abundant and act as decomposer.

Mycoplasma – they are the simplest free living prokaryotes. They are also known as PPLO (Pleuro-pneumonia like organisms). They lack cell wall and can survive without oxygen.

ECONOMIC IMPORTANCE OF BACTERIA

Bacteria (Methanogens) are responsible for production of biogas.
Chemosynthetic bacteria oxidize inorganic substances like nitrate, nitrite, ammonia etc. to produce energy and help in recycling of nitrogen, phosphorous, sulphur etc
Heterotrophic bacteria are most abundant and act as decomposer.
In industry bacteria are used for the production of curd (lactobacillus bulgarius) Butter (Streptococcus lactus) vinegar (Acetobactor).
Bacteria fix atmospheric nitrogen in leguminous plants. Azobacter (free living) and Rhizobium species (symbiotic)
Bacteria are also used for the production of many vitamins, vaccines, enzymes and antibiotics. E.g streptomycin (Streptomycis griseus), tetracycline (S. auefaciens) erythromycin (S. erythrius).

2. kingdom Protista- Kingdom Protista includes Chrysophytes, Dinoflagellates, Eugleoids, slime moulds and Protozoans.

Cell type ------------------ eukaryotic.

Thallus organization------- unicellular.

Cell wall ------------ present in some.

Nuclear membrane --------- present.

Nutrition ------------ autotrophic, heterotrophic.

Reproduction ------------ asexual and sexual.

General charecters;

Protista include all unicellular and colonial eukaryotes.
Most of them are aquatic forming plankton.
Mode of nutrition may be photosynthetic, saprobic, parasitic or holozoic.
Flagella if present are double stranded with 9+2 arrangement of microtubules composed of tubulin.
Genetic material consists of 2 or more DNA molecules.

Chrysophytes;-

They include diatoms and golden algae (desmids) found in fresh water as well as in marine water.
In diatoms cell wall forms two thin overlapping cells which fit together as in soap box.
They contain siliceous indestructible cell wall

These pile up at the bottom of water reservoirs and form big heaps called diatomaceous earth. They are chief producer in oceans.

Dinoflagellates

They are basically unicellular motile, biflagellate and photosynthetic protists.
Predominant colour is golden brown but are yellow, green, red and even blue.
Some Dinoflagellates like Gymnodinium and Gonyaulax grow in large number in the sea and make the water look red and cause the so called “red tide”.

Eugleoids

They are Euglena like unicellular flagellates which possess pellicle instead of cell wall which makes their body flexible.
They have two flagella, one short and other long.
They are photosynthetic in presence of sunlight and heterotrophic in absence of sunlight.
Example- Euglena, Peranema.

Slime Moulds

They are saprophytic protists and feeds on decaying twinges and leaves.
Under favorable condition, they form an aggregation called plasmodium which produce fruiting bodies bearing spores.
The cell wall of spores bears cellulose.
Example- Physarum, Fuligo.

Protozoans

All protozoans are heterotrophs and live as predators of parasites.
They are considered as primitive relatives of animals.
Amoeboids move and capture food by pseudopodia. Some are parasitic also.
Flagellated protozoan’s are free-living or parasitic. They have flagella.
Ciliated protozoan’s are aquatic and have cilia all over the body for movement.
Sporozoans includes organism that have infectious spore like stage in their life cycle.

3. Kingdom Fungi – fungi are achlorophyllous, heterotrophic, spore forming, non-vesicular eukaryotic organisms.

Cell type -------------------- eukaryotic.

Thallus organization----------multicellular.

Cell wall ------------- present (chitin).

Nuclear membrane --------- present.

Nutrition ---- heterotrophic, saprophytic, parasitic or symbiotic.

Reproduction ------ asexual as well as sexual.

General characters’;

All fungi are multicellular except yeast ( unicellular)
Body is made up of small thread like structures called hyphae. The network of hyphae is called mycelium.
Cell wall is made up of chitin (fungal cellulose in yeast).
Reserved food material is glycogen.
Mode of nutrition is saprophytic, parasitic or symbiotic.
Reproduction may be vegetative (fragmentation, fission or budding), asexual (conidia, sporangiospores or zoospores) or sexual reproduction by oospores, ascospore and basidiospores.sex organs are also called as the fruitning bodies.

Sexual cycles involves the following steps-

(a) Plasmogamy, fusion of male and female gametes.

(b) Karyogamy, fusion of two nuclei.

Sexual reproduction occurs by many methods such as;

Isogamy; it involves fusion of two similar gametes.

Anisogamy; it involves fusion of two dissimilar gametes like larger egg and smaller male gamete

Oogamy; it involves fusion of large non-motile egg and small motile anthrozoid.

Gametangial contact; - it involves sideway fusion of two gametangia, oogonium and antheridium. (phytopthora)

Gametangial copulation; it involves head to head fusion of two similar gametes to form a zygospore. (Rhizopus).

(a) Phycomycetes-

These are found in aquatic habitat and on decaying wood, in moist and damp places.
The mycelium is aseptate and coenocytic.
Asexual reproduction occurs by zoospores (motile) or aplanospores (non-motile).
Example- Mucus, Rhizopus, Albugo etc

(b) Ascomycetes (The sac fungi)

They are saprophytic, decomposers, parasitic or coprophilous (growing on dung).
Mycelium is branched and septate
Asexual spores are conidia.
Sexual spores are called ascospores produced inside the fruiting body called ascocarps.
Example- Neurospora, Asperigillus, Claviceps etc.

The mycelium is branched and septate.
Vegetative reproduction is by fragmentation.
Asexual spores are not found.
Sexual reproduction occurs by two vegetative or somatic cells forming basidium.
Basidiospores are produced in basidium by developing a fruiting body called basidiocarps.
Example- Agaricus, Ustilago, Puccinia.