How the classification systems have undergone several changes over time?
- The earliest classification was based on usage of organisms such as food, shelter and clothing.
- Aristotle divided plants into herbs, shrubs and trees; and divided animals into red blooded and non red blooded.
- Linnaeus introduced a 2-Kingdom classification system - Kingdom Plantae and Kingdom Animalia on the basis of presence of cell wall.
- R.H. Whittaker in 1969 introduced a 5-Kingdom classification system. (K. Monera, K. Protista, K. Fungi, K. Plantae and K. Animalia)
- Carl Woese introduced a 3 - Domain system.
What were the criteria on which Whittaker divided organisms into 5 kingdoms?
- Cell structure
- Body organisation
- Phylogenetic relationships
- Mode of nutrition
- Mode of reproduction
Who are the members of Kingdom Monera?
Write about their characteristics: -
1. Where are they found?
2. Where do they live?
3. Classification?
4. Structure and behaviour?
5. Mode of nutrition?
6. Mode of reproduction?
7. Diverse in what?
Bacteria are the sole members of Kingdom Monera.
- They are found almost everywhere. (Ubiquitous)
- They live in extreme conditions such as deep oceans, hot springs, snow, desert, etc.
- They are classified on the basis of their shape:-
~ Coccus (spherical shape)
~ Bacillus (rod shape)
~ Spirillum (spiral shape)
~ Vibrium (comma shape) - They have simple structure but a complex behaviour
- They can be autotrophic and heterotrophic
- They reproduce by asexual, sexual and vegetative means.
- They show extensive metabolic diversity.
Write a note on Archaebacteria.
- They live in extreme conditions.
(i) Halophiles - in extreme salty areas
(ii) Thermoacidophiles - in extreme hot area
(iii) Methanogens - in marshy areas as well as in the gut of ruminant animals such as cow and buffalo
used to make methane (biogas) from the dung of these animals.
- They can live in such extreme conditions because of a different cell wall structure.
Write a note on cyanobacteria.
- Also called as blue - green algae.
- It is autotrophic (photosynthetic).
- It has a pigment chlorophyll a in it.
- It can be filamentous or colonial or unicellular.
Colonial bacteria - ex. Nostoc which have specialised cells for nitrogen fixation called Heterocyst and are covered by mucilagenous sheath. - Found in marine or fresh or polluted water as well as terrestrial.
Write a note on Heterotrophic bacteria.
- It is Heterotrophic in nature.
- Used for curd formation, nitrogen fixation and antibiotic production.
- Causes disease such as cholera, citrus canker, typhoid, tetanus, etc.
- Reproduce sexually as wall as asexually.
Write a note on Mycoplasma.
- Smallest living cell present on earth.
- Can pass bacteria proof filter.
- Pathogenic in plants and animals.
- Lack of cell wall.
- Can survive without oxygen.
Who are the members of Kingdom Protista?
Write about their characteristics.
All unicellular eukaryotic organisms are found in K. Protista.
- Nucleus and organelles present.
- Flagella or cilia present.
- Boundaries are not defined.
- Reproduce sexually as well as asexually.
- Mainly aquatic.
Write a note on Chrysophytes.
- They belong to K. Protista.
- Ex. Diatoms and Desmids ( golden algae).
- Diatoms have overlapping silica cell walls like a soap box which make it indestructible.
- Form diatomaceous earth bcz their cell wall can’t be destructed easily.
- Chief producers in the oceans.
- Float passively on water.
- Being gritty, they are used for polishing and filtering oils and syrups.
Write a note on Dinoflagellates.
- Belong to K. Protista.
- They are colourful due to pigments. (Green, blue, red, yellow and brown).
- photo autotrophic
- Have two flagella ~ One transversally and one longitudinally.
Red Dinoflagellates
- ex. Gonyaulax
- Release harmful toxins
- form red tides bcz of rapid multiplication.
Write a note on euglenoids.
- Belong to K. Protista.
- have two flagella ~ One longer for locomotion and one shorter.
- can be Autotrophic and Heterotrophic.
- have a pigment that is found in higher plants.
- Ex. Euglena
- Have a protien rich flexible layer called pellicle instead of cell wall.
Write a note on slime moulds.
- Belong to K. Protista.
- Saprotrophic
- Form plasmodium under favourable conditions.
- Form spores at the tip of the fruiting bodies under unfavourable conditions.
- Those spores have true cell walls and are dispersed by air.
Write a note on Protozoa.
- Belong to K. Protista.
- Heterotrophic
- Primitive relatives of animals.
- Classified into four categories
- Amoeboid P. - have pseudopodia
Ex. Entamoeba
Found in marine and fresh water as well as moist soil.
Have silica shell. - Flagellated P.
Have flagella present
Free living
Parasitic
Ex. Trypanosoma which causes sleeping sickness. - Ciliated P.
Have cilia
Ex. Paramecium
Have gullet - Sporozoans
Have infectious spores
Ex. Plasmodium which causes malaria.
Write about the characteristics of the organisms that belong to Kingdom Fungi.
- Where are they found?
- Mode of nutrition?
- Mode of reproduction?
- Grow where?
- Cell structure?
- They are found almost everywhere.
- Heterotrophic - Saprotrophic, parasitic or symbiotic.
- Reproduce sexually as well as asexually and vegetatively.
- Grow in moist and humid climate.
- Mainly multicellular except yeast.
They are cosmopolitan.
Define the following terms.
- Hyphae
- Mycelium
- Coenocytic mycelium
- Long thread like structures present on the body of fungi are called hyphae.
- A network of hyphae is called mycelium.
- A continuous tube like structure with multinucleated cytoplasm is called a coenocytic mycelium.
What are the spores produced in the
- asexual reproduction of fungi.
- Sexual reproduction of fungi.
- Asexual spores
- Conidia
- Zoospore
- Sporangiospore - Sexual spores
- Bascidiospore
- Oospore
- Ascospore
Write the steps of sexual reproduction in fungi.
- Plasmogamy - Fusion of two protoplasm.
- Karyogamy - Fusion of two nuclei.
- Meiosis - formation of diploid spores.
Sometimes the diploid spores don’t want to separate, hence, they form a condition of (n+n) which is called dikaryon and this phase is called dikaryon phase.
What is the basis of classification of fungi?
- Morphology of mycelium
- Mode of spore formation
- Fruiting bodies
Write a note on Phycomycetes.
- Mycelium?
- Reproduction? Spores?
- Where are they found?
- Examples?
- Mycelium is aseptate and coenocytic.
- Reproduce through asexual spores- zoospore (motile) and aplanospore (non - motile).
sexual spores - zygospore - Found in water, decaying wood and as parasites.
- Mucor, Rhizopus and Albugo
Write a note on Basidiomycetes.
- Mycelium?
- Reproduction? Spores?
- Where are they found?
- Examples?
- Nutrition?
- Mycelium is branched and septate.
- Reproduce through sexual spores called basidiospore (exogenously produced) which are formed in fruiting bodies called basidiocarps.
- Found in wood stumps, logs and soil.
- Puccinia, Ustilago and Agaricus
- Saprophytic
No asexual reproduction.
Write a note on Ascomycetes.
- Mycelium?
- Reproduction? Spores?
- Examples?
- Nutrition?
- Also known as?
- One more feature?
- Mycelium is branched and septate.
- Reproduce through asexual spore - Conidia (exogenously produced) and sexual spore - Ascospore (endogenously produced).
- Neurospora (used in genetics),
Penicillium, Yeast, Aspergilla, Claviceps. - Also known as sac - fungi.
- It is coprophillous (found on dung of animals).
Write a note on Deuteromycetes.
- Mycelium?
- Reproduction? Spores?
- Examples?
- Nutrition?
- Also known as? and Why?
- Mycelium is branched and septate.
- Reproduce through asexual spore - Conidia and by vegetative means.
- Trichoderma, Alternaria and Colletotrichum.
- Saprotrophic, parasitic and decomposers.
- Also known as Imperfect fungi because sexual reproduction is not known.
Write a brief note on the genetic material of viruses.
- Genetic material of viruses is infectious and contains proteins.
- It can contain either RNA or DNA, not both.
- It has a protective layer called Capsid which protects the nucleic acid.
~ in plants, the viruses contains only single stranded RNA
~ in animals, the viruses can contain both single and double stranded RNA or DNA.
~ in bacteria, they contain double stranded DNA.
The viruses that infect bacteria are called Bacteriophages.
Write the contributions of the following in the terms of viruses: -
- Dmitri Iwanowasky
- MW Beijerinek
- WN Stanley
- He recognised certain microbes which were smaller than bacteria in tobacco mosaic disease in 1892.
- He named those microbes as viruses.
Extracted a fluid called Contagium Vivum Fluidium (Infectious Living Fluid) from a healthy plant. - He said that viruses can be crystallined, they are obligate parasites and are inert outside.
