DEFINITION
- Habitat - Monerans are found everywhere in hot springs, under ice, in deep ocean floor, in deserts and on or inside the body of plants and animals.
- Nutrition - Autotrophs, heterotrophs, parasitic, symbiotic, commensalism, mutualism.
- Respiration in these organisms vary, they may be obligate aerobes, obligate anaerobes and facultative anaerobes.
- Circulation is through diffusion.
- Movement is with the help of flagella.
- Reproduction is mostly asexual, sexual reproduction is also seen. Asexual reproduction is by binary fission, sexual reproduction is by conjugation, transformation and transduction.
- Photosynthetic Protists: They include dinoflagellates, chrysophytes and euglenoids.
- Slime moulds
- Protozoan Protists: They include flagellated protozoans, amoeboid protozoan, sporozoans and ciliated protozoans.
- Most of them are marine but some occur in fresh water.
- Some show bioluminescence.
- Nutrition is photosynthetic.
- For example, Glenodinium.
- They include diatoms and desmids.
- For example, Spirogyra, Cymbella.
- Occur in fresh water and damp soils.
- Nutrition is holophytic.
- For example, Euglena, Phacus.
Benefits of Protozoa:
a) They are useful for cleaning of dirty water by the process of decomposition.
b) They are useful in scientific research.
c) They are useful in the food chain and especially used as a food for animals.
Non-green, unicellular/multicellular, eukaryotic, heterotrophic and saprophytic organisms.
Has the presence of cell wall which is made up of chitin.
Most of them are made up of thread like hyphae rather than cells.
Reproduction in fungi is both by sexual and asexual means.
For example, yeast, moulds, mushrooms. Most common moulds (fungi) are Aspergillus and Penicillium.
Oomycetes
- The mycelium is coenocytic.
- Asexual reproduction involves formation of spore containing sacs.
- Gametes are usually nonflagellate.
- Sexual reproduction is by gametangial contact.
- For example, Phytophthora, Albugo.
The fungal group Zygomycota is most frequently encountered as common bread molds, although both freshwater and marine species exist.
Most of these live on decaying plant and animal matter found on the substrate.
They are usually recognized by their profuse, rapidly growing hyphae, but some exhibit a unicellular, yeast-like form of growth.
Asexual reproduction is by means of spores produced in sporangia borne on the hyphae.
For example, Mucor, Rhizopus (the bread mould) and Pilobolus.
The sac-fungi produce spores in small cup-shaped sacs called asci, hence the name ascomycota.
The mature sac fungi spores are known as ascospores, they are released at the tip of the ascus breaks open.
Yeast is the most common one-celled fungi. Yeast reproduces through asexual process called budding. The buds form at the side of the parent cell, they pinch-off and grow into new yeast cell which is identical to the parent cell.
For example, Aspergillus, Claviceps, Neurospora.
The fungal group Basidiomycota, also known as the club fungi, includes some of the most familiar fungi.
Basidiomycetes play a key role in the environment as decomposers of plant litter. They are distinguished from other fungi by their production of basidiospores, which are borne outside a club-shaped, spore-producing structure called a basidium. These spores rarely germinate or mature.
For example, Agaricus (mushroom), Ustilago (smut), and Puccinia (rust fungus).
Their lack of sexual stages was the basis for them being called fungi imperfecti in the past.
Most Deuteromycota have only asexual reproduction as the sexual stage of the life cycle has been lost or has yet to be discovered.
There are a great number of human uses for these fungi; most significant is the production of antibiotics for medicinal use. These substances are produced by the fungus to inhibit the growth of other living organisms around themin particular, disease-causing bacteria. These substances are extracted from the fungus and are used to kill bacteria in the human body.
Economically important imperfect fungi are Penicillium and Aspergillus.
- Zoospores
- Sporangiospores
- Chlamydospores
- Oidia
- Conidia
- Ascospores
- Basidiospores
- Binucleate spores
Cryptogamae
- Thallophyta is the plants which are aquatic and cannot survive on land because of undeveloped root and stem. For example, algae.
- Bryophyta is the plants which can survive on both land and water. For example, Moss.
- Pteridophyta is the plants which can survive on land as they have well-developed root and stem. For example, Ferns.
- Gymnosperm is the plants with naked seeds. they are evergreen and woody. For example, cycas.
- Angiosperms are the plants which are fully modified flowering plants. They are further divided into monocot and dicot. Monocots have seeds with one cotyledon and dicot has seeds with two cotyledons. For example - mango
Invertebrates:
Invertebrates are smaller in size and further classified into six groups.
1) Molluscs- They have a soft unsegmented body, found on both land and water. Example are snail, clam, oyster etc.
2) Worms- Animals that lack legs are called worms. some have segment body and some do not. Example are earthworm, flatworm etc.
3) Arthropods- They possess jointed legs, a tough exoskeleton. This is the largest group of invertebrates. Examples are insects, millipedes, centipedes etc.
4) Porifera- They are mostly marine and have a porous body through which exchange of food and gases takes place e.g., sponge.
5) Cnidaria- They are marine animal and possess a sac-like body with a single opening (mouth) e.g., hydra, jellyfish etc.
6) Echinoderms- Aminals with spiny skin are called echinoderms such as starfish, sea urchin etc.
Vertebrates:
Vertebrates possess vertebral column. They are further classified into five groups. 1) Pisces- An aquatic animal with a streamlined body, covered with scales e.g., fishes.2) Amphibia- Animal that can live in water as well as on land and breathe through both lungs and gills e.g., frog.3) Reptilia- Animals that can crawl are called reptiles. They possess dry and scaly skin e.g., snakes.4) Aves- Animals that can fly and have hollow and light bone e.g., sparrow, parrot etc.5) Mammals- Animals that possess mammary glands are called mammals and give birth to young ones e.g., cow, dog deer etc.
- All plant viruses have single-stranded RNA
- Animal viruses have single or rarely double-stranded RNA or double-stranded DNA, and
- Bacterial viruses (bacteriophages) contain mostly double-stranded DNA but can also have single stranded DNA or RNA.
| Viruses | Bacteria |
| Very small (visible only by electron microscope) | Larger (can be seen by light microscope) |
| Non-cellular. | Single-celled. |
| Have no metabolism. | Have metabolism. |
| Neither grow nor divide. | Grow in size and divide to produce more bacteria. |
| Can be crystallized. | Cannot be crystallized. |
| Command the host cell to produce virus. | Self reproduce. |
| All produce disease in man, animal and plants. | Some harmless, some useful and some disease producing. |
- Viriods are small single-stranded circular RNA agents which infect plants.
- They differ from RNA viruses in three major aspects: their minute size (they are non-quarter of the size of the smallest RNA virus, i.e., 250-400 bases); the genome does not encode any proteins and they are not encapsidated.
- Viroid infections is mediated mechanically.
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