Posts

Characteristics of Fungi

General characters 1. Constitute a unique kingdom of heterotrophic organisms. 2. Show great diversity in morphology and habitat. 3. Some are parasitic while most are saprophytic(fed on dead organisms). 4. Except Yeasts(Unicellular), other are multicellular and filamentous. 5. The body consists of long, slender, thread like structures called hyphae and network of hyphae is known as mycelium. 6. Some hyphae are continuous and multinucleate known as coenocytic hyphae while others have septate(have cross wall). 7. Cell wall is composed of chitin and polysaccharides. 8. Shows symbiotic association with algae called lichen and with roots of higher plants known as mycorrhiza. 8. Vegetative reproduction takes place by fragmentation, fission, budding, Asexual by spores called conidia, zoospores, aplanospores, etc. and sexual reproduction takes place by forming oospores, ascospores and basidiospores. 9. Sexual reproduction involves fallowing. a) Plasmogamy- Fusion of protoplasm of two gametes b)

economic importance of cyanobacteria

Cyanobacteria(Blue-green algae) are both useful and harmful to mankind. . Their economic importance are as fallows. 1) Algal Nuisance in Water Supplies The extensive growth of blue green algae create serious problems in the maintenance of water supplies, particularly in low land water reservoirs. They implode the routine filtration procedure essential in the provision potable water. They may rapidly clog not only the fine sand filters but even the fast filters. In addition to this, these also produce bad smell and secrete toxic substances to drinking water. The mass appearance of blue green algae has also a distinctive effect upon recreational activities like swimming, sailing or fishing in lakes and reservoirs. 2) Toxic Blue green algae Several examples of poisoning of farm animals due to the ingestion by drinking animals of lethal doses of toxic blue greens like Microcystis aeruginosa. Some toxic substances like microcystin, anatoxin, saxitoxin etc. have been isolated and identified.

Characteristics of Kingdom Protista

1. They include all single celled eukaryotes. 2. They contain membrane bound cell organelles. 3. They possess well defined nucleus. 4. They have a cellular level of body organization. 5. They reproduce sexually and asexually. 6. Their mode of nutrition is autotrophic and heterotrophic. 7. They move across the environment using  8. Flagella, cilia, pseudopodia, or propulsion by contraction of the body and mucilage are the most significant forms of locomotory organelles present in them. Fallowing are the members of the kingdom Protista 1. Chrysophytes(Planktons) a) Includes diatoms and golden algae(desmids). b) Found in fresh water as well as marine environments. c) Microscopic; float passively in water currents. d) Mostly photosynthetic. e) cell wall forms two thin overlapping shells. f) Walls embedded with silica, and thus, indestructible. g)Fossilized remains of diatoms are referred to as 'diatomaceous earth'. h)They are the chief producer of the ocean. 2. Dinoflagellates a) M

characteristics of kingdom Monera

General characters 1. They are most abundant microorganisms 2. They occur almost everywhere including extreme environments such as hot springs, deep oceans, snow and deserts. 3. Bacteria are the sole member of the kingdom Monera 4. Many live in or on other organisms as parasites 5. Cell structure is very simple but complex in behavior. 6. Show the most extensive metabolic diversity some are Autotrophic(Photosynthetic- use carbon dioxide and water and Heterotrophic(Use inorganic substance like nitrogen, Sulphur, iron etc.) Classification of Bacteria i) Monera includes unicellular(single celled) organisms. ii) They are prokaryotes. Their chromosome material is not organized into nucleus. It lies directly inside the cytoplasm and is called nucleoid. iii) Membrane bound cell organelles like mitochondria, Golgi apparatus, lysosomes etc. are absent iv) Cell wall may or may not be present. v) Mode of nutrition. Classification of bacteria based on shape; Spherical shape(Cocci) Ex: Staphylococc

Biological classification of organisms

Classification is the arrangement of organisms in specific groups or categories based on certain characters. System of classification 1) Artificial system: In this system, morphological characters like habit, habitat, number of stamens etc. are considered to classify organisms e.g.: Linnaean system 2) Natural system: In this system, natural relationship are considered to classify organisms Ex: George Bentham and Joseph Dalton Hooker's system 3) Phylogenetic system: In this system, evolutionary relationships are taken into account to classify the organisms. e.g.: Engler and Prantl's system. Aristotle was the earliest to attempt a more scientific bases for classification. He used simple characters like morphology to classify the plants into herbs, shrubs and trees. He also divided animals into two groups, those which had red blood and those did not. Two kingdom system of classification Proposed by C. Linnaeus He divided organisms into two kingdoms-Plantae and Animalia. Demerits:

Stages in the development of plant disease

The term disease cycle is used to describe the relationship between pathogen and host. The events in a disease cycle involve the survival of pathogen during periods that are not favorable for disease development, inoculation, penetration, establishment of infection, colonization, growth and reproduction of the pathogen, and over seasoning of the pathogen. Inoculation The process whereby a pathogen comes in contact with the host is called inoculation. Inoculation include fallowing things. i) The inoculum: It is a sample of microbes that can initiate infection. ii) The source of inoculum: It consists of the plant debris or soil on which the inoculum has over seasoned. Some times it comes from infected parts of the crop or plant. iii) Inoculum dispersal: Inoculum are usually disseminated by wind, water, soil, plant parts or by a vectors, some times human beings. a) Dissemination by wind: The spores of many pathogens are disseminated by the wind. sometimes, the diseased plant parts help di