11th Class

Anatomy : Study of internal structures of plants and animals after dissection.  Biochemistry : Study of chemistry of living matter (i.e., chemical composition, nature, mode of formation, functioning) in relation to life activities. Cytology :  Study of the structure and functions of cells and their organelles. Ecology : Study of relationship between organisms and environment. Embryology :  Study of developmental stages of organisms upto hatching or birth. Endocrinology : Study of endocrine glands and hormones action in animals. Evolution : Study of the origin of life and the gradual differentiation or descent of species. Histology : Study of tissues by microscopy. Immunology : Study of resistance of organisms to infection. Limnobiology : Study of fresh water lakes, ponds and streams. Morphology : Study of form and structure of animals. Palaeontology : Study of fossils and their distribution in time. Palaeozoology : Study of fossil animals. Physiology : Study of functions more...

Acarology : Study of mites and ticks. Actinobiology : Study of radiation effects on organisms. Aerobiology : Study of flying organisms. Agriology : Study of customs of primitive man. Algology : Study of algae. Anaesthesiology : Science for causing insensibility. Angiology : Study of blood vascular system including veins and arteries. Aphidology : Study of aphids (plant lice). Araneology : Study of spiders. Arthrology : Study of joints. Bryology : Study of mosses and liverworts. Carcinology : Study of crustaceans. Carcinology : Study of malignant tissue, tumor and cancer. Cardiology : Study of heart. Chondriology : Study of cartilage. Chorology : Study of the geographical distribution of organisms. Cnidology : Study of coelenterates. Conchology : Study of shells. Craniology : Study of skulls. Cryobiology : Study of effects on life at low temperature. Ctetology : Study of acquired characters of organisms. Dermatology : Study of body covering the skin. Ecobiology more...

It is a group of unicellular branched filamentous bacteria which resemble fungal mycelia. They grow in the form of radiating colonies in cultures and therefore, commonly called ray fungi. They are Gram +ve chemo-organotrophic, saprotrophic bacteria. Most species are facultative anaerobic. These are generally present as decomposers in soil. The filaments are aseptate (non-septate) branched and very thin (about 0.2 to 1.2 mm in width). The wall contains mycolic acid. They reproduce asexually by means of conidia, which are produced at tips of filaments. The endospores are not formed. Most of these secrete chemical substances having antimicrobial activities called antibiotics. Some of the most common and effective antibiotics are obtained from the different species of the genus streptomyces. Some species are pathogenic and cause diseases in plant, animal and human beings, e.g., Mycobacterium. Some common diseases in plants are yellow ear rot of wheat (Tundu disease) caused by Corynebacterium tritici more...

They are present in rumen (first part of stomach) of cattles. This is simplest and most primitive group of bacteria. The cell wall of these bacteria is made of polysaccharides and proteins (peptidoglycans and muramic acid are absent in cell wall). Further branched chain lipids are present in plasma membrane of archaebacteria, due to which these can face extremes of conditions of temperature and pH. Archaebacteria are considered to be 'oldest of living fossils'. Three main groups of archaebacteria are following. (1) Methanogens : These are strict anaerobic bacteria and mainly occur in muddy areas and also in stomach of cattle, where cellulose is fermented by microbes. These are responsible for methane gas \[(C{{H}_{4}})\] formation in bio-gas plants, because they have capacity to produce CH4 from CO2 or formic acid (HCOOH). e.g., Methanobacterium, Methanobacillus, Methanosarcina and Methanococcus. (2) Salt lovers archaebacteria or Halophiles : These are also anaerobic bacteria, which more...

Monera (Monos – single) includes prokaryotes and shows the following characters : (1) They are typically unicellular organisms (but one group is mycelial). (2) The genetic material is naked circular DNA, not enclose by nuclear envelope. (3) Ribosomes and simple chromatophores are the only subcellular organelles in the cytoplasm. The ribosomes are 70 S. Mitochondria, plastids, golgi apparatus, lysosomes, endoplasmic reticulum, centrosome, etc., are lacking. (4) Sap vacuoles do not occur. Instead, gas vacuole may be present. (5) The predominant mode of nutrition is absorptive but some groups are photosynthetic (holophytic) and chemosynthetic. (6) The organisms are non-motile or move by beating of simple flagella or by gliding. (7) Flagella, if present, are composed of many intertwined chains of a protein flagellin. They are not enclosed by any membrane and grow at the tip. (8) Moneran cells are microscopic (1 to few microns in length). (9) Most organisms bear a more...

(1) Many species of Nostoc fix atmospheric nitrogen and thus increases soil fertility. (2) Reclamation of alkaline usar soils can be done by employing some species of Nostoc. (3) N. commune is consumed as vegetable in China and Japan.

Cyanobacteria have both beneficial and harmful effects in human affairs. Useful activities (1) Growth of cyanobacteria in hard water is most probably responsible for the deposit of limestones. (2) Since they grow, photosynthesis, multiply and ultimately die, thus adding organic matter to the soil and increasing its fertility. (3) Whereas some cyanobacteria act to breakdown rock, the species that live in hot springs actually build rocks. This they accomplish by depositing salts of calcium and silica within the gelatinous sheath of the algal cell wall. (4) Balls of Nostoc commune are collected, boiled and consumed as food by the Chinese and South Americans. The prepared food is called 'Yoyucho'. (5) Some cyanobacteria, such as Anabaena, Lyngbya etc. help in conservation of soil, thus checking soil erosion. (6) Few species of Anabaena and Aulosira are inoculated in ponds to check the development of mosquito larvae. (7) Certain cyanobacteria like Nostoc commune, more...

Bacteria are our ‘friends and foes’ as they have both useful and harmful activities. Useful activities (1) In agriculture or In soil fertility : Some bacteria increase soil fertility. Nitrogen is essential for all plants. Nitrogen occupies 80% of the atmosphere. The plants take nitrogen in the form of nitrates. In soil, nitrates are formed by three processes : By nitrogen fixing bacteria : Bacteria are found in soil either free e.g., Azotobacter and Clostridium or in root nodules of leguminous plants e.g., Rhizobium leguminosarum. These bacteria are capable of converting atmospheric free nitrogen into nitrogenous compounds. Nitrifying bacteria : These bacteria convert nitrogen of ammonia into nitrite (NO2) e.g., nitrosomonas and convert nitrite compounds into nitrates e.g., nitrobacter. Decay of dead plants and animals : Some bacteria attack on dead bodies of plants and animals and convert their complex compounds into simpler substances e.g., carbon dioxide (CO2), water (H2O), more...

(1) Diseases in human beings : Mycoplamsa hominis causes pleuropneumonia, inflammation of genitals and endocarditis, etc. Mycoplasma pneumoniae causes primary a typical pneumonia (PAP), haemorrhagic laryngitis, etc. Mycoplasma fermentatus and M. hominis cause infertility in man, otitis media (inflamation of middle ear). (2) Diseases in animals : Mycoplasma mycoides causes pneumonia in cattle. Mycoplasma bovigenitalum, causes inflamination of genitals in animals. Mycoplamsa agalactia causes agalactia of sheep and goat. (3) Diseases in plants : Common mycoplasmal diseases of plants are: Bunchy top of papaya, witches' broom of legumes, yellow dwarf of tobacco, stripe disease of sugarcane, little leaf of brinjal, clover phylloidy, big bud of tomato etc. The new name of cyanobacteria has been given to myxophyceae or cyanophyceae. Cyanobacteria form a group of ancient Gram negative, photosynthetic prokaryotes. Many botanists prefer to call them blue-green algae. They have survived successfully for more...

On the basis of mode of nutrition, bacteria are grouped into two broad categories. First is autotrophic and second is heterotrophic bacteria.    Autotrophic bacteria : These bacteria are able to synthesize their own food from inorganic substances, as green plants do. Their carbon is derived from carbon dioxide. The hydrogen needed to reduce carbon to organic form comes from sources such as atmospheric \[{{H}_{2}},{{H}_{2}}S\] or \[N{{H}_{3}}.\]These are divided into two categories.   (1) Photoautotrophic bacteria : These bacteria are mostly anaerobic bacteria. They use sunlight as source of energy to synthesize food.  They possess a pigment called bacteriochlorophyll which is different from the chlorophyll pigment found in higher plants. This is known as anoxygenic photosynthesis. e.g., Green sulphur (Thiothrix) and purple sulphur (Chromatiun) bacteria. They can perform photosynthesis in far-red light. Rhodospirillum bacteria fixes \[C{{O}_{2}}\] into carbohydrate (Photoautotrophic).   Green sulphur bacteria : They are autotrophic. The hydrogen donor more...