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Saturday, September 25, 2010

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Effect of Pollution and its Control

air pollution pollutant

Air Pollution
Dry air has 78% N2, 21% O2, 0.03% CO2 and the rest other gases are about 1%. Air pollution is principally caused by man. Due to human activities, the amount of solid waste or concentration of gases other than O2 increase in the air and disturb the natural composition of air. This phenomenon is referred to as air pollution. Air pollution is one of the most dangerous and common kind of environmental pollution that is reported in most industrial towns and metropolitans. Motor vehicles are the major problems of the world which cause air pollution.

Friday, September 24, 2010

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Mountains and Nepal

Mountain is a topographical feature that rises more than 300m above the surrounding. There is a difference between mountain and hill. Hill is a land surface lower than a mountain that rises prominently above the surrounding lands to elevations less than 300 m. This region is represented by Siwalik and Mahabharat rmount everest north face mountain himalayaange in Nepal. Mountain environment is of great importance in Nepal. Nepal is predominantly a mountainous country. The Himalaya extends over a length of approximately 2400 km from the Indus to the Brahmputra. The central sector of Himalaya about 800 km lies in the kingdom of Nepal. The hills and the Himalayas constitute over 78% of the total geographical area of Nepal (145,305 sq. km.). Nepal justifies its position as elevationally highest country in the world with average altitude of 4500 m, and most of majestic peaks of the world are located here.

Monday, September 20, 2010

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Frog (Rana tigrina)

rana tigrina diagram frog

Frog is an amphibian, living both on land and in water. The amphibians are the first group among the chordates that live outside water. But the amphibian is still chained to water, in water it is born, to water it must periodically return for respiration. They are cold-blooded vertebrates having two pairs of limbs- tetrapods. They have smooth and moist skin. Rana tigrina is studied in detail because of its easy availability and its structural details have very common features to other animals.

Phylum: Chordata
Subphylum: Gnathostomata
Superclass: Tetrapoda
Class: Amphibia
Order: Anura
Genus: Rana
Species: tigrina

Friday, September 17, 2010

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Plasmodium ( The Malarial Parasite)

Plasmodium is the best known protozoan parasite of man, which causes malaria. malaria is one of the widespread tropical diseases among human being. About one-third of the entire population of many hot countries suffer from it every year. It is a serious economic and social problem as it causes deaths and affects majority of population. It is responsible for persistent sickness, loss of working ability and slowing down of mental and physical development among children. In 1943, Russel estimated that there were three hundred million cases of malaria in the world. In 1957 it was estimated that more than 200,000,000 (about 10 percent) of world population had malaria of grater or lesser severity. A significant role was played by malaria in military history. It has decided the fates of many army men. There are several examples of army man being defeated by malaria instead of enemies. During the war of 1914-18, malaria caused death of several army men. Among British troops there were 160,000 admissions of malaria cases to hospitals in Macedonia; 35,000 in Egypt; 107,000 in East Africa and 120,000 in Mesopotamia. Due to large number of patients suffering from malaria all soldiers did not receive treatment in hospitals. During 1918 the british forces in Macedonia alone lost 2,000,000 during service days.
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Functional Aspects of Ecosystem

The functional aspects of ecosystem include the flow of energy and the cycling of nutrients. Inorganic compounds are synthesized into organic structure by the green plants through photosynthesis and solar energy is utilized in this process. Energy enters the ecosystem, when the producers build organic compounds during photosynthesis. The green plants (producers) fix solar energy and with the help of inorganic substances such as carbon dioxide and water taken from soil and aerial environment they build up complex organic matter. The organic matters are carbohydrate, fat, protein, etc. From green plants these organic foods are passed on to the herbivores, which in turn become source of energy for the carnivores. Thus, the animals are known as consumers. All the living organisms whether plants or animals in an ecosystem have a definite life span after which they die. The dead organic body of plants and animals provide food for saprophytic microbes, such as bacteria and fungi. These microbes are known as decomposers, which ultimately decompose the dead organic body into simple organic components into their environment. During the process of decomposition the energy is lost in the form of heat into the environment. Thus in an ecosystem, energy flows in a non-cyclic manner (unidirectional) from the sun to the decomposers via producers and consumers (herbivores and carnivores), whereas the minerals keep on moving in a cyclic manner. Minerals are withdrawn from the substrata, deposited in the tissues of plants and animals, cycled from one feeding group to another, return to the soil, water and air then recycled. These two ecological processes of energy flow and mineral cycling which involve interaction between biotic and abiotic components may be thought as the 'heart' of the ecosystem dynamics.

Wednesday, September 15, 2010

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Factors of Ecosystem [Part 2]

Topographic Factors (Physiographic Factors): Topographic factors include height, direction and the steepness of slope.
1) Height or Altitude: Higher altitude ecology flag tree(mountains, hills, etc.) is characterised by low temperature, high velocity of wind, lower atmospheric pressure, high humidity and rainfall. The temperature decreases with the increase of height and the lower temperature favour the formation of clouds and rain. Thus, the mountains and hills are favourable for plant growth and causes different types of forest due to above climatic variations. However, at very high hills and mountains the water vapours directly condense into snow and cause poor vegetation.
2) Direction of the Slope: It is generally observed that the sunward direction of the slope is warmer compared to the opposite, because, the duration of sunlight is longest in sunward direction. It also gets good rainfall. Thus, the sunward directed slope possesses good vegetation whereas the vegetation is poor on the opposite direction due to little or no direct solar radiations.
3) Steepness of the Slope: The steepness of the slope allows rapid flow of rain water and causes water deficit. The rapid movement of water over the slopes cause erosion of the top soil and thus the vegetation disappears from the area. On the other hand plain soil surface sloe the water movement and allows to soak in the soil. It also receives sunlight for long duration. thus the less steepy area is best suitable for plant growth.
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Factors of Ecosystem [Part 1]

ecosystemEvery living organism is surrounded by materials and forces which constitutes its environment and from which it must derive its needs. Any external force, substance or condition which surrounds and affects the life of an organism in any way is referred to as environmental factor or ecological factor. These factors are living as well as non-living. The living factor is called the biotic factor and non-living is called the abiotic factor. Thus, the ecosystem is governed by two environmental factors (components) biotic factors and abiotic factors. These factors determine the quality and the viability of the ecosystem.

Tuesday, September 14, 2010

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Reproductive System of Earthworm

Earthworms reproduce sexually. They cannot reproduce asreproductive system earthworm pheretima posthumaexually. They are hermaphrodite (monoecious) i.e. both ovaries and testes are found in the same individual. They are protandrous, the male sex cells mature much earlier than the female cells, therefore, self-fertilization is not possible. The relative position of ovary and testes also makes self-fertilization impossible. Cross-fertilization is preceded by copulation and cocoon formation.

Male Reproductive Organs:
The male reproductive organ comprises testes, testis sacs, seminal vesicle, vasa deferentia, Prostate gland and accessory glands.
Testes: The earthworm contains two pairs of testes, one pair in the 10th and the other pair in 11th segments found attached with the posterior surface of 9/10 and 10/11 intersegmental septa. They are found ventro-laterally beneath the alimentary canal on either side of the nerve cord.