Effect of Pollution and its Control

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.

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Shirish 11:37 PM   No comment

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 range 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.

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Frog (Rana tigrina)

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.

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

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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.

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Shirish 1:44 AM   1 comment

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 (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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Shirish 11:47 PM   No comment

Factors of Ecosystem [Part 1]

Every 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.

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Reproductive System of Earthworm

Earthworms reproduce sexually. They cannot reproduce asexually. 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.

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Shirish 2:12 AM   2 comments

Earthworm [Part 2]

5) Locomotion:
Locomotion in earthworm is caused by setae and the musculature of the body wall. When as earthworm starts to crawl, the first few segments become thinner and extend forward. This is due to contraction of the circular muscle fibres and relaxation of the longitudinal muscles in that region. The longitudinal muscles of the anterior segments now contract and the circular muscles relaxes due to which anterior end becomes shorter and thicker. The seta of these segments then protrude out and get gripped into the soil. The contraction of anterior segments pull the posterior body of the worm forward. The contraction of longitudinal muscles passes backwards like a wave. Again a wave of contraction of circular muscles starts from the anterior end making it thinner and extended forwards. These alternating series of waves of extension and contraction bring about the locomotion of worm. Setae always protrude during longitudinal contraction and retract during circular contraction. During locomotion, the coelomic fluid serves as a kind of hydraulic skeleton. When compressed due to contraction of circular muscles, it provides stiffness to the body and aids in the relaxation of the longitudinal muscles. The earthworm moves at the rate of 25 cm per minute. The worms can move backward also. When the direction of wave is reversed, the worm crawls backwards.

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Shirish 9:13 PM   2 comments

Earthworm [Part 1]

The name earthworm is given to the annelid worms, because they live and burrow in the ground. Annelids are triploblastic, bilaterally symmetrical and coelomate animals. The presence of true segmentation (metamerically segmented) in their body is a diagnostic feature of these animals. The locomotary organs are setae or chaetae present in each segment. Phylum Annelida, also sometimes known as Annulata, contains elongated, vermiform and true segmented animals.

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Shirish 8:15 PM   2 comments

Human Evolution

Like any other species human also evolved over millions of years. The early stages of human evolution are studied by means of the comparative anatomy of fossils and the evidence of thee comparative biochemistry of present-day humans and other mammalian species. Humans belong to an order of class mammals called Primates. The present day order primates consists of two suborders: Prosimii, includes tree-shrews, lemurs, loris, tarsiers etc. and Anthropoidea, includes monkeys, apes and humans. Humans belong to the family Hominidae.

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Evidences of Evolution

The doctrine of organic evolution is supported by following evidences:

1. Structural evidence: The most extensive evidence in support of evolution comes from the study of structural similarities. Related groups of organisms possess homologous structure because of common ancestry. Among the vertebrates from the frog to man, the vertebral column, eyes, ears, brain and the digestive system are constructed on the same basic plan. Some homologous structures suggest a common ancestry. In plants, the structural similarities of roots, stems, leaves, flowers show the evolutionary tendencies of plants. Morphological similarities in the type of venation, shape of corolla, cohesion or adhesion of stamens among a group of plants suggest a common ancestry.

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Shirish 10:36 PM   2 comments

Origin and Evolution of Life

Origin of Life:

The ability to grow and produce new forms distinguishes living organisms fron non-living objects. The origin of life on Earth is a most complicated problem for thinkers, philosophers and naturalists from ancient time. Different views have been put forward concerning the origin of life by workers of different ages. some of the most important hypothesis and theories regarding the origin of life are as follows:

Origin of Earth and its Atmosphere:

The earth was probably originated 4600 million years ago. The sun and the planets were formed together from a spherical cloud of gases and cosmic dust by gradual condensation. The earth was so hot that everything in it probably existed in gaseous form. It was a molten fire-ball about 5000-6000 centigrade for millions of years. The gases condensed into a molten core and differnt elemnts got stratified according to their density. Heavy metals such as Nickel, Iron formed the solid core of earth whereas lighter ones came towards the surface of earth. Lighter elements like Hydrogen, helium, carbon, oxygen and nitrogen constituted the early atmosphere. The earth had a reducing atmosphere, i.e. the free oxygen was not found in volcanic gases, because the reduced substances immediately combined with oxygen to form oxides.

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Shirish 10:36 PM   1 comment

Structure of Cell [Part 3]

Plastids:

Plastids are cytoplasmic organelles about 5 micron in diameter and 3 micron in thickness, found freely in cytoplasm of the most of plant cell. they are not found in animal cell. the term plastid was first used by Schimper (1885). They are usually disc shaped and arise from small granular bofies, the protoplastids. Based on the types of pigments, three types of plastids are recognized: leucoplast, chloroplast and chromoplast. One form of plastid can change into another form, for example, in tomatoes the ovary contains leucoplasts which change into chloroplasts in young fruits and finally into chromoplasts as the fruit ripens.

1)Leucoplasts: [Gr. leukos: white; plastikos: formed] These are colourless plastids found in non-green parts of the plant such as under-ground stem, root and meristemic cells. They may be rod-like, spherical or oval in shape. Each leucoplast is bound by double layered membrane which encloses granular matrix. They contain few lamellae and on exposure to sun light change into chloroplast by developing thylakoid structure. Leucoplasts are mainly concerned with storage of various kinds of reserve food materials and are named variously such as amyloplasts (involved in storage of starch), elaioplasts or lipoplast (involved in storage of oil), aleuroplasts (involved in storage of proteins).

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Shirish 12:25 AM   No comment

Structure of Cell [Part 2]

Cytoplasmic Organelles:

Ribosome : The ribosomes were first reported in plant cells by Robinson and Brown (1953) and Palage (1995). They observed itin animal cell, usually attached to the outer surface of endoplasmic reticulum. The name ribosome was proposed by Haguenau (1958). It is a minute rounded ribonucleoprotein structure, consisting of RNA and proteins. the ribosome contains two unequal subunits and these subunits remain attahed together by means of binding force of magnesium atom. The larger subunit has dome like shape, while the smaller subunit occurs above the larger subunit as a cap like structure.

Occurence: The ribosomes occur in both prokaryotic and eukaryotic cells. In prokaryotic cell, it is found freely in cytoplasm. In eukaryotic cell, it is found freely in cytoplasm, matrix of chloroplasts, mitochondria or remains attached to the endoplasmic reticulum.

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Shirish 1:51 AM   No comment

Structure of Cell [Part 1]

Before discussing about the structure of cell, lets have a brief introduction of cell in terms of its structure. Cell is a microscopic protoplasm surrounded by the cell membrane. The protoplasm consists of the cytoplasm and the nucleus. In a plant cell, the cell membrane forms the outermost covering of the cytoplasm beneath the cell wall. The cytoplasm contains several living organelles and non-living inclusions. A cell under a microscope shows the following:

Cell Size:

An average cell varies from 0.01mm to 0.1mm in diameter. The cell of Acetabularia, an unicellular algae is about 10 cm long. The Ostrich egg is the largest cell which measures about 6 inches or 170*135mm and the smallest living cells are bacteria (0.1-10 micron). The smallest cell is Mycoplasma gallisepticum (0.1 to 0.2 micron). The nerve cells are the longest cells, that measure upto over a metre. A micron is one-thousandth (10^-3) of a mm or 10^-4 cm. One thousandth of a micron is millimicron, which is equal to 10^-6mm or 10^-7cm. Under the electron microscope, the unit of measurement is angstorm. An angstrom is one-ten-thousandth (10^-4) of a micron or ten-millionth (10^-7) of a mm.

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Cell Biology

So what is Cell? Cell is the basic structural and functional unit of living organism. It consists of microscopic mass of protoplasm surrounded by a cell membrane. it is the smallest unit, that can perform all the processes of life. In a unicellular organism, the single cell performs all metabolic functions such as growth, respiration, reproduction, digestion, excretion, etc. In multicellular organisms all the vital activities are the result of combined action of these cells. Hence, the cell is considered as basic unit of life. Robert Hooke(1635-1703) dicovered cell in 1665.

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