Current Affairs 12th Class

The technique of in-vitro fertilization and in-vitro development followed by the embryo-transfer in the uterus of the normal female to start the development and finally leading to normal birth, is called test tube baby. History : First attempt to produce a test tube baby was made by a Italian scientist, Dr. Petrucci (1959 A.D.). Although, this human embryo survived for only 29 days, but his experiment opened a new filed of biological science. The first test tube baby was born to Lesley and Gilbert Brown on July 25, 1978, in Oldham, England. Mrs. Brown had obstructed Fallopian tubes. Dr.Patiricke Steptoe and Dr. Robert Edward both from England experimented on Mrs. Brown successfully. the world's first test tube baby (a baby girl) was named as Louise Joy Brown. Later, test tube babies were also born in Australia, United States and some other countries. India's first test tube baby was born on 3rd October, 1978 in Kolkata. Her name was Kanupriya Aggarwal and was created by Dr. Subash Mukherjee. Procedure : It involves the following steps : (1) Removal of unfertilized ovum from reproductive tract of a female. (2) Ovum is kept under aseptic conditions. (3) Fusion of sperm and ovum in a culture medium, outside the female body, to form the zygote. (4) Zygote is stimulated to develop in vitro upto 32-celled stage. (5) Developing embryo is implanted on the endometrium of the uterus at 32-celled stage. So the pregnancy in the woman starts and further development of the child continues in the womb till it is born. Such a baby called a test tube baby. Significance (1) It is boon to infertile mothers. (2) It can be used for men with Oligospermia (low sperm count). (3) Old superior cows can donate oocytes. Embryos can be frozen and preserved in an embryo tank for 10 years for future use. In very rare cases, a surrogate mother may have to be used to bring up in vitro fertilized ovum to maturity. Though biological realization of a test baby is a remarkable achievement, it has raised several ethical and legal problems like the right over the child.

Population Trends in the World The distribution of human population is not uniform throughout the world. Only about one third of the total land area is inhabited. Of the inhabited areas, some are thickly populated, others sparsely. This depends upon the availability of the requirements of life. About 56% of the total world population resides in Asia alone. Bangladesh is the most thickly populated country, and Australia, the most thinly populated. Annual Birth, Death and Growth Rates for Human Population in 1973
S. No Region Population (Millions) Average Annual Birth Rate per 1,000 Individuals Average Annual Death Rate per 1,000 Individuals Annual Growth Rate Percent  
(1) World 3860 33 13 2.0
(2) Developed Countries 1120 more...
Population : India’s population according to the provisional totals of Census of India 2001 at the 00.00 hours of Ist March 2001 is 1,027,015,247, out of which the population of Madhya Pradesh is 60,385,118, state thus contributing 5.87% share to India’s total population. Madhya Pradesh is the 7th largest state population-wise whereas it is 2nd in terms of its geographical spread and contributes 9.38% to the country’s total area of 3,287,263 sq.km.   Population 1901 to 2001 in Madhya Pradesh
Year Population Year Population
1901 12,679,214 1961 23,217,910
1911 14,249,382 1971 30,016,625
1921 13,906,774 1981 38,168,507
1931 more...
(1) Population density : Population density is the number of individuals present per unit area or volume at a given time. For instance, number of animal per square kilometer, number of trees per area in a forest, or number of plank tonic organism per cubic meter of water. If the total number of individuals is represents by letter N and the number of units of space by Letter S, the population density D can be obtained as \[D=N/S.\] Space is indicated in two dimensions \[({{m}^{2}})\] for land organisms, and in three dimensions \[({{m}^{3}})\] for aquatic organisms and for the organisms suspended in space. (2) Birth rate or Natality : The birth rate of a population refers to the average number of young ones produced  by birth, hatching or germination per unit time (usually per year). In the case of humans, it is commonly expressed as the number of births per 1000 individuals in the population per year. The maximum birth rate of a species can achieve under ideal environmental conditions is called potential natality. However, the actual birth rate under the existing conditions is much less. It is termed realised natality. (3) Death rate or mortality : The death rate of a population is the average number of individuals that die per unit time (usually per year). In humans it is commonly expressed as the number of death per 1000 persons in a population per year. Lowest death rate for a given species in most favourable conditions is called potential mortality, while the actual death rate being observed in existing conditions is called realized mortality. (4) Survivorship curve : The death rate of population can be easily represented by survivorship curve. In this curve time is plotted against number of survivors. There are three kind of survivorship curves. (i) Diagonal curve : If death rate of different age group organism are equal then the curve is represented or plotted as a straight line. Example : Hydra, mice and many adult birds. (ii) Convex curve : When organism completed their potential life spawn and died in old age then the curve is convex, the curves goes horizontal till potential life spawn and then decline rapidly. Example : Men, rabbit and many mammals. (iii) Concave curve : This kind of curve most found in such organism who die before their potential life spawn. Example : Fish, Oysters and Invertibrates.     (5) Vital index : The percentage ratio of natality over mortality is known as vital index i.e. natality / mortality \[\times 100.\] It determines the growth of a population. (6) Immigration : It is permanent entry of additional person into the existing population of a country or region from out side. Example; Many Nepalese and Chinese come to settle in India. (7) Emigration : It is the permanent departure of some persons from the existing population of a region to a different state or a foreign country. Example; Many Indians go to Western more...

Meaning : The regulation of conception by preventive methods or devices to limit the number of offspring  is called birth control. Methods : A variety of methods are known for birth control. The birth control methods which deliberately prevent fertilization are referred to as contraception. These methods are of 2 main types : temporary and permanent. (1) Temporary  Methods : These  are  further  of  many types : (i) Safe Period (Rhythm Methods) : A week before and a week after menses is considered the safe period for sexual intercourse. The idea is based on the following facts- (a) Ovulation occurs on about the 14th day (may be 13 th to 16th day) of menstruation. (b) Ovum survives for about 1-2 days. (c) Sperms remain alive for about 3 days. This method may reduce the chances of pregnancy by about 80 percent. However, a great care is needed in its use. Rhythm method is also called natural family planning. i.e., a few days before and a few days after ovulation. Changes in cervical mucus and body temperature during the menstrual cycle mark the ovulation time. Thus, the natural family planning requires adequate knowledge of these physiological signs. Some couples use the natural family planning method of increase the chances of conception so that unplanned pregnancies are avoided. (ii) Coitus Interruptus : This is the oldest method of birth control. It was in use over 2,000 years ago. It involves withdrawal of the penis from the vagina by the male before ejaculation so that semen is not deposited in the vagina and there is no fertilization. (iii) Spermicides : Foam, tablets, jellies, pastes and creams, if introduced into the vagina before sexual intercourse, adhere to the mucous membrane and immobilise and kill the sperms. These contain seprmicides such as lactic acid, citric acid, boric acid, potassium permanganate and Zinc sulphate. (iv) Mechanical Means : These are of 3 types : (a) Condom (Nirodh) is a thin sheath, usually made of rubber, to cover the erect penis. It is the most widely used contraceptive by males in India as it is cheap and easily available. It is given free also by government. It checks pregnancy by preventing deposition of semen in the vagina. Condom is also a safeguard against infection of AIDS and sexual diseases. (b) Diaphragm and cervical cap are dome-shaped rubber plastic covers that are fitted on the cervix in the female's vagina, and check the entry of sperms into the uterus. These must be kept fitted for at least six hours after sexual intercourse. They are smeared with a spermicidal jelly or cream each time they are used. The diapharm and cervical cap are the counterparts of condoms in the female (c) Intrauterine devices (IUDs) are plastic or metal object placed in the uterus by a doctor. These include loop, copper-T, spiral, ring, bow, shield, etc. They prevent the fertilization of the egg or implantation of the embryo. Their presence perhaps acts as a minor irritant and this makes the more...

Population growth refers to the increase in its size. It is determined by the number of individuals added to the population and the number of individuals lost from the population. Addition occurs by births and immigration. Loss results from deaths and emigration. If more individuals are added than are lost i.e., the vital index is more than 100, the population will increase or show positive growth. If more individuals are lost than are added i.e., the vital index is less than 100, the population will decrease or show negative growth.  If addition and loss are balanced, i.e., the vital index is 100, the population will become stationary or show zero growth. Malthus Theory of Human Population Growth : Thomas Malthus, a British political economist, put forward a theory of human population growth in 1778. Malthus in his "Essay on the principle of population" pointed out that population tends to increase in geometric progression while food supply increase only in arithmetic progression. Faster growth of population than of its requirements causes an imbalance between the two. When this imbalance reaches a certain limit, environmental factors like famine, epidemic of a disease, earth quake, flood, war etc reduce the population to a size, the available resources can support. The factors that control the population size were called positive checks by Malthus. Natural Control of Population Growth : Growth of a population is controlled by an interaction between three factors: biotic potential, environmental resistance and carrying capacity of environment. (1) Biotic or reproductive potential : Biotic potential is the natural capacity of a population to increase at its maximum rate under ideal environmental conditions and stable age and sex ratios. The biotic potential for all animals is very high. If unchecked, the numbers of any species will quickly over run the world. Biotic potential in the human female is estimated to be about 12 per female during its reproductive period between the puberty and the menopause period. (2) Environmental Resistance : In nature full biotic potential of an organism or population is never realized, since conditions are rarely ideal. Various harmful environmental (abiotic) factors like non-availability of food and shelter, natural calamities like drought, cloud bursts, floods, fires, temperature fluctuations, accidents, etc. and certain biotic factors like pathogens, parasites, predators etc. check the biotic potential from being realized. The sum of all these inhibitory factors is called environmental resistance. (3) Carrying capacity : It is defined as “Feeding capacity of an environment of  an ecosystem for a population of a species under provided set of conditions”. When a population reaches the carrying capacity of its environment, the population has zero growth rate. So the population generally stabilizes around the carrying capacity. The carrying capacity of the earth for human population is considered to be about 8 to15 billions. Carrying capacity of the environment for a population depends upon three major components : (i) Productive systems which produce food and fibre e.g. croplands, orchards, etc. (ii) Protective systems which buffer air and water cycles more...

Aim : It is a technique to determine : (1) Sex of the developing baby. (2) Genetically controlled congenital diseases. (3) Metabolic disorders in foetus. So amniocentesis is a pre-natal diagnostic technique. Procedure : It involves following steps : (1) Location of the foetus is determined by a technique called sonography (using high frequency ultrasound waves) to prevent accidental damage to the foetus. (2) A fine hollow needle is passed through the abdominal and uterine wall of a pregnant female (about 14th to 15th week after conception) into the amniotic cavity.     (3) A small amount of amniotic fluid is withdrawn. It contains foetal skin cells and a number of proteins, especially enzymes. The cells can be cultured in vitro for further examination.   Significance (1) Sex determination : The somatic cells of foetal skin drawn with the amniotic fluid are stained to determine the presence of sex chromatin (barr body). Presence of barr body indicates that the developing foetus in female as female is with 2 X-chromosomes out of which one X-chromosome is active, while other X-chromosome is heterochromatised into a darkly stained barr body. (2) Congential disease : By Karyotypic studies of somatic cells, abnormalities due to changes in chromosome number like Down's syndrome, Turner's syndrome, Klinefelter's syndrome etc. can be determined. (3) Metabolic disorder : By the enzyme analysis of amniotic fluid, different types of inborn metabolic disorders like phenylketonuria, alcaptonuria etc. can be detected. These inborn errors are caused by the absence or inactivity of specific enzymes due to gene mutations. So with the help of amniocentesis, if it is confirmed that the child is likely to suffer from some incurable, congenital defect, the mother can go for abortion. (4) Drawback : However, these days, the amniocentesis is being misused also. Mothers even get their normal foetus aborted if it is a female. This is just equivalent to killing of a normal child. So Govt. of India enforced the Pre-natal Diagnostic Techniques (Regulation and Prevention of Misuse) Act, 1994, since January 1, 1994 under which all genetic counselling centres and laboratories are required to apply for registration. The violation of this Act can bring a fine of Rs. 50,000 and imprisonment for two years. The doctor's registration is also cancelled till the complaint is disposed of. (5) Chorionic Villus Sampling (CVS) : Amniocentesis is possible without a chance of injuring the foetus with the needle only after the sixteenth week of pregnancy. At this time, abortion is not safe. A new technique, named Chorionic Villus Sampling (CVS), can be done during the eighth to tenth week of pregnancy when abortion is safe for the woman. For CVS, cells are sucked into a catheter passed through the cervix. CVS technique provides a mass of rapidly dividing foetal cells, thus facilitating the examination of chromosomal disorders.  

Out of about 3,50,000 known plants at this time, a few i.e., about 100. Scientists are in search of less known and underutilized crop plants, which can be used for food and other purposes and thus exploitation of traditional plants can be reduced. Such under-utilized and under-exploited plants are known as new crops. Some of these new and underutilized crops are as follows : (1) Triticale : Triticale is the first man made cereal or crop,  which has been produced by intergeneric hybridization between common wheat (Triticum aestivum) and European rye (Secale cereale) with a view to combine characters of these two parent plants. Triticale is hexaploid, i.e, \[2n=6x=42\] (tetraploid Durum wheat × diploid Rye) or octaploid, i.e., \[2n=8x=56\] (hexaploid Bread wheat × diploid Rye). Triticale is the first new man-made plant to join the rank of cereals which have long evolutionary plants are being used for fulfilling man's daily requirements history. Triticale or triticosecale is not suitable for purpose of bread making due to low gluten content, but it is a good forge crop. Triticale is grown all over world, mainly in USSR. (2) Winged bean (Psophocarpus tetragonolobus family Leguminosae) : This is a herbaceous plant, which has capacity of nitrogen fixation. The tuberous roots, leaves, shoots, long pods with prominent wings and seeds are highly nutritious due to rich source of proteins and edible for humans as well as livestock. When green, the pods, leaves and shoots are used as vegetables, unripe seeds may be used as soups and ripe seeds can be roasted. The ripe seeds contain about 34% proteins and 18% oils (similar to soybean). Further this plant can be used as a green-manure plant, fodder plant and also as a cover crop. (3) Jojoba or Hohoba (Simmondsia chinensis) : This is a shrub, which is native of Mexican deserts. It is important drought desert plant, because it can survive under poor soil and low moisture conditions and hence is being grown in deserts. The seeds of this plant contain about 50% liquid wax, which is similar to sperm whale oil (spermaceti). This liquid wax was originally used in cosmetics, but now is also being used in high performance lubricants. (4) Guayule (= Wayule, Parthenium argentatum family Asteraceae) : It is commonly known as carrot grass or congress grass. This is native of America and nowadays it is most troublesome terrestrial weed in India and is present in almost all states of India. The roots of this plant secret transcinnamic acid, which inhibits the growth of other plants (allelopathy). This is a shrub and can grow on poor desert soils. This plant is nowadays used in obtaining rubber, which is called guayule rubber, which is similar to para rubber or hevea rubber. The body of this plant contains caotchouc granules, which are ingredient of rubber. The plant contains 12- 20% rubber on dry wt. basis. This plant can be a natural source of rubber in future. (5) Leucaena or Subabul/Loo-See-na/Loo-kee-na (Leucaena leucocephala family Leguminosae) : This more...

The environment is the aggregate of all those things and set of conditions which directly or indirectly influence not only the life of organisms but also the communities at a particular place. Any external force or influence, which surrounds and affects the life of a plant in any way, becomes a factor of its environment. These factors are called environmental factors and may be living (biotic) as well as non-living (abiotic). The abiotic factors affect the structure, life history, physiology and behaviour of organisms. The biotic factors mostly influence growth and reproduction. The environmental conditions which influence the life and development of plants, each part of the environment is called ecological factors. Ecological factors are grouped into four main classes (ecological factors) which are as follows : Climatic factors : The study of climatic factor is known as climatology. The chief climatic factors are : (1) Water : Rainfall is the chief source of soil moisture. Water exchange between earth surface and atmosphere is called hydrological cycle. Humidity of the air is expressed in terms of relative humidity. It is measured by hygrometer (Psychrometer). Epiphytes and cryoptogamic plants grow in those regions where relative humidity is high. (2) Light : Light (solar radiations) is a very important ecological factor as it is the source of energy to the whole biosphere. It enters the biosphere through the process of photosynthesis performed by green plants and other autotrophs. Here organic food is manufactured from inorganic raw materials. Solar energy is changed into chemical energy of food. The radiant energy of sunlight carries out all important functions, without this life except few bacteria would disappear. On this basis of relative light requirements and the effect of light on the overall vegetative development, plants are classified ecologically into following categories : (i) Heliophytes are popularly called sun plants because they grow in open in full sunlight. They possess a number of characteristics like. (ii) Sciophytes are shade plants which grow in areas having moderate to low intensity light, as below the shade of other plants. Optimum growth occurs with light of 10-30% of full sunlight. The plants grow in total darkness are called etiolated (Long, thin, weak and yellow in colours). (3) Temperature : Temperature influences every reaction and activity of organisms. Temperature shows daily as well as annual variations. The phenomenon of change of temperature between day and night and in different seasons of the year is called thermoperiodicity. It is of two types, diurnal (or daily) and seasonal (or annual). Thermoperiodicity determines periodical phenomena like seed germination, stem growth, flower formation, fruiting, dispersal, maturation of gonads, breeding, egg laying, etc. Low night temperature is suitable for seed germination in many plants, e.g., Rumex, Asclepias. Cooler nights also help in increasing size of tuber in Potato and fruit setting in Tomato. Organisms adapted to live at relatively constant temperature during the whole year are known as stenothermal, e.g., many palms, corals, snakes and some fishes. The organisms which can tolerate large changes of more...

The energy obtained from biological sources is called bioenergy. Bioenergy is the use of biomass (organic matter) to produce electricity, transportation fuels or chemicals. Bioenergy sources include agriculture and forestry residues and the organic components of municipal and industrial wastes. Fossil fuels (coal, petroleum and natural gas) is not included under bioenergy. Only 0.2% of solar radiations reaching the earth is converted into biomass. This amount is about-10 times the energy produced from nonbiomass sources. Being a tropical country, India receives more solar radiations and therefore has high potential for biomass synthesis to meet the requirement of energy. Bioenergy is obtained from following types of biological sources: Animal energy : Animal energy is basically of two forms : (1) Human muscle power (HMP) : It is the form of animal energy, which is used throughout the world in the form of physical work by human race like farmers in the field, women in house work and non agricultural labourers like artisans in wood work, gardeners, etc. A major part of the energy utilized today belongs to this type and it constitutes about 1/5th of the total generated electricity in India. Thus, it constitutes the significant part of energy used. (2) Draught animal power (DAP) : Animals are domesticated not only for providing us with food, hides and bones but they are also used in agriculture and transport. These animals play an important role in villages. India has about 84 million of work animals; 70 million bullocks; 8 million buffaloes and one million each to horses and camels. In addition mules, donkeys, elephants and yaks are also used. 50 percent of the Indian farmers have holdings less than two acres each, as a result they cannot use tractors. More than 15 million animal-drawn carts are use in India. Carts have the advantage that they can be used on all types of roads in all terrains. The energy potential of DAP is enormous. Suppose if each animal generates 0.5 horse power then the installed capacity of animals comes about 42 million horse power or 30,500 MW. This value is almost equal to total electric power generation in India. Because of poor quality of animals and outmoded designs of carts and agricultural machinery, full potential of DAP has not been realised in India. Methods recommended to achieve this are : (i) Improved breeds of draught animals. (ii) Use of better carts.  (iii) Proper management of grazing lands and pastures. (iv) Supply of nutritious fodder.  Biofuels and Biomass : They are fuels of biological origin. Biofuels are major source of energy. They are renewable and if used properly and efficiently they can solve the energy problems of developing countries. Biomass is the term applied to all materials whose origin can be traced to photosynthesis. Biomass can be used to generate producer gas, to run water pumps for irrigation, to obtain alcohol, to replace petrol, to generate biogas for cooking and lighting and to generate electricity.   Ways of utilising biomass as fuel more...



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