Twins and I.Q., Eugenics, Euthenics and Euphenics
Twins
Twins: Two birth occurring at the same time in human are called twins, they are of peculiar genetic interest. The hereditary basis of a number of human traits has been established by the study of twins. There are 3 kinds of twins.
(i) Identical or monozygotic twins: Identical twins are formed when one sperm fertilizes one egg to form a single zygote. As a result of separation of two daughter cells or blastomeres after the first cleavage, each of the cell develops into a separate individual. Such individuals are called identical twins. Since they develop from a single zygote, they are called monozygotic twins. They have the same genotype and phenotype and are of same sex. Differences if any, may be due to different environmental conditions.
(ii) Siamese twins or conjoint twins: Like monozygotic twins, siamese twins also originate from one zygote but the daughter cells formed as a result of first cleavage fail to separate completely and they remain joined at some point. They grow into two individuals joined together. Thus the two individuals called conjoint twins remain attached at one or more parts of the body. They were first studied in the country Siam, hence called Siamese twins. Siamese twins usually do not survive after birth although a few cases of their survival are well known. They are always of the same sex, same genotype and phenotype.
(iii) Fraternal twins: They are dizygotic twins formed from the two eggs fertilized by two sperms separately but at the same time. They may be both males, both females or one male and one female. They may have different genotypic constitution and different phenotype. Thus fraternal twins develop in same environment with different constitution but are the members of same age. They resemble each other just like any two brothers and sisters. Although they may be of same sex but due to different hereditary traits, they may carry congenital variations.
Among the twins fraternal twins are most common and Siamese twins are most rare.
Eugenics, Euthenics and Euphenics
Eugenics, Euthenics and Euphenics
(i) Eugenics: The term eugenics (Gr. Eugenes, well born) was coined by British scientist Sir Francis Galton in 1883. Galton is called ‘Father of eugenics’ as this branch has been started by him.
Eugenics is the branch of science which deals with improvement of human race genetically. This aspect of human betterment aims to improve the human germplasm by encouraging the inheritance of best characteristics so that defective characters may be eliminated. Eugenics attempts to attain its objective bilaterally by suggesting a number of ‘do’s and ‘don’ts’ to improve the human gene pool. The ‘don’ts’ are meant to check inheritance of the poor or undesirable germplasm, while the do’s aim at perpetuating desirable germplasm to be inherited. By this method aim of improvement of human race may be achieved by two ways :
(a) Positive eugenics : more...
Genetic Engineering
(i) Recombinant DNA technology
(a) Definition: Genetic engineering, a kind of biotechnology, is the latest branch in applied genetics dealing the alteration of the genetic make up of cells by deliberate and artificial means. Genetic engineering involves transfer or replacement of genes, so also known as recombination DNA technology or gene splicing.
(b) Tools of genetic engineering: Two enzymes used in genetic engineering are restriction endonuclease and ligases. R.E. is used to cut the plasmid as well as the foreign DNA molecules of specific points while ligase is used to seal gaps or to join bits of DNA.
The ability to clone and sequence essentially any gene or other DNA sequence of interest from any species depends on a special class of enzymes called restriction endonucleases. Restriction endonucleases are also called as molecular scissors or ‘chemical scalpels’. Restriction endonucleases cleave DNA molecules only at specific nucleotide sequence called restriction sites. The first restriction enzyme identified from a bacterial strain is designated I, the second II and so on, thus, restriction endonuclease EcoRI is produced by Escherichia coli strain RY 13. Restriction enzyme called EcoRI recognizes the sequence \[\begin{matrix}
G \\
C \\
\end{matrix}\begin{matrix}
\downarrow \\
T \\
\end{matrix}\begin{matrix}
A \\
T \\
\end{matrix}\begin{matrix}
A \\
A \\
\end{matrix}\begin{matrix}
T \\
A \\
\end{matrix}\begin{matrix}
T \\
\uparrow \\
\end{matrix}\begin{matrix}
C \\
G \\
\end{matrix}\] and cleaves the DNA between G and A on both strands. Restriction nucleases make staggered cuts; that is, they cleave the two strands of a double helix at different joints and blunt ended fragments; that is, they cut both strands at same place.
Characteristics of some restriction endonucleases
New Crops
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 \[\times \] diploid Rye) or octaploid, i.e., 2n=8x=56 (hexaploid Bread wheat \[\times \] 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 more...
Dogs and Cats
Dogs and cats are the closest pets of man. They are carnivores turned omnivores. They occurs wild in various parts of the world.
(i) Dogs: Dog was among the earliest animals domesticated by man. A large number of breeds have been produced by intensive inbreeding and artificial selection of a single ancestral dog species. These vary in form colour, size and fur. It has proved to be a faithful companion and guard of its master. The domestic dog, can is familiars, is found in almost all countries. It is useful in many ways.
(a) It can be trained to protect flocks (sheep or goat) and herds (cattle).
(b) It is helpful in tracking and running down the game such as hare and fox.
(c) It is a very useful animal for hunting.
(d) Some breeds, which have sharp sense of smell and sight, are employed to trace the criminal’s drug peddlers and prowlers.
(e) It can lead the blind persons.
(f) Eskimos use dogs to pull sledges (wheel less vehicles used over snow or ice).
(g) Dog raising is a profitable business. Pedigree dogs fetch high return.
(h) Dog is a symbol of loyalty.
(ii) Cats: Cat fails domestic us is a small, furry mammal. It has many breeds. It is domesticated to eradicated rats and mice. It is also a nice pet.
Cattles and Buffaloes
(i) Meaning of livestock: The word livestock refers to the domestic animals kept or dealt in for use or profit. It includes cattle, buffaloes, sheep, goats, pigs, horses, mules, donkeys and camels. The most important of these are cattle and buffaloes.
(ii) Cattle (Bos indicus) Buffaloes (Bos bubalus): The word cattle includes cow (adult female), bull (uncastrated adult male), bullock or OX (castrated adult male) and steer (young castrated male).
(iii) Importance of cattle and Buffaloes: Cattle and buffalo are most important forms of domesticated animals.
They are next to land in use for farmers. They are widely used for:
(a) Agricultural Operations: Cattle are used in agricultural operations such as ploughing, harrowing and levelling land; in harvesting and thrashing ripe crops; and in working wells, etc.
(b) Milk: Cows and buffaloes provide milk, an important human food with all the essential materials.
(c) Transport: Cattle are employed in cart driving to transport men and materials. However, they are being fast replaced by machines.
(d) Manure and fuel: The dung provided by them acts as a valuable manure for maintaining the fertility of the soil. It is also used for preparation of biogas or gobar gas. Dung cakes provide cheap fuel to the poor, but the fields get deprived of an important manure.
(e) Leather: Hides obtained from these animals are used for the preparation of leather goods.
(f) Glue and gelatin: Their bones, horns and hoofs yield glue and gelatin.
(g) Meat: Beef and buffalo meat are eaten by certain people
(h) Hair: Hair are used for making brushes.
(i) Hybridisation: Indian bulls are used for
(iv) Breeds of cattle: There are 26 breeds of cattle and 7 breeds of buffaloes in India. They differ in colour, general body build, form of horns, forehead and geographical distribution. The best cattle breeds occur in the drier regions of the country. The most important breeds of milk cows in the United States of America are Holstein-Friesian, Jersey, Quernsey, Ayrshire and Brown Swiss. Depending upon the utility, the cattle are classified into the following groups;
(a) Milch breeds that give good milk-producing cows,
(b) Draught breeds which give good working bullocks,
(c) General utility (dual-purpose) breeds the females of these breeds are good milk-producers and the bullocks are good draught animals.
Some Breeds of Indian Cattle
Sheep and Goats
There are many breeds of sheep (ovis aries) and goats (Capra hircus) in our country. Today sheep are raised in all parts of the world. Sheep provide us with wool, skin and mutton and goats provide us with milk, meat, skin and hair. The fine soft wool called pashmina is the underfur of Kashmir and Tibet goats. A sheep lives for about 13 years.
(i) Feeding of sheep and goats: Sheep feed on green tender grass or weeds or other herbage. Goats feed on a variety of trees by browsing on the buds and foraging on a variety of plants. Oil cakes and mineral mixture are also fed to keep sheep in good condition.
(ii) Breeding of sheep and Goats: To improve the quality of a sheep, cross-breeding experiments are usually done. For this purpose, a good quality wool yielding or mutton producing sheep is chosen and cross breed with exotic breeds like Dorset, Horn and Merino. About 19% of world goat population occurs in India. These differ in body build, colour, horn size, ear size, hair texture, etc. The wild goat, Capra hircus, of Baluchistan and shind is the ancestral stock of all the breeds of domestic goat.
Some breeds of Indian Sheep
Pigs
Pig, also called hog or swine, is an omnivorous, no ruminant, gregarious mammal of genus Sus. All breeds of pigs have descended from the European wild boar sus scrofa or a crossbreed of this and the Asiatic species, S. indicus. The care and management of pigs is called piggery.
Pigs are the most prolific breeders and quick growers among the domestic animals. A group of 10 sows (Female hog) and one boar may produce over 160 piglets in a year. Pigs are most useful domestic animals, especially of lower classes of society. They are most economical source of meat and animal fat. Pig meat, in general, is known as pork and the meat obtained from different parts of the body have been given different names, for example bacon obtained from the back and sides and ham from the back of the thigh. Sausages are prepared by fresh minced pork, free form bone and skin. The fat of pig squeezed from the body tissue is termed as lard. Lard is used as a fine cooking medium and in the manufacture of soaps lubricants, greases, candles and water proof materials. The wiry and stiff hairs obtained from the back and neck of the pigs and wild boars are known as bristles. The rough and coarse bristles are generally used for varnish work and painting brushes. The hide is used as leather and pig droppings are a good source of nitrogen, phosphorus and potassium for agricultural fields.
(i) Feeding of pigs: Indigenous pigs survive through scavenging on kitchen wastes and farm by products and human faeces. Pig keepers raise them on grass, straw roots and grains. As they can feed on human faeces, they serve as secondary host for tape worms.
(ii) Breeds and breeding of pigs: Pig breeding has now started on commercial scale. The improved exotic types, number of which is insignificant is maintained mostly at all the seven Regional Pig Breeding stations of the country. Some breeds of the pigs are given in table.
Important Breeds of Pigs
Breeds
Distribution
Native Pigs
1. Desi
Uttar Pradesh, Bihar, Punjab, Madhya Pradesh
2. Ghori
Manipur, Assam, Meghalaya, Arunachal Pradesh
Exotic pigs
1. Berkshire
U.K.
2. Large White Yorkshire
U.K.
3. Landrace
Switzerland, Denmark
(iii) All India Co-ordinated research project: The ICAR initiated an All India Co-ordinated research projects on pigs during the fourth five year plan. The project more...
Horses, Donkeys and Mule
(i) Distinguishing Features: The horses (Equus cabalus) are solid- hoofed, non-ruminant quadrupeds with long, pendant mane and tail bearing long hair all over. They are intelligent animals. They learn fast are faithful pets and can adapt to all sorts of climatic conditions.
(ii) Feeding: Horses are fed on oats, barley, gram and hay. Common salt is also added to their diet. Green grass may also be given if available.
(iii) Breeding: If compared to other animals, horses have a low reproductive rate. Controlled natural mating in horses has been in practice in India for a long time. A high professional skill is required for rearing, training and medical care of race horses.
Important breeds of Indian Horses
Name
Regions
1. Kathiawari
Rajasthan and Gujrat
2. Marwari
Rajasthan
3. Bhutia
Punjab and Bhutan
4. Manipuri
North-eastern mountains
5. Spiti
Himachal Pradesh
6. Zanskari
Ladakh
Donkeys
(i) Distinguishing Features: Donkeys are smaller than horses but have larger head, longer pinnae and narrower hoofs. Their mane is erect and tail has a tuft of hair at the tip.
(ii) Feeding: The donkeys mainly feed on straw and fodder. They are often let free to graze on the roadside.
(iii) Breeding: There are two breeds of donkeys in our country: small, dark grey and large, light grey to almost white. The grey donkey occurs in most parts of the country. The white donkey, also called wild ass, occurs in Rann of Kutch. Donkeys have descended from the wild ass Equus asinus of Abyssinia.
Mule
Mule is the hybrid between male ass (jack) and female horse (mare). It has the stamina of ass and size of horse, but is sterile. Similarly, the cross between male horse (stallion) and female ass is called hinny.
Mules are known for their toughness. Since they are sexually sterile, they have to be produce every time a new.
(i) Feeding: They are fed mainly on green fodder, crushed grams and barley. They are also given salt.
(ii) Breeding: Indian army has imported male donkeys from Europe for breeding mules. Army uses tow type of mules: (a) General service type and (b) Mountain artillery type. The latter are firm footed and can carry heavy loads on steep terrain.
(iii) Common Disease of Equines: The horses, donkeys and mules suffer from more...
Camel
The camel is a large, horn less, ruminant mammal of genus Camel us. It is popularly called “the ship of the desert” because of its great travelling power in a desert. It is a valuable beast of burden in hot desert and semi desert regions as it can live on minimum food and water when travelling with load.
(i) Types of camels: There are two types of camels:
(a) Arabian camels (Camels dromedaries): With a single hump, short hair and found in North Africa to India. It does not occur in wild form.
(b) Turkish or Bactrian camel (Camel us Bactrian us): With two humps, long hair and found in Gobi desert of central Asia. It occurs in wild form also.
(ii) Feeding: Camels are fed on dry fodder (barley, straw) supplemented with chopped green fodder made of pulses, mustard and green peas. They browse on trees, shrubs and bushes. The size of the hump is a good indicator of its health.
(iii) Breeding: There are four kinds of camels in India. These are Jaisalmeri, Sindhi and Bikaner found in Rajasthan and Kutch found in Gujarat. They have a well-defined breeding season. Camels breed in winter (November to March).
(iv) Diseases: Camels suffer diseases such as anthrax, pneumonia, camel-pox and surra.
Elephant
Elephants are chiefly found in forests with tall trees where bamboos grow in profusion. They have very poor sight but sense of hearing and smell is highly developed.
(i) Feeding: Daily food intake is considerable, but only partially digested and utilization is low. Natural food includes bamboo shoots, leaves and various fruits. Working elephant are fed straw, hay and crushed grain as a supplement.
(ii) Breeding: Puberty occurs at between 8 and 12 years. The gestation period is 21 - 22 months. The calving interval is 4 years. Elephants may live for up to 90-100 years. Elephants are of two types: African elephants and Indian elephants.
Differences between Indian Elephant and African Elephant
Indian elephant (Elephas maximus)
African elephant (Laxodonta africans)
1. Physical Features
Small ears, High domed forehead with 2 prominance on top of skull. One process on trunk tip Convex backed. Tusks in males only, not always
Large ears convex sloping forehead.
2. Mature at
25 years
25 years
3. Weight at maturity
Male 3000 kg
Male 6000 kg
4. Geographical distribution
Ceylon, India, Burma, Thailand, Vietnam, Laos, Malaysia, Indonesia
Sericulture
Sericulture is the breeding and management of silk worms for the production of silk. It has been practiced in India since second era or century B.C. The silk which is produced by silk worm is of a valuable natural protein fibre. Silk worms are the larvae of silk moths. The rearing of silk worm for the production of silk is known as sericulture.
(i) History of silk: Historical account of use of silk and rearing of silk worm eggs, larvae and cocoons are available from china. It was Lotzu the empress kwang-Ti who for the first time discovered the silk thread and its source the silk worm cocoon. The technique of sericulture was kept as a secret by the chines people. In about 550 B.C. The sericulture technique was diffused to European countries. The available mythological literature deals with facts rearing the use of silk in ancient India. By about 1000 A.D. the sericulture was in practice in China, Europe and India, China was the leading country in this field.
At present the sericulture is practiced in China, Japan, Korea, India, Brazil, Russia, France and Italy. Some of the south East Asian countries. China is topmost country producing some 48% cocoons and 40.9% of row silk. Next biggest silk producing country is Japan, India is placed in third position as for as the production of silk in term in quantity is concerned.
(ii) Silk in India: As far as silk as a fabric is concerned it is a matchless fabric second to none. Therefore, silk garments have been a favorite choice since ancient times. Use of silk clothes finds its mention from pre-historic period. There are description of use of silk clothes from Vedic period. In Ramayana and Mahabharata period the silk clothes adored the bodies of royal princess, prince, kings and queens. It attire of the rich people. The silk clothes were used to the superiority of social and economic status. It was given in gifts by rich people and royal families.
In the medieval period the silk was a recognised commodity of commerce. The silk clothes and raw silk were imported from China and Japan. Later on it was also imported from Europe. By the Moghul period India had a rich heritage of silk clothes. The silk was imported as raw silk. It was spun into silk thread and silk clothes were woven in handlooms silk clothes became almost a craze among royal families and rich persons. A number of such looms were in operation in Banaras, and different parts of Uttar Pradesh, Kashmir became centres for the production of cocoons and rearing of silk worm. Sporadic silk textile centres were also present in South India. It was in 1905-1906 that a scientific investigation in the field of sericulture was undertaken in India by the Indian Institute of Agricultural Research at Pusa, New Delhi. It was Leroy who conducted research on the silk worm and potentialities of silk production in India. more...
Eugenics, Euthenics and Euphenics
Eugenics, Euthenics and Euphenics
(i) Eugenics: The term eugenics (Gr. Eugenes, well born) was coined by British scientist Sir Francis Galton in 1883. Galton is called ‘Father of eugenics’ as this branch has been started by him.
Eugenics is the branch of science which deals with improvement of human race genetically. This aspect of human betterment aims to improve the human germplasm by encouraging the inheritance of best characteristics so that defective characters may be eliminated. Eugenics attempts to attain its objective bilaterally by suggesting a number of ‘do’s and ‘don’ts’ to improve the human gene pool. The ‘don’ts’ are meant to check inheritance of the poor or undesirable germplasm, while the do’s aim at perpetuating desirable germplasm to be inherited. By this method aim of improvement of human race may be achieved by two ways :
(a) Positive eugenics : more... 
