Motion in Vertical & Horizontal Circle - Physics

Circular Motion:  When a body moves in circle, its motion is called circular motion or angular motion. Circular motion may be divided into two type.Motion in a horizontal circle.Motion in a vertical circle.Motion in Vertical Circle:   In case of vertical circle, acceleration due to gravity plays a role at every point and changes the speed at every point of the motion.Motion in horizontal Circle:  In this case, acceleration due to gravity does not impart any role in change of speed. However, acceleration acts continuously even...

Read More

Genomic Library | Biotechnology

It consists of copy of genetic information of a species in a preferred environment. This library provides easy access to a preferred gene for its further copying or manipulation. In order to establish a genomic library of a particular species. Its DNA is fragmented by means of restriction enzymes and then the fragments are inserted into the plasmids and Bacteriophages which are introduced into bacteria. Such bacteria are cultured at controlled conditions so that they can be used later ...

Read More

Tissue Culture | Biotechnology

Tissue culture is a test tube  method used to create and clone novel plant varieties. A method in which whole plants grow by cultruing small pieces of tissues cute from the parent or even single parenchyma cells on an artificial medium containing nutrients plant cells are totipofient (a small cell with full genetic potential of organism). In 1950 carrot was produced from a single carrot phloem cells the cultured cells divided to form undifferentiated callus. This test tube plant can than be transferred to soil where they continue their...

Read More

Gene Sequencing | DNA molecules

Gene sequencing is a method of determining nucleotide sequence of a gene (DNA molecules). This gene sequence can provide great deal of information. It is fastest way to determine amino acid sequence of its polypeptide. It provides location of restriction site with in a gene which can be manipulated further later on. Man's phases of gene friquencing are firstly to cut genes into specific small pieces, then each fragment is individually sequenced. Most sequences, that are determined are being collected in computer data bank that are valuable...

Read More

Incomplete Dominance - Biotechnology

F1 offspring of Mendel's classic pea crosses always looked like one of the two parental varieties because of the complete dominance of one allek - over another. Many characteristics in a variety of organisms show this mode of inheritance. But many others do not. They may show another phenomenon of inheritance called incomplete dominance or intermediate inheritance. It is a phenomenon of inheritance in which dominant - alleles of contrasting characters are not completely dominant over other resulting that heterozygous individuals have phenotypes...

Read More

Test Cross | How it Performs - Botany

All plants produced in F2 generation may either have TT 01 IT genotypes. Mendel devised simple way to distinguish the genotype. It is known as lest cross. The oigantsins of dominant phenolype (tall) hut unknown genotype is crossed to homozygous recessive individual eg. a tall plant is crossed with a dwarf plant. It tall plant is homozygous (IT) and F1 plants would he tall (Tt) and one half dwarf (Tt) exhibiting a ration 1:1. This ratio is called test cross rat...

Read More

Ionic Bonding - Chemical Bonding

An ionic bond is formed when a metal atom transfers one or more electrons to other atom. Na ---> Na (positive) + e (Negative)F  + e -----> F (Negative)The Oppsitely charged ions get attraction through electrostatic force of attraction to form an ionic Bond.    If the electronegativity  difference between the atoms is equal to or greater than 1.7 the bond forms between the atoms have more than 50 % ionic character.In the solid each cation surrounds itself with anions and each anion with cations. In this ...

Read More

Hydrogen Bonding - Second Year Chemistry Topic

Hydrogen bonding is said to be formed when slightly acidic hydrogen attached to a strongly electronegativity atom such as F, O and N is held with weak electrostatic forces by the non-bonded pair of electrons of another atom. That is, it is a dipole-dipole interaction.Of all the electronegative donor atoms, only F, O and N enter into stable H-bond formation.Greater the electronegativity difference between the bonded atoms, stronger is the Hydrogen bonding.For example: The electronegativity difference between F and H is greater than that of between...

Read More

Law of Conservation of Angular Momentum - Artificial Satellite & Critical Velocity

The law of conservation of angular momentum states that the angular momentum about any axis of a given rotating body or a system of bodies is constant, if no external torque acts about that axis.       L(total) = L1 + L2 + L3 + ........ = Constant        The axis of rotation of an object will not change its orientation unless an external torque causes it to do so.Rotational Kinetic Energy:         If a body is spinning about an axis with constant angular velocity,...

Read More

Geo-stationary & Communication Satellite

Geo-stationary Orbits:     Geo-stationary satellite is the one whose orbital motion is synchronized with the rotation of the Earth. In this way the synchronous satellite remains always over the same point on the equator as the Earth spins on its axis. Such a satellite is very useful for worldwide communication, weather observations, navigation and other military uses 4.23 X 104 km is the orbital radius measured from the center of the Earth, for Geo-stationary satellite. A satellite above a particular point on the surface...

Read More

Genetic Coding brief Explanation

The sequence of nucleotide in DNA and RNA directs, the oriler of amino acid in a protein. There is code of each 20 amino acid found in Protein. Each code word is called carbon and is made up of 2 bases such as AG; there would be only 16 codons not enough to code for 20 amino acids. If each codon were made up of 3 bases, such as AGC, there would be 64 colons, more than enough to code for 20 different amino acids. There genetics code is triplet code and each codon has 3 nucleotide bases.Genetic code is degenerate i.e. most amino acids have...

Read More

Battle of Hunain

Before the Holy Prophet (P.B.U.H) could leave Makkah for Madinah, he received reports that the Hawazin and Saqeef, the two very strong and warring tribes of Taif, had collected a large army for attacking the Muslims. The Holy Prophet (P.B.U.H), therefore, postponed his departure for Madinah and made preparations for meeting this new challenge. He proceeded against them with an army of 12,000 Muslims, ten thousand of which had come from Madinah and two thousand were the new converts to Islam.    Probably the enemy had received...

Read More

Forest Ecosystem

Forest occupies roughly 35-40% of the land surfaces of the earth. In Pakistan the forest occupy about 6% of the total land area. The forest of the world have been classified into three kinds as coniferous, temperate and tropical forest. Coniferous forests are confined to Northwern Hemisphere where summer is short and winter is long and very cold. The temperature forest found in USA. Western Europe and East Asia, have mild temperature and moderate rain fall. The tropical rain forest grows in equatorial region where humidity is high, rainfall...

Read More

Some Outstanding Qualities of the Prophet Mohammad (P.B.U.H)

The Holy Prophet was totally different from the people among whom he was born and with whom he lived as a child and adult. He never a lie and was known as Sadiq and Amin --- The Truthful and Trustyworthy. He talked politely and never used abusive language. In his dealings with people, he always followed the principal of justice. He remained engaged in trade for many years, which he conducted with honesty and intregity. Those who dealt with him in business had the fullest confidence in his intregity. Even his enemies deposited their valuables...

Read More

Nitrogen Cycle - How works nitrogen ?

Nitrogen is indespensible in nature, it is essential for chlorophyll and amino acids which form proteins. It constitutes main bulk of atmosphere, where it is present in about 78% in ratio. The atmospheric nitrogen is insert and does not readily participate in any reaction. However it is cycled from environment to organisms and back to environment by several paths. Nitrogen is fixed from atmosphere through different sources and is absorbed by the plants in the form of nitrat...

Read More

Appoaches To Ecology

There are several factors, which interact in a particular locality due to this this there are several approaches to undertake ecological investigations. Each approach has its own merits and demerits. Thus ecologists use one of the suitable approach to understand ecological phenomenon. These approaches are population approach or autecology, community approach or synecology, ecosystem approach, habitat approach, evolutionary and historical approach. ...

Read More

What is Test Cross - Test Cross Notes

Cross fertilization of a phenotypically dominant individual with a hemozygous recessive individual is called a test cross. It helps in determining the homozygosity or heterozygosity of the dominant parent. When dominant homozygous parent is crossed with recessive, all the offspring will be dominant phenotypically. But when cross is between heterozygous dominant with recessive then half will be dominat and half recessive offspring are produced.       The result are shown...

Read More

Short Note on Meiosis

Meiosis or reduction is a rather complicated type of cell division occurring in the reproduction of germ cells at the time of gamete formation. The process of meiosis occurs both in plants and animals.     In animals it occurs during gametes formation whereas in plants, it occurs during spores formation. It has already been stated that every species of animals and plant has a definite number of chromosomes and that this number remains constant in its somatic cells, generation after generation. To keep the number constant,...

Read More

How works perform Diakinesis In the cell division - Mitosis & Meosis

The diakinesis is characterized by the disappearance of the nuclear membrane, nucleolus and completion of spindle apparatus. The separation of bivalents is completed by the process called terminalization in which the movement of the chiasmata from the centromere towards the ends of the chromosome arms take place like a zipper and at the end of diakinesis the two chromatids and held together only at their ends by the centromeres. Now the bivalents become more thickened contracted and prominently visible. Prophas I ends he...

Read More

Terrestrial OR LIthospheric Ecosystem

The ecosystem present on land or soil is called terrestrial or lithosopheric ecosystem. Terrestrial ecosystem receives plenty of light and the soil provides ecosystem nutrients water, however is limited and very unevenly distributed both in place and in time.Factors Affecting Life On Land:          Factors which influence life on land are given below:a) Temperature: Like water, favourable temperatures are very unevenly distributed on land in place and time.      On poles, the average temperature...

Read More

Division of Terrestrial Ecosystem

It can be divided into following main types such as:1-   Forest Ecosystem.      It is further sub-divided into:(a)  Tropical rain forests(b)  Temperature deciduous forest(c)   Coniferous alphine and boreal forests2-   Grass Land Ecosystem.3-   Desert Ecosystem.4-   Tundra Ecosyst...

Read More

Intervention of Man in Aquatic Ecosystem

Human activities may greatly accelerate. The process of eutrophication, because nutrients are carried into lakes from farm feedlots and sewage.          Even if solid wastes are removed, water discharges from sewage treatment plant is often rich in phosphate and nitrates dissolved from wastes and detergens.         Excessively enriched water also washes off fertilizers from fields where the mature of thousands of cattle is accumulated. These added nutrients support excessive growth of phytoplankton....

Read More

Reading Comprehension - Passage about the Pakistan food Conditions

The public distribution system, which provides food at low prices, is a subject of vital concern. There is a growing realization that though Pakistan has enough food to feed its masses three square meals a day, the monster of starvation and food insecurity continues to haunt the poor in our country.      Increasing the purchasing power of the poor through providing productive employment leading to rising income, and thus good standard of living is the ultimate objective of public policy. However, till then, there is...

Read More

Productivity of Quatic Ecosystem

The productivity, can be indicated by consumption of CO2 and evolve oxygen of photosynthesis. The productivity of aquatic ecosystem is basically determined by the light and nutrients.   Light intensity and quality varies with the water depth so, the primary productivity also varies with light.    The amount of nutrients forms also changes with season. Productivity also varies from zone to zone....

Read More

Relations between the Prophet (P.B.U.H) and the Jews - 7th Year of Hijrat

When the Holy Prophet (P.B.U.H) came to Madinah, he had made agreements with the Jewish tribes of Madinah to defend the city from foreign invaders and to maintain peace and order. But instead of defending it from its enemies, they organized a campaign of slander against Islam and its followers. They first tried to create disruption between the two man tribes of Madinah i.e. the Aus and the Khazraj. Then they incurred the displeasure of Muslims by their contacts with the Quraish of Makkah.     At the time of the Battle of...

Read More

Reasons for Change in the relationship between the Holy Prophet and the Jews

When the Holy Prophet migrated to Madinah, he sought to develop friendly relations with the Jews. For this purpose, he signed a treaty of peace and friendship with them.     The relations were cordial at the beginning, but as more and more people joined Islam, and the Holy Prophet's position grew stronger, the Jews became apprehensive of his growing and power and considered it a threat to their own dominant position in the area. Some of their learned rabbis had embraced Islam. The Jews, therefore began to deny his prophethood...

Read More

Balltle of Trench - 5th Year of Hijrat

After the battle of Uhad, the Muslims were able to regain their former position. The Quraish could not reconcile themselves with the growing power of the Muslims because they felt it was a threat to their social and religious position as well as their commercial prosperity.    The Jewish tribe of Banu Nazir who had settled at Khybaer kept on plotting against the Muslims. Their chiefs went to Makkah and asked for help against the Muslims which the Quraish agreed to give. Then they went to Ghatafan tribe and obtained their support...

Read More

Battle of Badr - Second Year of Hijrat

Causes and Events      During the first thirteen years of his mission, the Holy Prophet (P.B.U.H) had only one enemy to deal with in Makkah, the pagan Quraish, who eventually forced him to leave Makkah. But in Madinah, he had to face opposition from three quarters. First, were the Quaish of Makkah who were determined to crush the Holy Prophet (P.B.U.H) and his followers. The increasing strength of the Muslims was seen by them as a threat both to their prestige as custodians of the Ka'abah and to their social and economic ...

Read More

Year of Grief - Life In Makkah

In the 10th year of Prophet, Hazrat Khadija died. In the same year the Prophet's uncle Abu Talib too, passed away. The Holy Prophet (P.B.U.H) was so deeply grieved by the deaths of his wife and his loving uncle that this year was called Am-ul-Hazn, "the Year of Grief."      The death of Abu Talib, provided on opportunity to the enemy, to harm and persecute the Holy Prophet. The Muslims shared in his sorrow, but they were too weak to stand up against the Quraish or provide the kind of protection that he had lost due to...

Read More

Pledges of Aqabah First & Second Pledge

On his return to Makkah from Taif, the Holy Prophet (P.B.U.H) resumed his preaching concentrating more on strangers, who came to Makkah for the pilgrimage. In the eleventh year of Prophethood, six pilgrims from the tribe of Khazraj in Yasrib came to Makkah. The Holy Prophet (P.B.U.H) invited them to Islam. After hearing the teachings of Islam, they embraced the faith. When they returned to Yasrib, they introduced Islam to their friends and relatives.     In this way, the message of Islam reached Yasrib. Next year, that is,...

Read More

Migration to Yasrib - Life in Makkah

a) Causes         It was after the pledges of Aqabah that the idea of migrating to Yarib was born in the heart of the Holy Prophet, but there were also strong reasons, which compelled him to leave Makkah for Yasrib.     The people of Makkah were generally hard and ill tempered. On the other hand, the people of Yasrib were tender hearted and considerate, so Islam could find a more suitable ground in Yasrib then at Makkah in its early period of expansion.     The Holy Prophet was...

Read More

Biosphere

Biosphere is a thin layer of earth in which all living organism exist. Organisms within the biosphere not only adapt to the environment but also interact to modify and control chemical and physical conditions of the biosphere. An organism lives in a habitat.     Biosphere is spread out over the surface of planet earth extending about 8/10 kilometers in the upper reaches of atmosphere and also in same distance into the depths of oceans.     An organism responds to a variety of environment factors, and only when...

Read More

Ecological Niche

In 1917, Joseph Grinnell an American ornithologist first proposed the term niche in ecology.      Niche is defined as the ultimate distributional unit within a species is restrained by the limitations of its physical structure and its physiology. The habitat and niche the basic are closely related. Charles Eton, considered the niche, the basic role of an organism in the community what it does in and for living community, its relationship to its food and enemies. In order words he denied the niche as the species occupati...

Read More

Migration to Abyssinia

The hardships and suffering of the Muslims increased. The Holy Prophet therefore, gave permission to a group of Muslims to migrate to Abyssinia. Accordingly in the fith year of prophethood, a group of eleven men and four women secretly left Abyssinia. These included Hazrat Usman and his wife Ruqayya, daughter of the Holy Prophet (P.B.U.H). Then followed another group of seventy-nine men and seven women including Hazrat Jafar, son of Abu Talib.        Najashi, the Christian king of Abyssinia treated the Muslims with...

Read More

The Meselson Stahl Experiment - Biology

 The three hypothesis of Dna replication were evaluated by Mathew Meselson and Franklin Stahl of the California Institute of Technology in 1958.       The grew bacteria in a medium containing heavy isotope of nitrogen, N15 which became incorporated into the bases of the bacterial DNA.       After several generations, the DNA of these bacteria denser than that of bacteria grown in a medium containing the isotope of nitrogen, N14        Meselson and Stahl then, tranferred the...

Read More

Reasons for Opposition - Islam

The Quraish were leading tribe in the Arabian Paninsula. They were used to idol worship that the Holy Prophet openly condemend. They took the teachings of Islam as an insult to their religion and the ways of their forefathers.   The location of the Ka'abah in Makkah gave them an important position as the custodians of the House. It was a source of income for them, particularly the priests, as the pilgrims to the Ka'abah would being rich gifts for their idols. In the rise of Islam, they saw the danger to their dignity and prestige...

Read More

Reaction of early Muslims towards persecution

The Muslims of early days although limited in number, had very strong faith and belief in Allah and His prophet. They maintained this faith, regardless of the cosequences. For instance, the Muslim slaves who were tortured mercilessly by their masters never renounced their religion, and at times, lost their lives when given an alternative between idol worship and Islam.        The Muslims were always united under the leadership of the Holy Prophet (P.B.U.H). Even when persecutions were at their peak, instructions set...

Read More

Preaching By The Holy Prophet (P.B.U.H)

The revelations stopped for some time. The Holy Prophet passed this time in restlessness and anxiety, until one day, he saw angel Jibrael again, in the sky seated on a chair. The Holy Prophet became frightened and rushed home. He asked Khadija to cover him up. She covered him up, after which he received another revelation which said:     "O thou wrapped up (in a mantle)!Arise and deliver thy warning!And thy Lord do thou magnify." (74: 1-3)    In obedience to the command of Allah, the Holy Prophet invited his friends...

Read More

Call to Prophethood - Life of Makkah

 With age and growing understanding Hazrat Muhammad became more aware of the corrupt society around him and it disturbed him greatly. He could not believe the polytheistic ideas of the pagans of Makkah and often thought of God of his forefathers, Ibrahim and Ismail. He did not follow any particular method of worship, beacuse he was not aware of any, but he realized that there is a force of truth beyond this world which must have power and control over the whole universe.    A few years before the conferment of prophethood,...

Read More

Fruit Set & Fruit Ripening

Germinating pollen grain is not only in important structure for safe transfer of gametes and insurance for fertilization but also a rich source of auxis as well as commonly stimulating the tissues of the style and ovary to produce move auxin. This auxin is necessary for fruit set i.e. retention of the ovary, which becomes the fruit after fertilization. Without it abscission of flowers normally occurs, leading to low fruit yields.Fruit Ripening:      After fertilization the ovary and the ripe seeds continue to produce auxins...

Read More

Sex Influenced Trait - Short note

Sex influenced trait occurs in both males and females but it is more common in one sex. It is controlled by an allele that is expressed as dominant in one sex but recessive in the other. This difference in expression is due to hormonal difference between the sexes. Pattern baldness is a sex influenced trait. Many more than women are bald. It is inherited as an autosomal dominant trait in males but as an autosomal recessive trait in females. A heterozygous male is bald but a heterozygous female is not. A woman can be bald only when she is...

Read More

Reasons for Opposition - Islam

The Quraish were leading tribe in the Arabian Paninsula. They were used to idol worship that the Holy Prophet openly condemend. They took the teachings of Islam as an insult to their religion and the ways of their forefathers.   The location of the Ka'abah in Makkah gave them an important position as the custodians of the House. It was a source of income for them, particularly the priests, as the pilgrims to the Ka'abah would being rich gifts for their idols. In the rise of Islam, they saw the danger to their dignity and prestige...

Read More

Reaction of early Muslims towards persecution

Reaction of early Muslims towards persecution        The Muslims of early days although limited in number, had very strong faith and belief in Allah and His prophet. They maintained this faith, regardless of the cosequences. For instance, the Muslim slaves who were tortured mercilessly by their masters never renounced their religion, and at times, lost their lives when given an alternative between idol worship and Islam.        The Muslims were always united under the leadership of the Holy Prophet...

Read More

Discovery of Electrons - Cathode Rays of Properties

Discovery of Electrons:      At ordinary pressure the air inside the Discharge Tude do not conduct electricity even when the electrodes were connected to a source of very high potential of about 5000 volts.     If the pressure inside the tube is reduced and a high voltage of 5000 - 10000 is applied, an electric discharge is produced through the gas producing a uniform glow inside the tube. By reducing the pressure in the tube still further to about 0.01 tor thr original glow disappears. Rays are produced...

Read More

Metabolism - Ananolism - Catabolism - Water

Metabolism:    All the chemical reactions taking place within a cell are collectively called metabolism. Metabolic processes are characterized as anabolism and catabolism.Anabolism:        Those reactions in which simpler substances are combined to form complex substances are called anabolic reactions. Anabolic reactions need energy.Catabolism:         Those reactions in which complex molecules are broken down into simpler ones are called catabolic reactions. Catabolic reactions...

Read More

Reading Comprehension - Passages - Practice With Exercise

Democratic societies from the earliest times have expected their governments to protect the weal against the strong. No 'era of good feeling' can justify disc haring the police force or giving up the idea of public control over concentrated private wealth. On the other hand, it is obvious that a spirit of self denial and moderation on the part of those who hold economic power will greatly soften the demand for absolute quality. Men are more interested in freedom and security than in an equal distribution of wealth, The extent to which Government...

Read More

Genetic Engineering Of Plants

  Today it is possible to directly alter the genes of organisms. Transgenic plants carry a foreign gene that has been introducted other into their cells so that they have new and different traits.        Cotton, corn, potato and soybean plants have been engineered to be resistant to either insect perdition or herbicides that are judged to be environmentally safe. Some corn and cotton plants have been produced that are both insect and herbicides resistant. In 1999, transgenic crops were 'planted on more than...

Read More