•  The heat of vaporization of water is expressed as the calories absorbed per  gram of vaporized water.

•  It is a bond by which amino acids are linked together. It is formed by amino group of one amino acid and carboxyl group of the adjacent one.

•  The temperature of the remaining 998 ml of water will be lowered by 1 C. 

•  Anabolism is the sum of reactions in which simpler substances are chemically combined to form complex substances. Catabolism is the sum of reactions in which complex substances are broken down to simpler ones so as to release energy.

• The water molecules give rise to H+ and OH ions.

• How are the four bonds arrangzed when a carbon atom combines with four atoms or radicals of some other elements?

•  The four bonds are arrangedsymmetrically in a tetraheddron.

• The percentage of water in human bone cells is 20% and in brain cells is 85%.

• The specific heat capacity of water means the number of calories required to raise the temperature of one gram of water to 1 C.

•  The micromolecules of cellulose are glucose molecules; of Fat are fatty acids and of protein are the amino acids.

• carbon is the basic organic componds..

• The covalent bond stores large amount of energy. 

•  The amount of water in different organisms varies from 65 to 89 percent.

•  A reaction between a compond and water, Particularly the one involving H+ and OH ions is called hydrolysis.

•  Substrate is the substance on which enzyme acts

Or

• Substrate is the non-living material on which an  organism lives or grows.

• Prosthetic group is the non-protein part of an enzyme which is covalently bonded to the proteins (enzyme).

• The Co-enzyme is the non-protein part (co-factor_ of an enzyme, if it is an organic compound.

•  The detachable co-factor is known as an activator, if it is an inorganic ion.

•  Active site is the small protein of the enzyme to which is its catalytic activity restricted.

•  The enzyme is a proteinaceous compound that catalyses biochemical reactions.

• The Biochemical reactions would operate but at such a show speed that life would be impossible.

•  some enzyme require a co-factor for their proper functioning.

•  The define regions are the binding site and the catalytic site.

•  The enzymes are found in the mitochondria.

•  An enzyme whose cofactor has been removed, rendering it catalytically inactive is known as an Apoenzyme. When Apoenzyme is combined with its co-enzyme, it forms a Holoenzyme (Complete enzyme).

• The cofactor is a non-protein substance that helps an enzyme to carry out its activity.

•  The active  site of the enzyme is a threee dimensional cavity bearing a specific charge by which the enzyme reacts with its substrate.

•  The increase in the substrates PH, temperature and concentration within certain limits increases the rate of operation of the enzyme.

•  Robert Hooke used the word "Cell" in living beings in 1665.

• This was said by a German Physician  Rudolp Virchow.

• Lamarck said in 1809 "No body can have life, if its constituent parts are not cellular tissue or are not formed by cellular tissue.

•  Egg of the ostrich is the largest cell in this world.

•  Phloem cells transport food in plants.

• The sclarenchymatous cell provide support  to plants.

• The cell is the unit of the structure and functions of the body organization of the living beings.

•  The living things are chemical organization composed of cells and capable of reproducing themselves.

• All organisms are composed of one or more cells.

    All cells arises from preexisting cells.
    Cell is the basis structural as well as functional unit for all organisms.

•  Virus can  be defined as a non-cellular infectious entity which contains either RNA or DNA normally encared in protein coat and reproduces only in living hos   t cells.

• .The scientific names of onion is allium cepa: of amaltas is cassia fistula : of man is Homo sapiens:of potato is solanum tuberosum and of tomato is solanum esculentun.

• .Edward jenner introduced the technique of vaccination in 1796.

• The ate the phylum class, order , family genus and species.

• The viruses that live as parasites in the becteria are called bacteriophages.

• The first part of the scientific name represents the genus and the second part represents.

                                         Or

• The firs part of the scientific name is the generic name and the second part is the specific name.

• Species is a group of individuals which resemble with one another and can freely breed among themselves in nature to produce fertile offspring.

• Kingdom Monera includes prokaryotic unicellular organisms such as bacteria.

• Robert whittaker distinguished fungi as a separate and independent kingdom in 1969.

•  Rabies is a madness disease which is transmitted to human beings by the bite of rabid dogs, foxes, cats, bats and some other animals.

• Robert Koch formulated "green theory of disease".

• Some members of the genus Mycoplasma are the smallest bacteria which are about 100 to 200 nanometer  in diameter.

•  These are the Cocci . bacilli and spiral.

• The bacteria which exist in a variety of shapes are known as polymorphic.

•  The arrangements are diplococcus, streptococcus, tetrad , sarcina and staphylococcus.

•  The arrangement is called diplobacillus when bacilli occur in pair.

• The examples of cocci are diplococcus pneumoniae and staphulococcus aurous whereas those of bacilli are Escherichia coli, Bacillus Subtilis and pseudomonas.

•  The Vibro is curved or comma shaped rod;  spirillum as spiral while spirochete is a thin flexibel spiral.

• The name Epulopisium Fishelsoni, it size is 600 um by 80 um.

• The Bactria are found in the air, on land,  in the soil, in water in oil deposits, in decaying organic matter and in the bodies of plants, animals and man.

•  The are the preparation of vaccines for the diseases anthrax, fowl cholera and rabies (hydrophobia) introduced of pasteurization process and development of fermentation industries.

• The ciliates have two kinds of nuclei smaller one or more diploid micronuclei and a larger polyploid macronucleus. The former function is sexual process and the letter control cell metabolism and growth.

•  Green algae are the ancestors of green plants.

• The zooflagellates may be free living symbionts or parasites.

•  Plasmodium is a feeding stage of slime mould which is in the form of a multinucleate mass of cytoplasm that can grow to 30 cm.

 

•  Some red algae incorporated calcium carbonate in their cell  walls from the ocean and take part in building coral reefs along with coral animals.

• The giant amocbas get energy From methanogenic (which from merhane) bacteria while live within their bodies.

Paragraph on Quaid-e-Azam

Quaid-e-Azam was born in Karachi on 29 December 1876. His Father name Jinnah Punjab. He has Completed his education first at Karachi and then in England. On his return to India his started his practise as a Lawyer He was efficient person. He joined the Indian National Congress but soon left it and Joined the Muslim League with his great and wish Leader ship, He started log and hard campaign to get a separate home land from the Muslim. Finally he had succeeded it on 14th August 1947. a newly created name Pakistan. Quaid-e-Azam became his first Governor General unfortunately only after twelve months of creating of Pakistan Quaid-e-Azam died on 11 September 1948

HEAT:
        Heat is a form of energy. It flow from hot body to cold body.
The flow of heat stops when the temperature of two bodies is ame. The bodies are said to be in "THERMAL EQUILIBRIUM" .
        The heat lost by hot body is equal to the heat gained by the cold body. This is known as "LAW OF HEAT EXCHANGE".

          Mathematically,

                              ΔQ  = ΔQ  

                                                     Lost     Gained  

UNITS:-
          The heat is measured in joules (J), Calorie is old unit of heat.
                                  4.2 cal  =  1j.
TEMPERATURE:-
                             The temperature determines the direction of the flow of heat. When , two bodies are brought in to thermal contact.

THERMOMETER

It is an instrument which is used to measure the temperature . It consists of a capillary glass tube, having bulb at the one end. The bulb is filled with mercury, the melting of ice and boiling point of water are marked on it.

Scales of temperature 

The following on the scales of the temperature

1) Celsius - OR Centigrade scale:-

                                                         In this scale the melting point of ice is snaked at '0' and boiling point of water is marked at '100'. The interval b/w these two fixed points it in divided into hundred (100) equal parts each part is called centigrade degree (1°C)

Fahrenheit Scale:-

                              In this scale melting point of ice is marked 32 boiling point of water 212. The internal is divided into 180 equal parts.

        The centigrade scale and Fahrenheit scale are related as

                        C   =  F - 32 

                        100        180

      OR             C  =  F - 32

                         5          9

3) Kelvin Scale -OR- Absolute scale:-

                                                            In this scale the melting point of ice is marked 273 and boiling point mete   r marked 373, the internal is divided into 0 equal parts, this means that the magnitude of Celsius degree and kelvin degree is same

                   They are related as

                                                   K°= °C+273.

Relation b/w Kelvin and Fahrenheit scale is

                                                   F° =  5°C (F-32) =273.

  All the following three scales of temperature are gives as the following figure.

                          °C            F°            K°    

                          100        212           273

                    ⇧        ⇧          ⇧ 

                   100     180       100

                      

                                       

                         ↓         ↓              ↓

                        0         32          273.

                   

     

            

                                                                       

STOPPING BY WOOD ON A SNOWY EVENING "Summary"

This poem is written by the American poet Robert Frost. He was born in San Francisco, California on 26 March 1874 . He died on 29 January, 1963 in Boston  Frost used in his poetry, the language of everyday life and depicted scenes from the Common man's experiences and from Country life. He received many honours for his poetry.
In this Poem the poet describes the scene of forest in winter reason he  known the owner of the forest who lives in the Village.
               The Poet is siding a horse. He stops to watch and enjoy the beauty of snow flakes Falling. These near by.
                 It is the darkest evening Instinctively the house shake its bells, fined on its strips, us if to enquire here is no danger to stop at a lonely place on the darkest evening the was on other sound except the sound of soft wind and falling of the ting flakes.
                 The Poet finds the forest very lovely dark and deep. He want to stay and enjoy the beautiful scenes but he has to Leave the place because he has a long distance to cover to reach his destination before the might falls.

Children "Summary"

This touching and Lovely Poem "Children" written by Henry Long Fellow. In this poem the poet describes his feeling towards children and Calls them to him so that he may enjoy their company. He says that the time and age bring Knowledge and wisdom. to a person, but they also bring along worries and troubles, He Compare himself to Children's happiness. The children are source of joy and Pleasure to the poet. He wants to get pleasure and company of children in order to forget his worries, The Poet  think that without children the world would be useless, dark and value less . He says that the Children are better than all the Poems that have ever been written.

The Daffodils "Summary"

"The Daffodils" Composed by "William words worths. He was a famous English Poet and is remembered as the poet of "Nature"
"The Daffodils are beautiful yellow flowers, which grow in the English Country side. It comes into followers in early spring. In this poem he says that one day as he was walking alone by himself all of a sudden he saw a beautiful seen of a large number of "Daffodils growing under the trees and the side of the lake. The seen of the take was so charming that the poet hearth was filled with joy.
The seen of these Golden Daffodils after comes to his memory and fills his heart with joy and happiness.

The Last Sermon Of The Holy Prophet (Peace be upon him) "Summary"

Hazrat Muhammad (Peace be upon him) the prophet of islam, was born in 571* A.D at Makkah. He belonged to the noble family of Quraish. Hazrat Muhammad (Peach be upon him) asked the Quraish not to worship their false God. He told them to worship the one and the only true God. Most of them refused to accept Islam . Their opposition to Islam become so fierce and terrible that he had to ask the believer to migrate to Medina. In 622 A.D the Prophet (Peace be upon him) himself accompanied by his faithful friend Hazrat Abu Bakar, migrated to Medina. This event is known in history as the "Hijra".

In Medina, the Prophet (Peace be upon him) founded an Islamic Society, based on the three principles, that all Power belongs to God. Muhammad (Peace be upon him) is his Prophet, and all Muslims are brothers to one another. In the 10th years of Hijra, the Prophet together with his followers went to Perform Hajj at Makkah. on this historic occasion he addressed a very large gathering of Muslims on Mount Arafat.

Although the Prophet (Peace be upon him) is no more with us, we have the Holy Quran to give us guidance. We should read it daily and try to understand what it teaches.

THE MAN OF LIFE UPRIGHT

 REFERENCE: These lines have been taken from the poem, "THE  MEN OF LIFEUPRIGHT", written by Thomas Campion.

context:            The poem is simple in language but packed with deepest meaning. The words are beautifully chosen and are related to the subject. A noble man owns virtues of body and soul. He is honest, simple, sincere and religious. He leads strictly honourable and honest life. He seeks guidance from heaven and keeps himself away from the worldly wishes.

CANCER

            Uncontrolled, rapid amitotic proliferation of cells of the body is termed as cancer. The cancer cells exhibit less adhesion with other cells and show great motily.Thiscould be the result of mutationinthe genes regulating growth and mitosis.The persons exposed to some specific chemicals such as alcohol, tobacco, etc, ultra violet radiation. ionizing radiation, etc have great risk of development of cancer. In animal some viruses or frequent injury to a certain point may develop cancer.
               The cancerous cells complete with the normal cells for nutrition. Since they divide rapidly and indefinitely so the normal cells are deprived of the food and as a result start dying.

MEIOSIS (REDUCTION DIVISION)

                 The term meiosis (Gr, meion - to reduce)   was coined by J.B Farmer (1906). It takes place only in GERM CELLS. By the process of this division the number of chromosomes of the germ cell reduce to half, so the resulting cell (gametes in animals whereas spore in plants) have HAPLOID number of chromosomes. The fusion of haploid male and female gametes result in a cell called as ZYGOTE. It has same number of chromosomes as the parent germ cell.
Process of meiosis
       
           The meiotic division includes two complete divisions.

FIRST MEIOTIC (HETEROTYPIC) DIVISION:

              This is the first meiotic division and starts after an interphase. It consists of the following four phases.
PROPHASE-I
            This first prophase is the longest stage of meiosis. It includes the following substages.
(i) Leptotene:
          In this sub stage, the chromosomes are extremely thin, long, uncoiled, slender, thread-like structure. This stage resembles with the early mitotic prophase except that the chromosomes are longitudinally single instead of double. During this stage the chromosomes become more uncoiled and take up a specific oriebtation (to give a new direction) inside the nucleus. The chromosomes show beaded structure. CHROMOMERES at irregular intervals along their entire lenght. The centriole duplicates and each daughter centriole migrate towards opposite poles.

(ii) Zygotene:
              During this stage, homologous chromosomes are attracted toward each other to form a BIVALENT. This process is called as SYNAPSIS. The homologous chromosomes touch at each other at one or more points along their entire lenght.


(iii) Packytene:
              During the pachytene sub stage, the pair of chromosomes become twisted spirally around each other and more readily distinguishable. Later homologous chromosomes start splitting lengthwise so that each pair consists of four chromatids known as TETRADS.


(iv) Diplotene:
               During this sub stage an important genetic phenomenon called as CROSSING OVER takes place. It in volves reshuffling, redistriution and mutual exchange of hereditary material of two homologous chromosomes. The point of contacts and interchange between two homologous chromosomes is called CHIASMA or CHIASMATA. The nucleolus remains prominent up to this stage.


(v) Diakinesis:
               During this stage, the bivalent chromosomes become more condense and evenly distributed in the nucleus. The nucleolus and nuclear membrane disappear. The chiasmata move from the centromere towards the end of the chromosome so the intermediate chiasmata diminish. The chromatids still remain connected by the terminal chiasma and these exist up to the metaphase. Finally the bivalents appear to be thicker so they are become more prominent.

METAPHASE-I
            The bivalents get arranged themselves at the EQUATORIAL PLANE in a way that their centromeres are attached to the spindle fibers. Now the bivalent chromosomes are ready to separate.

ANAPHASE-I
             This is the actual reduction stage. Due to the disassembly of the chromosomal fibers, each homologous chromosome with its two chromatids and undivided centromere move towards the opposite poles. This stage lasts till they are reached at their respective poles.

TELOPHASE-I
              As soon as the chromosomes reach their respective poles, a nuclear membrane is formed around them. The two daughter nuclei are formed. The chromosomes now become uncoil and the nucleolus reappears. After a brief interphase, the two daughter haploid cells proceed to the second meiotic division.

SEOND MEIOTIC (HOMOTYPIC) DIVISION:

               The second meiotic division is also known as the HOMOTYPIC DIVISION. This is actually mitotic division which result in four haploid daughter cells. It consists of following four phases.

PROPHASE-II
                The centrioles duplicate to form two pairs of centrioles so that each piar move towards the opposite pole consequently forming "spindle". The nuclear membrane and nucleolus disintegrate.

METAPHASE-II
                 The chromosomes arrange themselves at the equatoial plane. The centromere of each diad becomes attached with a chromosomal fiber of spindle. They are now ready to separate from each other.

ANAPHASE-II
                  The chromatids of each diad begin separating and keep moving towards the opposite poles eventually touching it. As soon as they are completely separated from each other, they are termed as MONADS.

TELOPHASE-II
                     In the telophase-II a nuclei membrane is formed around them. The chromosomes become uncoil and diffused. CYTOKINESIS follows producing four daughter haploid cells.


Significance of Meiosis

1. ) Meiosis maintains constant number of chromosomes in sexually reproducing organisms.
2. ) By crossing over, meiosis provides an opportunity for the exchange of genes and thus causes the genetical variations among the species. The variation are the materials of the evolutionary process.

CELL CYCLE

It is a series of processes by which cellular material is divided between daughter cells. It consists of a division and non-division phase of the life cycle of cell.

INTERPHASE

             The phase between the two division is called INTERPHASE. During this phase the nucleus and cytoplasm remain metabolically active and due to that an increase in the volume of the nuclear as well cytoplasmic substances takes place. It meludes the synthesis and organization of the substrate and enzyme necessary for DNA synthesis. It is the longest phase of cell cycle. Interphase is divided further into further three sub-stages. G1(gap), S(synthesis) and G2(gap two) phases.

G1 phase 
           During G1 phase, the synthesis and organiztion of  substrate (RNA) and the synthesis of enzyme for DNA  synthesis takes place. In the end of G1 phase the cell either may enter a resting phase or G0 (resting phase) or into S phase. The chromosomes occur in the form of long, diffused coiled and indistinctly visible chromati fibers. The size of the nucleus increased greatly due to accumulation of rRna and ribosomal proteins.


S pahse:
          During S phase of DNA occurs to replicate the genetic material A daughter pair of centrioles is originated during S period hear the already existing pair of centrioles.

G2 phase
           During the G2 sub stage, the ribosomes and spindle formation occurs

CELL DIVISIONS
      There are following three kinds of cells divisions takes place in animals and plants cells. Amitosis, Mitosis, and Meiosis.

AMITOSIS

        It is also called as DIRECT CELL DIVISION because  there are no spindle formation as well as other nuclear and cytoplasmic events. Simply, the nucleus elongates. a constriction appears which gradually deepens. Finally , the nucleus divides it into two halves, each of which contains a daughter nucleus. In this way two daughter cells are formed.
                Sometimes, the nucleus divides into two unequal parts. this is called as NUCLEAR BUDDING. But sometimes, nucleus divides into numerous equal parts this is termed as NUNLEAR FRAGMENTATION. in either case , each daughter nuclei gets equal amount of the parent cytoplasm and forms a daughter cell.
                 Amitosis takes place in unicellular organisms like protozoa,  bacteria. abnormal diseased tissues such as tumor, cancer and also tissues.


Cell Death (Necrosis and Apoptosis)
The death of the cells in higher organisms is due to either two processes, necrosis and apoptosis.
NECROSIS: Due to injuries, the death of the cells is called necrosis. As a result. the damaged cell ruptures and releases the toxins on side, which causes inflammation of the neighboring cells
APOPTOSIS: It is  also called "programmed cell death". It is proposed that the dying out cell gives some biochemical signal to phagocytes for autophagy. Thus the neighboring cells are least affected in this way. It is commonly observed in ebbryonic development of multicellular organisms where autophagy of many cells is required. It is also seen in the cells which have potential to become tumor.. 

MITOSIS

          It is also called as INDIRECT CELL DIVISION. It takes place in similar way both in animals and plants. As a result of mitosis. a parent cell gives rise two daughter cells having the same number of chromosomes  as the parent cell.
           It is a process but for the convenience it is usually divided into following four stages or phases; prophase, metaphase, anaphase and telophase.

PROPHASE (Gr. Pro - before; phasis - appearance):  It is the longest phase of mitosis. The beginning of the prophase is marked by a condensation of the very thin chromatin threads to form rod-like structure which are the duplicated chromosomes. Each prophase chromosomes is composed of two coiled filaments, the "SISTER CHROMATIDS". In each chromosomes there is a constriction called as CENTROMERE. The sister chromatids becomes thick and short. The nuclear membrane and nucleolus start disintegrating. The centrioles self-duplicate. separate and move to opposite sides of the cell. There also appear in the cytoplasm some translucent fibers that eventually stretch between and connect with the two sets of centrioles, forming a structure known as MITOTIC SPINDLE. The spindle consists of three kind of fibers, continuous fibers running from one pole to another, discontinuous or half fibers which from pole to the equator and astral fibers which arise from the centrioles. In higher plants, the spindle appears directly at the poles.

METAPHASE:

           It is the shortest phase. Formation of spindle gives the cell an orientation: the centrioles forms the poles and "a plane biseeting the spindle in the equator" which marks the plane of division or cleavage. The chromosomes become attached to discontinuous spindle fibers by their kinetochore of centromeres fron the EQUATORIAL PLATE or METAPHASE PLATE. 

ANAPHASE:

           It begins with the separation of two centromeres of each and every chromosome. The centromeres move a part and chromatids separate and begin their migration towards poles. Because they are how single threads with their centromeres. the chromatids are termed as CHROMOSOMES. Since each chromosome contains one chromatid, it is called MONAD. The end of the anaphase is marked by the reaching of the monads at the respective poles.

TELOPHASE:

          During  this phase, there are two clusters of chromosomes, each cluster containing exactly the same chromosomes as the other. The chromosomes starts to uncoil and becomes less and less condensed, gather into masses of chromatin which becomes surrounded by discontinuous segmentsof nuclear envelope. In this way two daughter nuclei are formed. At the finalstage nucleolus reappears. The high viscosity of the cytoplasm,characteristic of the metaphase and anaphase decreases.

CYTOKINESIS:

           By the process of CYTOKINSIS (division of cytoplasm) two daughter cells are formed. In case of animal cell, a constriction appears in the equatorial plane which gradually deepens to divide the cytoplasm into two equal halves. In case of plant cells, a cell plate is formed in the cytoplasm which divides the cytoplasm. 

Significance Of Mitosis: 

1. ) It provides the opportunity increasing the number of cells during development and growth of organs and body of an organism.
2. ) Mitosis help the cell in maintaining its proper size.
3. ) Due to mitosis old decaying and dead cells are replaced by new cells.
4. ) Through mitosis and equilibrium is maintained in the amount of DNA and RNA contents.

PLANT HORMONES

Certain substance affect growth, they are called plant hormones or phytohormones and also termed as growth regulators . Growth hormones may be defined as . "They are synthesized in young embryonic tissue as there is no specific organ for their production in plant. they are transferred to other cells where they are required and influence the process of development . There are five kinds of plant hormones.

1.Auxins: 

                 Auxins are compound ,which induce elongation in shoot cells and other growing parts. Auxin is a class of chemicals both naturally and synthesized ones . Indole acetic acid (1AA) is the naturally occurring auxin of higher plants. It is synthesized at the apices of stem and root (apical meristem), young leaves and young embryo within seed . Synthetic chemicals having effect like auxin are indole butyric acid (IBA) and naphthalene acetic acid (NAA).

            Auxins were first collected from oat plant.Fritwent  (1926) was first to use term auxin. He reported his activity in oat plant. Went (1928) was other scientist who performed oat-curvature test.

Role of Auxins: Some important roles of auxin are as follows:
(a) Cell division and cell elongation : Auxin take part in the cell division and cell elongation at the apices of root and stem.so their length is increased. It also helps in the  cell division of cambium to produce vascular tissues and to increase the width of plant body.
(b) Initiation of  roots: Auxin helps in root formation It also produces adventitious roots from the base of stem.
(c) Abscission of leaves and fruits: When leaves and fruits are mature, auxin production is stopped and at their lower region a layer of cells is formed called abscission layer, due to the jerk the leaves and fruits fall on the ground.
(d) Growth of fruit:  Auxin produced in young embryo promotes the growth of fruit.
(e) Parthenocapy : Use of auxin also helps in producing fruits and seeds without fertilization.
(f) Apical dominance :Auxin  helps in the rapid growth in the apical region of stem and root, it is called apical dominance.
 (g) Weedicide: Auxin  are selective weed killer. 2-4-dichlorophenoxy acetic acid (2-4-D) is used to kill weeds in lawns and central crops.

 2. Gibberellins:
                       It is group if chemicals that promote cell division and cell elongation . It is an important growth hormone of plant. First noticed in Gibberella fujikurel fungus which infected rice seeding and produced a disease called bakanae (Foolish seeding ). They infected seeding elongated and ultimately fell over without  producing grains. Two Japanese scientists T-Yabuta and T .Hayashi succeeded in isolating the active substance from the fungus and was named Gibberellin, after the name of genus . Soon after its 70 different types of Gibberellin have isolated from the higher plants. They are named as A1, A2, A3 to A70.

Role of Gibberellins:
                     Giberellins prevent the genetic and physiological dwarfism in plants. Gibberellins are found to be effective in braking the dominancy. They induce flowering in long day plants.In some cases these hormones help in fruit formation by 
  Parthenocarpy. They promote cell division and cell elongation of stem and leaves. They slimutale gemination of pollengrain and formation of pollen-tube in many plants.

3.Cytokinins:
           These are a group of substance both natural and synthetic , which react with auxin to induce cell division Miller (1954) isolated it from herring sperm DNA and named  it as Kinetin. Cytokinin have been extracted from coconut milk, tomato juice ,fruit of pear , plum ,yeast, maize and other plants. The cytokinin of maize grains is called zeatin.
Role of Cytokinin: It takes part in cell division in the presence of auxins. It is involved in the elongation of cells. It initiates the growth and root formation. It breaks dormancy. It indices flowering in short day plants. It delays senescence that is old age and detachment of leaves from plant.

4. Abscisic acid:
      It does not take part in growth of plant body, but during unfavourable conditions it reduces or stops the growth. It is called stress hormone. In dry season and cold weather it stops the formation of buds and seeds, causes stomata to close, modifies leaves into scales which protects the buds and increases the process of leaf fall.

5. Ethene: 
It is gas but it work as hormone. It is called ripening hormone. It takes part in the ripening of fruits. It effects permeability of cell membrane, which allows enzymes responsible for destroying chloroplast with the result that red and yellow colours are unmarked and fruit assumes ripened colour. It takes part in the abscission of leaves. It induce flowering in some parts, such as pineapple.

SUPPORT IN PLANTS

Root and shoot are two major parts of body of higher plants. They are identified on the basis of morphology and physiology. These plants require some special tissue, which are present in their whole body. Young stem has outer-layer called epidermis. Beneath epidermis cortex is present and central portion called stele vascular tissues. This type of stem depends for its mechanical support on the following tissues:

• Thin walled parenchyma-having turgidity.
• Thick walled living tissues collencyma and dead tissues like scelerenchyma.
• Stele as cylindrical core of vascular bundles.

Parenchymatous tissues are found in epidermis, cortex and pith. Bryophytes are made up of these tissues. Parenchyma are turgid, exert and internal pressure called turgor pressure.

Collenchyma is another type of simple tissue important for the support in plants. They perform functions of support in young plants and in older plants in stem and leaves.

Scelerenchyma tissues are mostly dead on their maturity. Tracheids are found in the xylem while vessels are long tubular scelerenchyma cells join end to end to form long water conducting pipe in xylem. Fibers and sclereids are two types of scelerenchyma cells. Fibers are tough and strong, but flexible while sclereids are variable, mostly irregular in shape. Sclereids are formed in nuts and hard parts of seeds. The simple unbranched sclereids are generally called stone cells. Jute and hams having fibers of scelernchyma cells, which are used for making ropes.

Significance of secondary tissues:

              Tissues formed by the activity of vascular cambium and  cork cambium are called secondary tissues. it takes place most in dicot and rare in monocot species. The cambium cells within the vascular bundles are called fusiform intials. The part of ring where changes occurred called heart-wood. Whereas outer part is called sap-wood. For the protection of exposed tissues and to increase in diameter, a layer of meristematic cells the cork cambium or phellogen, arises in the cortex. They deposit a waxy material called suberin in their walls  and then die. Masses of loose cells, through which gases and water vapours readily pass out are known as lenticels. Secondary growth requires more water, minerals and food conduction for growing plant hormone control and coordinate the plant responses in two ways:

1. Hormones control movement and various metabolic process in plants.
2. They control growth in different parts of plants body.

Plant movement:

         In plants there is no proper and distinct movement like animals, but in their body growth of certain organs, curved growth and bending processed are considered as movement. The movement of plant occurs in response to certain stimulus, in a particular direction of that stimulus. Such responses are called tropism. Tropism is a Latin word, which means turn of body part. There are three kinds of tropism:
   

       1.Phototropism:  It is movement of plant towards light.

       2.Geotropism: This movement is due to force of gravity.

       3.Thigmotropism: This movement is due to touch of plant body.

 

 Biological clock and circadian rhythm:  

 There is a particular clock system in plant and animals, which control physiological and metabolic functions according to time. It is known as biological clock. Movement of plant organs due to light & temperature are controlled by it.

      Performing of function by living organism according to a particular time called biological rhythms or biorhythms. When this process is repeated after 24 hours is known as circadian rhythms. The circadian rhythm in plants is independent of climatic meters, such as in Bean plant sleep movement occurs in the presence and also in absence of light,
                   In Oat (Ararot) plant growth is by biological clock and in Bryophyllum plant CO2 metabolism takes place by biological clock.
        In plants when all function and movements are controlled by internal biological clock system, then these are called endogenous rhythms.
         This clock system is not changed umtil some abnormal change takes place in body of living organism.

 Photoperiodism: 

                  The period or lenght required by plant body to increase the ability for growth, production of fruits and seeds is called photoperiodism. It may also be defined "response of plant to relative period or lenght of the day and night." The light period is different in different plants.


5. Response to environmental stresses:
                 The unfavourable conditions of environment are called environmental stresses. Water, light, temperature, CO2 and other substance are necessary for the plants, when there is shortage of these essential substances, the plant face great difficulty, when their functions. the environmental stresses for plants are as follow:

1. )  Water shortage or drought conditions
2. )   Less supply of O2
3. )   High concentration of salts in soil
4. )   High temperature 
5. )   Herbivory / over grazing