Inflorescence - Racemose Inflorescence - Cymose Inflorescence & Alternation of Generation

It is the mode of branching of floral axis having a group of flowers. There are two types of inflorescence.

Racemose Inflorescence: 

    It is indefinite inflorescence. In Racemose, man axis called peduncle continues to grow. The flower develops in acropetal in acropeta succession. It means the old flowers are at the base while young flowers are at the tip of floral axis. The opening is centripetal.

Peduncle Elongated: 

• Racemose : It is an inflorescence in which flowers are pedicellated and bisexual. e.g. Brasica.
• Spike: It is an inflorescence in which flowers are sessile and bisexual. e.g. Amaranthus.
• Catkin: It is an inflorescence in which flowers are sessile and unisexual. e.g. Mulberry.
• Spadix: In this case flowers are covered by one or many large bracts called pathes.

Peduncle Shortened: 

• Corymb: It is an inflorescence in which flowers have pedicle of unequal length. The lower flower have long pedicle and upper have small pedicle so that all flowers are at the same level. e.g. lbreis.
• Umbel: It is an inflorescence in which all flowers have pedicle of same length, the pedicles appear to rise from common point. e.g. Coriander.

Peduncle Flattened: (head) (Capitulum)

     It is an inflorescence in which peduncle is flattened laterally expanded, with growing point in center. It has a mass of small sessile flowers called florets. It has one or more whorls of bracts at the base forming an involucre.

Florets are of two types.

• Ray Florets: These florets are strap shaped and are present at the margin.
• Disc-Florets: These florets are tubular and are present in the center. e.g. Sunflower, Zinnia, Marigiod etc.

Spikelet Inflorescence: This kind of florescence is found in many plants. It is a kind of racemose inflorescence. There are three bracts at its base called glumes. The lower two glumes are without flowers are called empty glumes. The third glume has flower in its axil and is called lemma. Just opposite to lemma there is small bractole called palae. Flowers are covered by their lemma and palea e.g. Wheat, rise, Coat etc.

Cymose Inflorescence

  In cymose inflorescence main axis soon stops growing i.e. it grow to a certain height. The flower develop in basipetal succession i.e. oldest flowers are at tip and young flower are at the base. The opening of flower is Centrifugal.

1. Uniporous Cymose: The main axis soon ends into a flower and producing only one lateral branch at a time ending in a flower. It has only two types.
2. Scorpioid Cymose: If successfully branches are produced on alternate side is called Scorpioid Cymose e.g. Cotton, Forget-me-not.
3. Helicoid Cymose: If the succeeding branches are produced on same side, it is called helicoid e.g. Sundew.
4. Biparous Cymose: The main axis soon ends into a flower and producing two flowers, this mode is followed by each succeeding flower. e.g. pink-night-jasmine.

Alternation of Generation

   In plants there are two generations called sporophyte and gametophyte. During life cycle of plant, sporophyte form gametophyte and it forms sporophyte, this is known as Alternation of Generation.

   Only in bryphytes the main plant is gametophyte, while in all other plants sporophyte is main plant while gametophyte is reduced.

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Short Notes on Structure of Mature Seed

Structure of Mature Seed:

      After double fertilization ovule develops into seeds. During the last stages of seed maturation the water is lost by dehydration. The mature seed contain 5% to 15% water by weight. The embryo stops growing and developing until the seed germinates. Embryo is surrounded by cotyledons (Seed leaf) or endosperm or by both.

      Both endosperm and embryo are enclosed in seed coat, which is formed by ovule integument. If a seed has single cotyledon it is known as monocot. The embryo is in the form of axis. The part of embryo above the cotyledons is called epicotyl. At the tip of epicotyl there is plumule, which will develop into shoot. The part of embryo below the cotyledons is called hypocotyl. It has redicles at its tips, which will develop into roots. The seed of monocot has single cotyledon e.g. corn, wheat, rice and other member of grass family. The cotyledon is shield like and is called scutellum, it absorbs nutrients from endosperm during germination. The embryo of grass seed is enclosed by two sheaths. The sheath covering the roots is called colerhiza. The shoot is covered by coleoptile.

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Salient Feature In The Life Cycle Of Gymnosperm

These plants that produce necked seed are called gymnosperm. The fruit is not formed because ovary is absent.

1. The main plant is diploid and a sporophytes.
2. The plants produce two different types of spores micro spore and mega spore, this condition is called heterospory.
3. The functional mega spores develop to form a reduced female gametophytes, which remains within mega sporangium.
4. Female gametophytes consists of two to five archegonia each having single ovum.
5. Each micro spore develops to form a reduced male gametophytes, which consists of stalk nucleus, tube nucleus, two male gametes and two prothalial cells within an elongated pollen tube.
6. Fertilisation takes place within sporophytes.
7. After fertilisation mega sporangium form seed.
8. Seed undergoes epigeal gerimnation and forms new sporophytes plant.

Sexual Reproduction In Flowering Plants:

   A flower is a modified reproductive branch. A flower consists of four floral leaves. They are sepals, petal, stamen and carpals. The sepals and petals are non-reproductive leaves. The stamen and carpals and reproductive parts of plants.

Stamen: Stamen is male reproductive part of flower. It consists of two parts, anther and filament. Anther consists pollen Sac, which contain pollen grain or micro spores.

Carpels: It is female part of the flower. It consists of three parts stigma, Ovary, and Style. Ovary consists ovules.

Complete Flower: If one or more floral leaves are absent in the flower it is called incomplete flower.

Bisexual Flower (Hermaphrodite): If both stamens and carpels are present in same it is called bisexual flower.

Uni sexual Flower: If a flower has either stamen or carpal it is called uni sexual. If flower has only stamen it is called staminate. If flower has only carpals it is called carpel late.

Monoecious: If staminate and carpel late are present in same plant, this plant is called monoecious e.g. Corn.

Dioecious: If staminate and carpel late flower are present at different plants then these plants are called dioecious. e.g. date palms.

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What is Pollination & Role of Pollen Tube

The transfer of pollen grains from anther to stigma of a flower is called pollination. Pollination is two types.

1. Self Pollination
2. Cross Pollination

Self Pollination: Transfer of pollen grain from anther to stigma of same flower is known as self-pollination. In this type only single flower is involved. Deocious plants cannot self-pollinate because they are uni sexual, being either staminate or carpel late.

Cross Pollination: Transfer of pollen grain from the anther to stigma of another flower of same species. Cross-pollination takes place by different agents like wind, water, insects and animals. In cross-pollination two flowers involved.

    When pollen grains reached to stigma after some rest they begin to germinate. The outer layer of pollen grain (exine) bursts and a pore from called germ pore, the inner layer (intine) develop into a tube called pollen tube.

Role of Pollen Tube: Pollen tube is a source or vehicle to take the male gametes to ovule because there is a little between male gamete and ovule, so pollen tube helps there to take the male gametes to the ovule. Therefore, the development of pollen tube is absolutely necessary, without it the process of fertilisation is not possible.

Development of Male Gametophyte (Pollen): 

    In microsporangia (Pollen Sac) of an anther a large number of diploid microspores mother cells are present. These microspore mother cells divided by meiosis and each from four haploid microspores. Each microspores ultimately divides once by mitosis and produces two cells, one is called generative cell and the other is called tube cell. These two cells surrounded by a thick resistant wall. Two cells and their wall collectively form a pollen grain or immature male gametophyte.

Development of Female Gametophyte (embryo Sac): 

     Ovules contain megasporangia. In megasporangium of each pvule has a megaspore mother cell. This megaspore mother cell grows and divided by meiosis to produce four haploid megespores. In many angiosperms only one of them survive. This megaspore continues to grow and is nucleus divides by mitosis three time. In this way eight haploid nuclei formed, then these nuclei surrounded by partitions. This multicellular structure is called embryo sac, which is the female gametophyte.

        In mature embryo sac there are two groups of three cells at each end. The three cells lying towards micropyle form egg apparatus. One larger cell of this group is called Egg-cell or ovum and the other two are called synergids. The other group of three cells lying towards chalaza is called Antipodal. The other two nuclei called pollar nuclei anther not partitioned into separate cells but these two fused together and form a large central cell called Definite or secondary nucleus. The ovule now consists of the embryo sac. (female gametophyte) and the integuments protective layers of sporophytes tissue around the embryo sac.

Double Fertilization: 
       When pollen grains reach at the stigma of the carpal then development of pollen tube begins. The pollen grains absorb nectar, which initiate the development of tube. The nucleus of pollen grain divided to form two cells one is tube cell and other is generative cell.Tube cell control the growth of pollen tube. The generative cell divides to form two sperms or male gametes. The pollen tube grows towards ovary through style, it carry two sperm cell into the ovule. Now sperm reach the embryo sac. One sperm cell cell fertilizes the egg to form zygote, it is diploid and develops to form embryo. The other sperm fuses with the diploid secondary nucleus (definitive nucleus) to form tiploid endosperm nucleus. It develops to form endosperm, which stores food for the development of embryo, this union of two sperm cell with different cell of the embryo sac is called double fertilization.
      After double fertilization ovule develops into seed and ovary develops into fruit. The seeds are present inside the fruit.

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Reproduction In Plants

(a) Asexual Reproduction: The formation of new individual from single parent without production of gametes is called asexual reproduction in plants the natural methods of reproduction are by spores, vegetables propagation and by Apomixis.

1. By Spores or Sporulation: Spores are asexual haploid cells formed by meiosis in plants the process of spores formation is called sporulation. In plants spores are formed during alternation of generation. In this process two generations saprophytes and gametophytes alternate with each other saprophytes forms the spores. Spores are unicellular cells they detach from parent plant during favourable condition. Spores formation occurs in bacteria, protozoan, algae, fungi, mosses and fern and in all plants.
2. Vegetative Propagation: It involves the separation of a part of the parent plant, which then develops into new plants. Any part of plant body like root, stem, leaf and bud breaks into pieces and each piece develops into new plant. In higher plants some specialised structure are formed for vegetative propagation. e.g. potato is a modified stem which is used for vegetative propagation. If potato is cut into pieces having eyes and burred into soil, each piece of potato will develop into a complete potato plant. In some plants, organs of vegetative propagation also act as parenting organs during unfavourable condition.
3. Apomixis: Apomixis is a process of asexual reproduction in which seeds are formed without fertilisation. In apomixis any cell of the ovule may develop into embryo and ovule changes into seeds. In ovule, egg, any cell of the nucleus, any antipodal cell or any other cell develops into embryo. Some plants only reproduce by apomixis. These are called obligate apomicty plants. Some plants reproduce both sexually and apologetically. They are called facilitative apomictic plants. e.g. apomixis occur in many plants like dandelion.
4. By Cutting: Many plants reproduce asexually by cutting. The plant fragments are called cutting. Cutting of shoots of stem are used. These cuttings are buried into moist soil. The cutting develops into new plant. Adventitious roots develop into two ways, if cutting has no node, the callus is formed at the cut end, which later forms adventitious roots. If cutting has node, then roots develop and callus is not formed. In bryophyllum a single leaf can be used for propagation. If potato is cut into many pieces, each with an eye, will develop into complete plant.

(b) Artificial method of Asexual Reproduction: 

1. Cloning: The production of duplicate copies of genetic material. Cells or complete organism is called cloning. The duplicate copies are called clones. In this process a piece of tissue or a single parenchyma cell is taken and is kept in the test tube containing nutrients and hormones. The cultured cells are divided and form undifferentiated callus. If there is balance of hormone, the callus forms shoots and roots with fully differentiated cells. Now this small plant is transferred to soil for further growth. A single plant can be cloned into thousand of copies by subdividing calluses as they grow. This method is used for the propagation of many plants like orchids and pines.
2. Genetic Engineering: Genetic engineering is also used in tissue culture in this case foreign genes are introduced into the genotype of other plants. Genes one plant are taken and are introduced into the tissue or into single cell of other plants. Now the piece of tissue, or cell is grown in the test tube. This gene works in this plant in the same way as they worked in original plant. In this way a plant is formed which contains two types of genes, their own gene and gene of other plant. e.g. The researches has transferred a gene for bean protein into cultured cells from a sun flower plant.
3. Portoplast Fusion: This technique is also used into tissue culture. By the use of this technique new variety of plants are developed. Protoplasts are plant cells whose cell will is removed. This protoplast may be subjected to mutation. Then these protoplasts can be cloned. In this way agricultural value of the plant is improved. It is also possible in some cases to fuse two protoplasts from different plant species. Now two protoplasts combine to form a single cell which will be developed by tissue culture and from a hybrid plant. This hybrid plant has the characteristics of two types of plants. e.g. A hybrid plant has been formed from potato and black night shade. The nightshade is resistant to herbicide, the hybrids are also resistant and they are not killed by herbicides.

(C) Sexual Reproduction: It is a kind of reproduction in which male and female gametes fuse to form zygote and it develops to form a new plant. Fusion of male and female gametes called fertilisation.

Types of Sexual Reproduction: There are different types of sexual reproduction.

1. Isogamy: The gametes, which are similar in shape, size and structures are called isogametes. The isogametes fuse to form zygote. This is called Isogamy.
2. Oogamy: In this case fusing gametes are dissimilar, both structurally and functionally. One gamete is similar and motile, it is called male gamete or sperm, the other gamete is larger and non-motile and contains food, it is called female gamete or egg. The fusion of egg and sperm to form zygote is called oogamy.
3. Hetero gamy: It occurs in bryophytes and is similar to oogamy. The male gamete is similar and motile while female gamete is larger, non-motile and contains food.

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Plants Hormones - Biology

Plants produce different kinds of chemical substances, which increase the growth and development these chemicals are called plant hormone.

    They effect the gene expression, activities or inhibit enzymes and changes the properties of membrane. These are in very less concentration.

     There are five kinds of plants hormones.

Auxins: Auxin is class of chemicals, which are both natural and synthetic. The most important natural auxin in Acetic Acid (l.A.A), which is found in higher plants. It is synthesised at tips of stem and roots (apical meristem), young leaves and in young embryo within seed. The synthetic aux ins are in dole butyric and naphthalene acetic acid.

Cell Division and Cell Enlargement: The auxin stimulate cell division and cell enlargement, increase the plant in length. It also initiate cell division in the  cambium as a result more xylem and phloem are found, which increase the trans location and thickness of plants.

Initiation of roots: Auxin initiates the development of adventitious roots when applied at the cut base of stem.

Abscission: In mature leaves and fruits less amount of auxin is present, so a abscission layer is formed at the base of petiol and stalk of fruit, this layer consists of thin walled cells.

Growth of Fruit: Auxin produces in young embryo promotes the growth of fruit.

Parthenogenesis: Auxin helps in producing parthenocarpy as seedless fruits, these fruits are formed without fertilisation. 

Apical Dominance: Growth of apical bud inhibits growth of lateral buds below the stem. This is called apical Dominance. So auxin inhibits the growth of lateral buds. If apical bud is cut then lateral buds starts to increase in size.

Weedieide: Auxin's also acts as weeds killer, they kill the broad leaves and seeds. 2-4 dichlarophenoxy acetic acid is to kill weeds in cereal crops.

Gibberellins: Gibberellins are plant hormones that increase cell division and cell enlargement Gibberellins was is covered in fungus gibberella fujikuroi fungus. This fungus cause bakanae disease in rice seeding. 
     The infected seeding elongated and falls. T-Vabuta and T-Hayashi. Isolated a chemical from the fungus and was as gibberellins. Now there are more then seven types of gibberellins.
       They are produced in roots, stem and leaves.
Role of Gibberellins: 
They promote cell division and cell elongation.
They prevent genital and physiological dwarfism.
They promote leaves and fruit growth.
They break bud and seed dormancy.
In some plants they delay senescence in leaves.
They also help to transport food from endosperm to developing embryo.

Cytokinins: These are groups of both natural and synthetic substances, which act as plant hormone. First they were obtaining from coconut milk, now other sources are herring sperm DNA and yeast extract is natural cytokinins which is obtaining from immature corn grains.

Role of Cytokinins: 
They promote rapid cell division in the presence of auxin.
They promote lateral root growth and initiated primary root growth.
They break seed dormancy.
They promote fruit develop.
They promote opening of stomata.

Abscisic acid: Abscisic acid is growth inhibitor and are produced by plant during adverse condition. e.g. Drought Condition.

1. It causes dormancy in buds and seeds.
2. It causes stomata to close.
3. They inhibit stem and root growth waste logging.
4. It promotes leaves senescence.
5. It promotes abscission.

Ethene: It is gas which act as plant hormone. It has many functions.

1. It promotes ripening of fruits.
2. It inhibits stem and roots growth.
3. It breaks dormancy of buds and seeds.
4. It promotes flowering in pineapple.
5. It contributes to leaf abscission.

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Rupert of Hentzall - Character of The Novel ( The Prisoner of Zenda )

Rupert of Hentzall

Introduction: 

   Rupert of Henzall is an important character of the novel. He is one of the six hirelings of the Duke-Michael. He is the most ferocious, reckless and dangerous of them all. He is a rider and an expert swordsman.

Physical Appearance: 

    Rupert is a young man of about twenty five years old. He is very handsome person.

A Very Talkative Fellow: 

     Rupert is a man of very sharp tongue. He knows well how to hurt the feelings of others by his talk. He humiliates lady Mauban severely while talking about woman. When Russendyll challenges him to fight in the forest, he points to a peasant girl and refuses of fight in her presence. In this way the teases Rassendyll. Again, when the Duke Michael finds him alone in Mauban's room and asks him the reason, he promptly replies that he is apologizing to the lady for his long absence. And when Madam De Mauban shoots at him, he replies that he cannot fire at a lady when he has Kissed. 
A Bad Character Fellow: 
      Rupert is a treacherous person. He disrespects his mother by bringing a mistress into her house. He is a flirt and has deceived many woman. He is rough through and through and deceives even his master. He is so vulgar that he always talks nonsense. He knows that Michael wants to become a king and to marry Fla via. But he is also ready to get Michael Killed for his own purposes. Thus he meets Rassendyll in a street of Zenda and suggests that they should kill the king and Michael. He thinks that he can get De Mauban in this way. Thus he opposes his own master. On the other hand he satisfies Michael and tires to kill Rassendyll on different occasions. At last for his own benefit he kills his own master, Michael.
Brave And Daring: 
        Rupert is a dare devil. He is not afraid of any danger and nothing can frighten him. Among the Duke's cut-throats, he is the only great and constant threat to Rassendyll's life. He is an excellent swordsman and saves himself in the encounter with Rassendyll. He is very much reckless and quite  careless about the consequences. Once he tries to kill Rassendyll in bright day light and manages to escape unhunt. Having Murdered Michael, he comes to draw bridge with blood stained sword and stands in the middle of the bridge, fearlessly and bravely. Madam Mauban shoots at him but does not respond to the bullet of Mauban because it was below his dignity to shoot at a woman when he had kissed.
Conclusion: 
            From the study of Rupert's character we come to know that he is a stranger mixture of contradictions. He is grateful and graceless at the some time. His manners make him a detestable character and he plays the role of a villain in the novel to Black Michael.

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