Classification of Plant Kingdom

Depending upon the morphology and the modes of reproduction and life cycle the plants are classified as follows:

Cryptogams (Seedless plants)

(i)    Thallophyta : The members lack the differentiation of plant body into true roots, stems and leaves. They do not possess the mechanical (Collenchyma and Sclerenchyma) and conducting (xylem and phloem) tissues.The organs for reproduction i.e. gametangia are simple and unicellular, they do not possess a layer of jacket. The gemetophytic stage (haploid phase) is dominant over to the sporophytic stage (diploid phase) in the life cycle of these members. The thallophytes have been further divided into two main subdivisions on the basis of mode of nutrition i.e.-

(a)   Algae: They contain photosynthetic pigments like chlorophyll, carotene, xanthophill; Due to presence of these pigments, they are green, red, brown or yellow in colour. They manufacture their own food i.e., they are autotrophic.Their plant body may be unicellular (eg. Chlamydomonas, Chlorella), colonial (Volvox), filamentous (Spirogyra, Ulothrix) or a large thallus (eg. Ficus, Laminaria, Saragassum, Ulva). However the thallus is not diffentiated into true roots, stems and leaves.Conducting tissues i.e. xylem and phloem are absent. Mostly aquatic, some are terrestrial.

(b)   Fungi ; They lack photosynthetic pigments, so they are non-green and heterotrophic, i.e. they do not synthesize their own food but they are depend on others.They may be unicellular (eg. Yeast), or filamentous (eg. Mucor, Rhizopus, Penicillium).Cell wall is composed of fungous-cellulose and chitin.The stored form of food material is fat or oil..The mode of nutrition is either Parasitic or Saprophytic.Most of the species are terrestrial but some are aquatic (eg. Saprolegnia).

(ii)   Bryophyta : They are a group of lower plants. Which can be distinguished by the following characters.They are called amphibians of plant kingdom, having small and green plants they occur near moist and shady places. The plant body is a thallus (not differentiated into true root, stem and leaves) fixed to the soil by hair like structures called rhizoids. The thallus is flat and green in liverworths (eg. Riccia, Marchantia, Pellia, Notothylus) and leafy & erect in mosses (eg. funaria sphagnum). They do not bear flowers and lack vascular or mechanical tissues. The sporophyte is attached to the gametophyte and depends upon it for nutrition.

(iii) Pteridophyta : They show following characters: The dominant stage of life cycle is a sporophate, which is differentiated into roots, stems, and leaves. Vascular tissues (oxlem and phloem) are present. The gametophytic and sporophytic stages are independent of each other. The gametophytic stage requires the presence of water for fertilization e.g. Lycopodium, Selaginella. Equisetum, Marseilea, Dryopteris (fern). etc.

Phenerogams or Spermatophyta ( seed bearing plants)

Spermatophyta are a group of higher plants that bear fruits and seeds. Their body is differentiated into true roots, stem, and leaves. The vascular tissues are very well developed. Like Pteridophytes, the sporophytic phase of life cycle is dominant over gametophytic phase. The gametophytic phase of life cycle is completed with the sporophyte. They have been divided into two subdivisions based on the structure of ovule. They are:

(i)    Gymnospermae: The ovules are naked i.e. the ovules are not enclosed within the ovary. After fertilization, they develop into naked seeds. Microspores and Megaspores are produced within the male and female cones respectively. There is single fertilization.Most of the forms are trees eg. Cyeas, Pitus Cedihis Ephedra Gnetum, Ginkgo etc. The ovules are enclosed within the ovary so after fertilization they develop into seeds enclosed within the fruit. Male and Female gametophytes are highly reduced. The flowers are the organs of reproduction (whereas in gymnosperms. It is mostly cones). There is double fertilization, which leads into the formation of diploid zygote and triploid endosperm.

(i)    Angiospermae: Mostl commonly found plants with their seeds enclosed within the fruit belong to this category.

Photosynthesis

Photosynthesis is the single most important physio-biochemical process on which the existence of life on earth depends. It is the ability of green plants to utilise the energy of light to produce carbon containing organic material from stable inorganic matter by photosynthetic process. It is from the carbohydrate produced by photosynthesis that directly or indirectly all of the organic compounds, which compose of living world, are derived. The oxidation of organic compounds releases stored energy to be utilised by organisms to drive essential metabolic processes. Any energy released during oxidation of organic compounds is ultimately derived from light energy intercepted by green plants during photosynthesis.

In simple terms, photosynthesis can be defined as “the formation of carbon containing compounds from carbon dioxide and water by plant cells. Water and oxygen are the byproducts.”

Ruben and Kamen demonstrated by using isotopes of oxygen and carbon that the source of liberated oxygen is water.

Of these components, water is obtained from the soil by roots of the terrestrial plants and by the general surface by hydrophytes. As a source of light, sun light is utilised. The terrestrial plants absorb CO2 from the atmosphere where is present upto 0.03 per cent while hydrophytes obtain it from the water where it is found dissolved up to 0.3 percent or even more. Due to this reason the hydrophytes produce much more photosynthetic products as compared to terrestrial plants. The CO2 is absorbed by the hydrophytes through the general surface while by the terrestrial plants through the leaves.

Chloroplasts

The site of photosynthesis: All the green parts of the plant carry out photosynthesis and the leaves of all plants are ideally developed for this purpose. The process of photosynthesis takes place entirely within the subcellular organelles called the chloroplasts. Chloroplasts of higher plants are lens shaped or ellipsoidal and are found only in the green cells of plants, they are collectively known as plastids. The chloroplasts are most abundant in the elongated cells of the palisade tissue in the leaf but they also occur in the cells of the spongy mesophyll. The chloroplasts contain the green colouring pigment called chlorophyll.

The chlorophyll plays a purely catalytic role in photosynthesis. It is a complex organic molecule and contains magnesium at the centre. Chlorophyll absorbs light by does not absorb green light. Other pigments like carotene and xanthophylls are also associated with the chlorophyll in the green plant cells; their presence in green leaves is usually marked by the greater abundance of the chloroplast.

Mechanism of photosynthesis

The process of photosynthesis can be divided into two sets of separate but interconnected reaction sequences.

Light or Photochemical or Hill reaction

The site of this reaction is grana in the chloroplast and reactants are light, chloroplast and water. Actually the essence of photosynthetic process lies in the use of light energy for splitting water into Hydrogen ions (H+) and (OH-) ions, this process is called photolysis of water. The electrons released during these reactions eventually reduce the chemical NADP (Nicotinamide Adenine Dinucleotide Phosphate) to NADPH2 (reduced NADP) NADP is a coenzyme capable of readily accepting or donating Hydrogen. The remaining OH ions from water are used to generate oxygen. The energy liberated in the transfer of electrons from one component to another of photo systems is used in the synthesis of ATP (Adenosive Triphosphate) from ADP and IP (inorganic phosphate). Thus electron is released by chlorophyll molecules by absorbing photon (light energy). This is known as photosynthetic phosphoylation or phto phosphoylation. Thus the light reaction of photosynthesis results in the production of:

a.     Reduced enzyme NADPH2

b.      The energy rich compound ATP

c.       Liberated oxygen.

Dark Reaction

ATP and NADPH2 are the substances that link the primary process with the secondary process. They are produced in the primary process and are used to drive the dark reactions of fixation and reduction of carbon dioxide. ATP and NADPH2 are described as the assimilatory power. The dark reaction or carbon reduction cycle is a complex metabolic cycle and is popularly known as the calvin cycle. These reactions involve the intake of carbon dioxide by the plant and its reduction to (CH2O) by hydrogen atoms set free by photolysis of water. This reaction utilizes, the high energy of ATP and the reduced coenzyme NADPH2, Calvin and his associates elucidated the path of carbon in photosynthesis. CO2 is built up into a sugar phosphate called ribulose diphosphate (RUDP), which breaks down into two molecules of Phosphoglyceric acid (PGA). PGa is the first stable product formed in photosynthesis. RUDP is regenerated in the Calvin cycle of reaction. Thus carbon dioxide is built up into the organic molecules through a series of cyclic reactions and sugar (glucose) is ultimately synthesized.

The process of photosynthesis is of vital importance in that it replenishes the oxygen in the atmosphere, which is consumed in animal and plant respiration.

Sexual reproduction in Plants

This is very common type of reproduction in the antiospermic plants. In these plants the vegetative branch at some stage (at maturity or vegetative phase) changes to the reproductive phase i.e. flower. The period and time of bearing flower varies from species to species. Flowers may be bisexual or unisexual. Meiosis (reduction division) occurs in the male and female parts of a flower to form male (pollen g rains) and female (ovun) gametes. In order to produce seeds (to reproduce) male and female gametes fuse together to form zygote that divides mitotically and develops into a seed. The male gamete (pollen grains) are motile and reach up to the ovum for fertilization. This process of transference of pollen grains from the anther of a flower to the stigma of the same or of different flower is called pollination.

Pollination

It is of two types.

(1)   Self-pollination: If the pollen grains are transferred to the stigma of the same flower or between two flowers borne by the same parent then it is self-pollination or autogamy.

(2)   Cross-pollination: If the pollen-grains are transferred to the stigma of a different flower borne by a different flower borne by a different plant then it is called cross-pollination or allogamy.

Adaptations for Self-pollination

The following are the adaptations that a plant shows to favour self-pollination:

(1)   Homogamyation becomes obligatory, eg. Oxalis.

Adaptations for Cross-pollination

All unisexual flowers are cross-pollinated. However the bisexual flowers also show the following characteristics to favour cross-pollination.

(1)   Self-sterility: In this the pollen of a flower does not have the fertilizing effect on the same flower. So only cross-pollination is possible, eg. Tea, Potato etc.

(2)   Dichogamy: Here both the pollen grains and the ovary mature at different times. If is of two types:

        (a)   Protandry: When the stamens mature earlier than the ovary, eg. Cotton, Lady’s finger.

        (b)   Protogyny: When the ovary matures earlier than the stamen eg. Fig. Mirabilis.

(3)   Herkogamy: In some flowers there is a physical barrier between the stamens and the stigma so that self-pollination is prevented. Eg. Iris.

(4)   Heterostyly: Some plants bear flowers of two types i.e. one flower with long stamens and a short style and the other flower with short stamens and a long style. This is called as dimorphic heterostyly. Eg. Rose.

Agencies for Cross pollination

In cross pollination pollen grains are transferred from one flower to another flower through the agency of air, water, insects and other animals. So the lowers shown various morphological adaptations to this external agent., some of these are as follows: Anemophily (wind pollinated flowers ), Entomophily(insect pollinated plants), Hydrophily(pollinated by the agency of water ) , Zoophily(animals like bats, birds, squirrels also act as agents to help pollination)

Fertilization

As the pollen grains reach the stigma of the pistil their development starts. The outer wall called exine breaks and the inner walls called intine grows out as pollen tube. The pollen tube enters the ovule through micropylar end. The ovule has an embryo, which consists of three groups of cell. One egg cells and two synergids lie towards the micropylar end, two definitive nuclei in the centre and three antipodal cells opposite to micropyle. Each ovule consists of a stalk called the funicle, the region of the ovule where funicle is attached is called as chalaza. As pollen tube reaches the ovule it discharges the two male gametes. One gamete fuses with the egg cell to form he diploid zygote. The second fuses with the two definitive or central nuclei to form the triploid endosperm. This is called double fertilization, which is characteristic of angiosperm only.

Seed formation

After fertilization, the part of the flower like sepals, and petals are shed followed by the mitotic division of the zygote. Which leads to formation of embryo. A distinct layer of epidermis can be noted on the surface. Cotyledons are formed, new protective coats are formed and embryo remains dormant. This is the seed.

Fruit formation

A fruit is ripened ovary. In some plants like apple and pear. The fruit is developed from other part than ovary. These are called false fruit. The fruit growth depends upon the development of the seeds, which synthesize hormones. Fruits protect the seeds and help in dispersal. The pericarp in fruit develops from ovary wall. The pericarp has three layers epicarp. mesocarp and endocarp.

Seeds

Fertilised ovule having the capacity to germinate is called a seed. Seeds are produced for the commercial production of crops

Classification of seeds

Breeer’s seed	Foundation seed	Certified seed
Seeds produced after hybridization or mutation are called breeder’s seeds When such seeds contain sufficient hereditary characters, they are called Nucleus seeds iii.            Such seeds possess genetic purity and high quality	The second category of seed in terms of genetic purity is called foundation seed. ii.             Such seeds are produced by some organisation such as National Seed Corporation, State Seed Corporation and Tarai Seed Corporation	These are produced from foundation seeds by two methods In the first method seeds are produced by any government organisation and in the second method under production programmes by certified farmers.

Test (Tetrazolium test)

It is used for testing the germinating power of a seed. Seeds are kept in water at night and then dipped for 2 to 4 hours in the solution of 2.3,5 Tetrazolium chloride or bromide. Colour tetrazolium comes in contact with the enzyme present in the embryo and turns the living  cells red. According to Indian Seed Act, 1966 which is effective from 1 October, 1969 seeds have to be certified before their commercial use.

Seed dormancy

It is a chemical condition where the germinating power of an embryo is reduced even in suitable weather conditions. As a result seeds are not properly developed.

Morphology of Plants

The knowledge of external morphology of angiosperms is essential for the study of all branches of botany i.e. Anatomy, Physiology and Systematics in particular. A typical anagiosperm plant has an underground root system and an aerial shoot system. The shoot system consists of branched or unbranched stem bearing leaves. The reproductive shoot is the flower with its differentiated organs. It is essentially concerned with the reproduction in plants. Broadly, external morphology of an angiosperm plant, can be divided into two classes:

• 1. Vegetative morphology: root, stem, and leaf
• 2. Reproductive morphology: inflorescence flower and fruit.

Vegetative morphology

Root

When the primary root, which is a direct prolongation of the radicle, remains distinct through out of life of the plant and gives off lateral branches it is termed as the tap root system et. in mustard. In many plant other than original root system i.e. from radicle it is known as adventitious root system eg. onion, grasses etc. They along with their usual functions may also be suitably modified to carry out several other functions.

(a)   Modifications of Taproot: In many plants the taproot becomes swollen and assumes various forms due to the storage of food.

 (b) Modifications of Adventitious root: Adventitious root may be modified to carry on the storage of food, mechanical support, and other vital functions,

Stem

The stem is the ascending aerial portion of a plant and develop from the plumule. It is differentiated into nodes and internodes and bears leaves, branches and flowers. Leaves and branches develop from the nodes. In contrast to the root, they possess, buds which may be situated in the axil of the leaf or terminally. A bud is a young undeveloped condensed shoot consisting of a short stem and a number of tender leaves arching over its growing apex. The habit to the plant is displayed by its stem. Herbs are small plants with soft stems. Medium sized plants with hard and woody stems that branch profusely to attain a bushy appearance are called Shrubs. Trees are plants having stout and long trunks with professed branching according to their life span. The plants may be annuals, biennials, and perennials. Plants, which complete their life cycle in one season, only are termed annuals, eg. Rice, sunflower etc. Biennials complete their life cycle in two seasons eg. Radish, cabbage. Plants that usually survive for a number of years and produce flowers and fruits during specific period each year are termed perennials eg. Mango, bamboos.

Modification of Stem: Besides their usual function, stems often get modified to perform other functions such as perennation and vegetative propagation as the result; their forms are greatly changed. There are three types of modified stems:

1.    Underground modifications of stems: They appear like roots but are distinguishable from the roots in having scale leaves at the nodes and buds, such stems also act as a means of vegetative propagation.

2.    Sub-aerial modification of stem: In some cases aerial branches and adventitious roots develop at the nodes, which may behave as an independent plant when detached.

3.    Aerial modification of stem: They greatly vary in form but can be distinguished easily by their position in the axil of a leaf or at the apex.

Branching of the Stem: In most of the cases new branches arise from the sides of the main stem that is called lateral branching which is of two types:

(i)    Racemose (or indefinite or monopodial type of branching). The main stem continues to grow indefinitely by its terminal bud. The mode of branching is termed acropetal eg. Casuarina, Ashok tree.

(ii)   Cymose: In this case the terminal bud of a branch ceases to grow but lateral branches, varying in number soon develop and grow vigorously from below. The mode of branching is basipetal, eg. Datura, Croton etc.

Leaf

The left is a flattened lateral outgrowth of the stem and bears a bud in its axil. A typical angiosperm leaf consists of three parts:

(1)

Leaf base

(2) Petiole

(3)

Lamina

In many plants the leaf base is swollen and is termed pulvinus. The arrangement of veins in the lamina is termed as ventation. It is of two types:

(1)   Reticulate: When the veins are forming a network, it is characteristic feature of the dicots.

(2)   Parallel: When the veins are parallel and do not form a network. It is characteristic of monocots.

Simple and Compound leaf: A leaf is said to be simple when its lamina is entire or incised but the incisions do not touch the mid rib. When the incision of the lamina goes down to the mid-rib the leaf becomes compound and it has a number of leaf segments, these leaf segments are known as leaflets. A leaflet is like a simple leaf but it lacks a bud in its axil. A compound leaf is said to be pinnate when the leaflets are lateral to the mid-rib, it may be unipinnate, eg. Rose: Bipinnate, eg. gold mohur (Delonix) and Tripinnate, eg. Moringa. In palmately compound leaves the petiole bears a number of leaflets which resemble a palm. Depending upon the number of leaflets, it may be Unifoliate, eg. Lemon, Bifoliate, Trifoliate, eg. Wood apple; Quadrifoliate eg. Marsilea and Multifoliate eg Bombax, Cleome.

Modification of leaves: Some of the important modifications of leaves are:

(1)   Tendril: Modified for the purpose of climbing, eg. Pea.

(2)   Spine: Modified for the purpose of defence, eg. Opuntia.

(3)   Scale leaves: eg. In Onion.

(4)   Pitcher: In some of the insectivorous plants, eg. Nepenthes, the lamina assumes the form of a pitcher with a lid to trap the insects, the inner walls of the pitchers posses a number of digestive glands which secrete a fluid.

(5)   Phyllode: When the petiole becomes leaflike, it is termed as phyllode, eg. Australian Acacia.

Reproduction Morphology

Flowers, constitute the reproductive organs. A flower is a specialized shoot essentially meant for sexual reproduction and has evolved as a result of progressive speculation of reproductive structures.

Inflorescence

It is a reproductive shoot bearing a number of flowers in terminal or axillary position. It is of three types recemose, cymose and special type. In racemose, the main axis is unlimited in growth, whereas in cymose, the growth of main axis is limited. It is of following types:

(1)   Raceme: The main axis of inflorescence bears stalked flowers, eg. Mustard, Radish etc.

(2)   Spike: This is like raceme but the flowers are sessile, eg. Adhatoda.

(3)   Catkins: The main axis of inflorescence, which is a long and pendulous bears unisexual flowers, eg. Mulberry.

(4)   Spadix: The main axis inflorescence is fleshy enclosed by one or several large and brightly coloured bracts called the spathes, eg. Banana.

(5)   Corymb: The main axis is short and bears stalked flowers in such a manner that they are placed almost at the same level, eg. Lantana, Cherry.

(6)   Umbel: It has very shortened and suppressed axis, flowers have stalks of equal length, and it is umbrella like in appearance eg. Coriander, Carrot.

(7)   Head of Capitulum: The main axis is flattened, more or less convex structure. On the receptacle, florets are arranged in a centripetal order, eg. Sunflower.

Special types of inflorescence

(1)   Hypanthodium: The main axis forms a cup shaped receptacle with a small opening at the top. Flowers are arranged within the cup eg. Ficus.

(2)   Cyathium: Here, one central flowers (represented by a single pistil) is surrounded by a large number of male flowers (each represented by single statements) the whole structure is enclosed in cup like structure, eg. Euphoribia, Pedialanthus.

(3)   Verticillaster: Flowers are sessile and appear in a flase whorl or vertically around the stem. Eg. Ocinum (Tulasi).

Flower

The flower is a highly specialized condensed structure. The axis of the flower is known as thalamus. A typical flower shows four sets of members arranged in successive whorls. They are calyx, corolla, androceium, and gynaecium. Calyx and corolla constitute accessory whorls and Androecium and Gynaecium constitute the essential whorls of the flower. When calyx and corolla are undistin-tuishable, they are known as perianth (common among monocots). In absence of accessory whorls, it is known as achlamydous. When all the four parts of a flower are present, it is termed as complete. In the absence of any one of these, it is termed as incomplete. When both male and female component (androecium and gynoecium respectively) are present in the same flower, it is termed as bisexual or hermaphrodite. Unisexual, flowers it may be staminate (when gynaecium is absent) or pistillate (when androecium is absent). A flower without any functional stamen or pistil, it is known as neuter or sterile. If male and female flowers develop on the same plant. It is called monoecious, otheriwse, it is dioecious. A flower is said to be an actinomorphic when its symmetry remains undisturbed, even after cutting the flower into two halves through the axis where as zygomorphic flowers are those where their symmetry get disturbed after cutting the flower into more than two halves through their main axis. All the flowers, broadly, can be divided into 3 types, depending upon the relative positions of the floral parts on thalamus. I.e.

(1)   Hypogyny: When the other floral part i.e. sepals, petals, stamens are inserted on thalamus below the ovary in the flower, eg. China rose.

(2)   Epigyny: When the other floral parts are inserted above the ovary in the flower, the ovary in this case is said to be inferior, eg. Guava, Cucumber etc.

(3)   Perigyny: When the other floral parts are inserted at the same level at the ovary, eg. Rose, Pea etc.

Fruit

Fruit is a characteristic feature of the flowering plants. It may develop either after fertilization of without fertilization. The fruit, which is produced without fertilization, is called parthenocarpic fruit, eg. Banana. Citrus, Grape etc. Fruits are of two types:

(a)   True fruits: which develop from the ovary.

(b)   False fruits: which develop from any other floral parts except ovary.

Essential nutrients for plant growth

Element	Source		Ionic form
Carbon, Oxygen,	Air	Carbonate (CO3)
Hydrogen,	Water	H & OH
Nitrogen	Soil	Ammonium (NH4), Nitrates (NO3)
Phosphorus	Soil	K+
Calcium	Soil	Ca++
Magnesium	Soil	Mg++
Sulphur	Soil	So3-, SO4-
Iron	Soil	Fe++, Fe+++
Manganese	Soil	Mn++, Mn +++
Boron	Soil	BO3
Zinc	Soil	Zn++
Chlonne	Soil	C1-

Agar-agar	A polysaccharide, obtained from cell-walls of red-algae (Gelidium, Gracillaria) which remains semisolid at room temperature, used as an emulsifying agent in pharmaceuticals, and also to solidify the synthetic media for artificial cultural work.
Allopolyploid	An organism containing more than two enomes derived from two or more different species.
Autotrophic	organisms, which can manufacture their food on their own.
Bacteriophage	A virus, which multiplies in a bacterial cell and lyses the cell in which it multiplied.
Biome	A group of similar types of communities, unified in the types of organisms they contain and their responses to environment.
Biosphere	The envelope containing all living things on earth.
Cerebellum	The fourth part of the brain in vertebrates, which governs the muscular coordination.
Ecosystem	A self-sustaining energy driven and interacting system of living organisms and their non-living environment.
Ecotone	Transitional zone between two vegetational types or regions.
Eugenics	The science, which deals with the improvement of the inborn or hereditary qualities in a series of generation of the human race.
Euthenics	The science dealing with the betterment of living conditions.
Facultative parasite	An organism, which is basically a saprophyte but can live as a parasite, if it gets a suitable host.
Fungicide	Chemical used to kill or inhibit the growth of fungal mycalium.
Filaria	It is caused by the bite of a male mosquito. It generally occurs in Bengal, Bihar, Orissa and practically all places with poor drainage.
American yellow fever	It is caused by the bite of Culex mosquito.
Diabetes	It is due to inability of pancreas to secrete sufficient insulin to make use of sugar in the food.
Scarlet fever	The infection spreads by breath and secretions of the nose, mouth and throat. The onset is sudden with shivering, vomiting and sore throat. The cheeks become flushed and there is marked pale circle round the mouth. The temperature is high.
Mumps	The swelling of the salivary glands in front of the ears, which makes the face look dull. Fluid diet and rest in bed is the best cure.
Meningitis	It means inflammation proximal principles in the right proportion required for the maintenance of health. We cannot get all these in a single article of food. To get these in right proportion, we have to mix certain articles in our diet and thus we require a ‘mixed diet’ or a balanced diet.
Red Blood Corpuscles (RBC)	Red corpuscles are circular, boconvex discs. They can be seen under a microscope. They are pale yellow in colour. They contain an iron compound called haemoglobin. They give red colour to the blood. They supply oxygen to the body. Ratio being 500/1 for RBC and WBC respectively.
White Blood Corpuscles (WBC)	WBC is very few. They have no definite shape. Their movements are like those of an amoeba. They are also called leucocytes. They are soldiers of the body and protect it
Sporadic	A disease, which occurs here and there in an area with apparently no connection with its origin.
Pandemic	A disease, which affects two or more countries or even continents, such as the flu of 1956.
Tuberculosis	It is caused by tubercle bacillus. Weak chest, dusty occupation, over-work, chronic worry, starvation, early marriage, malaria, influenza, all these increase susceptibility to T.B. by lowering general vitality.
Small pox	It is a viral disease. The onset is sudden, with headache and backache followed by vomiting fever and running of the nose. Eruption on the skin, small red pimples becomes pocks on the third day. Scabs fall on the 14th day leaving behind pits or scars on the skin.
Cholera	It is caused by Vibrio Cholerae characterized by passing copious of the meningi. It generally attacks children and the symptoms are headache, vomiting and high fever, there is pain in the back as well as in the legs, and there is stiffness of the neck. Sulpha drugs are best treatment.
Cancer	It is caused due to irregular growth of some cells in the body. These cells interfere with the normal activities of other healthy cells. Irregular growth of cells is caused by exposure to abnormal heat, radiation and chemical fumes. At present, there is no remedy for this disease except exposing the cancerous cells to radioactive rays (cobalt-60). Cancer can affect any part of the body.
Inoculation	Inoculation means the introduction of germs of the same disease below the skin so as to produce the disease in a mild form and thus gain immunity from a severe attack of the same disease. Inoculation is done as a preventive measure against plague, cholera, typhoid etc.
Plasma	Plasma is a pale yellow liquid and contains 90% water, the corpuscles float in it.
Clotting of blood	The plasma consists of fibrinogen and serum on exposure, fibrinogen is converted into fibrin, which being insoluble in serum forms a network, in meshes of which blood corpuscles get entangled, and clot is formed. In this way bleeding is stopped automatically after sometime.
Blood transfusion	It is the introduction of the blood of similar composition and nature into a person suffering from bloodlessness. One can donate 250 c.c. Or 8% of the total blood at a time. It was first introduced by Landsteiner.
Audiometer	An instrument to measure difference in hearing.
Clinical Thermometer	A thermometer for measuring the temperature of human body.
Sphygmomanometer	An apparatus for measuring blood pressure.
Stethoscope	A medical instrument for hearing and analyzing the sound of heart and lungs.
Inversion	Reversal of the order of a block of genes in a given chromosome.
Isomorphic	a file-cycle in which gametophyte and sporophyte are morphologically similar.
Karyolype	Characteristic size and shape of chromosomes of an organism at mitotic metaphase.
Keratin	A structural protein, which forms the chemical basis of horn hair, nails, feathers and epidermal scales.
Ontogeny	The developmental stages in the life of an individual from fertilized egg to the adult stage.
Pepsin	An enzyme produced in the stomach of vertebrates, which changes proteins to peptones.
Prostrate glands	A gland connected with the male reproductive system and producing a secretion that stimulates the activity of sperm cells.
Petrification	A type of plant fossil in which the original cellular tissues are retained and impregnated with mineral compounds.
Placenta	The region within the ovary where one or more ovules are attached.
Quantosome	A photosynthetic unit comprising 200-300 chlorophyll molecules, located on photosynthetic lamella in chloroplasts, and capable of capturing one quantum of light at a time.
Recessive gene	That member of a pair of genes, when both the member of the pair are present, in subordinate or suppressed by the other, dominant gene.
Recon	The smallest length of DNA that is capable of recombination, which sometimes can represent only one nucleotide.
Reflex Arc	A chain of nerve cells numbering three a receptor neuron on the surface which receives a stimulus and passes the effect as an impulse to an adjustor neurons
Reflex action	this in turn passes it on to an effector cell that performs the appropriate activity.
Sebaceous glands	The oil glands connected with the hair of mammals.
Sinus venosus	Chamber of vertebrate heart between veins and auricle, it is absent in birds and mammals.
Systole	Heartbeat in which its muscles contract to pump blood into the arteries or contraction of contractile vacuole in protozoa.
Umbilical cord	Stalk arising from ventral side of embryo of mammal and joining the placenta, contains mesoderm blood vessels and parts of yolk sac and allantois, it breaks at birth.
Uterus	Womb, enlarged end portion of oviduct in female mammals in which embryo develops, it may be paired or single.
Vestigial organ	An organ, which was well developed in form and function but in due course of evolution, has reduced very much so that only non-functional trace is left, but it may be functional in embryonic development through its former adult function has disappeared.
Wandering Cell	A leukocyte that moves about in the tissue of the body.
Yolk	Stored food in the form of protein and fats in eggs.
Xeromorphic	Team referring to anatomical modifications of the leaf of Xerophytes.
Zymogen	A substance that is developed in a gland cell and which may be changed into an enzyme.
Etiology	Etiology is the study of causation of disease. It may be intrinsic (within the body) or extrinsic (outside the body).
Pathology	Pathology deals with the study of diseases and their causes.
Homeostasis	The mechanism by which the body is kept in equilibrium is known as Homeostasis.
Predisposing Causes	are those that make the person susceptible to the disease and are also known as remote, distant or preparatory causes.
Pathogenesis	The mechanism by which the causes produce disease.
Incubation period	is the time that elapses between the action of a cause and manifestation of disease.
Prognosis	is the estimation of probable severity and outcome of disease.
Morbidity	is the percentage of deaths among population affected by a disease.
Autopsy	is seeing with ones own eyes. Also known as necropsy.
Biopsy	is examination of tissues received from living body with loss of consciousness
Edema	Abnormal accumulation of fluid in the intercellular spaces and body cavities.
Burn	The tissue changes that occur on excessive absorption of heat by skin are known as burns. Burns can be classified as (a)          First degree of burn - Only epidermis alone is affected.   (b) Second degree of burn- Necrosis of epidermal tissue, vesicles formation. (c)             Third degree burn- Epidermis and dermis are damaged; blood vessels, hair follicles, sweat & sebaceous glands are destroyed.(d)Fourth degree burn- Subcutaneous facial and deeper tissues are also affected.
The Electrocardiogram	The changes in electrical potential associated with the initiation and spread of cardiac impulse can be recorded from the surface of the body by an appropriate instrument. The instrument is usually an extremely sensitive galvanometer known as the electrocardiograph. The graphic recordings made on a moving strip of paper are known as electrocardiogram