Kingdom-Plantae

Kingdom-Plantae includes eukaryotic, autotrophic or photosynthetic and non-motile organisms. They have well defined cellulosic cell wall. Plastids are present. Plant kingdom include five major plant groups i.e., Algae, Bryophyta, Pteridophyta, Gymnosperms and Angiosperms as proposed by R.H. Whittaker.

Characteristics Feature Of Kingdom-Plantae

  1. This kingdom includes plants which are multicellular eukaryotes.
  2. All plants contain plastids. Plastids are double membrane organelle that posses photosynthetic pigments. They are called chloroplasts.
  3. They are usually autotrophic. Chloroplast contains a green colour pigment called chlorophyll and prepares its own food by the process of photosynthesis.
  4. The cell walls possess mainly cellulose.
  5. The plant body may be thalloid or differentiated into root, stem and leaves.
  6. They may be non-vascular or vascular.
  7. They have two stages in their life cycle- a haploid and a diploid. Haploid stage is sexually reproducing gametophytic generation and diploid stage is asexually reproducing sporophytic generation. The two generation alternate. This is called alternation of generation.

Classification Of Kingdom-plantae

Classification of Kingdom-plantae has many levels.
  1. Differentiation of plant body parts.
  2. Presence of Vascular System
  3. Presence of seed
  4. Covering of seed
  5. Number of Cotyledons.

Kingdom-plantae

Contents

1. Algae
2. Bryophyta
3. Pteridophyta
4. Gymnosperm
5. Angiosperm
6. Plant Life Cycles and Alternation of Generations

Kingdom Protista

Prtotisa is kingdom of unicellular eukaryotes. It is a kingdom of exclusion. Organisms that are not clearly bacteria, fungi, plants or animals are grouped into this large and diverse kingdom. The organisms in kingdom protista have some common features of other kingdoms. Some are autotrophic and are producers in marine and aquatic ecosystems like plant. Some are saprophyte and break down dead matter, like fungi. Some eat, move and behave very much like animals. This kingdom forms a connecting link between monera (prokaryotes) and plants, animals and fungi (multicellular eukaryotes).

General Features

  • All members are microscopic, unicellular, eukaryotic organisms.
  • Cell with one or more well developed nucleus.
  • Presence of well developed membrane bound organelles.
  • Mode of nutrition may be parasitic, ingestive, photosynthetic, saprophytic, mixotrophic etc.
  • This group includes photosynthetic phytoplanktons, non-photosynthetic zooplanktons and disease causing parasites.
  • Reproduction occurs by asexual (binary or multiple fission) and sexual reproduction (by syngamy).
  • Two types of life cycles are found in protists: Life cycle showing zygotic meiosis and life cycle showing gametic meiosis.

Classification of Protista

There are four division or phylum in protista:
1. Dinoflagellates
2. Chrysophytes
3. Euglenoids
4. Slime molds
5. Protozoans

Dinoflagellates

  • These organisms are mostly marine and photosynthetic. They appear yellow, green, brown, blue or red depending on the main pigments present in their cells.
  • The cell wall is divided in to plates, which is made up of cellulose. Due to this stiff cellulose plates on the outer surface they are called armoured algae.
  • Most of them have two flagella, one lies longitudinally and the other transversely in a furrow between the wall plates. Due to this dinoflagellate shows a special type of whorling motion. Therefore they are called as "whorling whips".
  • Chromosome of them doesn't contain histone protein, due to this they are known as mesokaryotes.
  • Dinoflagellates like Noctilluca, Gonyaulax show "bioluminescence" due to presence of photogenic granules in cytoplasm. These dinoflagellates are known as night light. Due to presence of bioluminescence dinoflagellates are also known as "Fire algae".
  • Noctilluca is knwon as Sea ghost, because it glows in night.
  • Red tides: Red dinoflagellates (Example: Gonyaulax) undergo such rapid multiplication that they make the sea appear red. This red coloured water bloom is known as Red tides. They secrete toxins, which are known as "saxitoxin". Saxitoxin (STX) is a neurotoxin that can kill other marine animals such as fishes. It is accumulated in these organisms. Human aquire these toxins through food chain. Due to it they cause paralysis in human.

Red tide

Chrysophyta

  • This group include diatoms and golden algae (desmids).
  • They are found in fresh water as well as in marine environment.
  • They are microscopic and float passively in water currents (plankton).
  • Most of them are photosynthetic and are chief producers in the oceans.
  • In diatoms the cell walls form two thin overlapping shells, which fit together as in a soap box.
  • The cell wall of diatoms is made up of cellulose in which silica particles are embedded in at many places. This silicated cell wall is called "shell" or "frustule". This is hard. This cell wall does not get destroyed after their death. Thus diatoms have left behind large amount of cell wall deposits in their habitat. This accumulation is referred as diatomaceous earth or keiselgura.
  • Being gritty diatomaceous earth is used in polishing, filtration of oils and syrups. They are also used as heat insulator and as sound proofing substance.

Euglenophyta or Euglenoids

  • This division includes Euglena like flagellates. Majority of them are fresh water organisms found in stagnant water.
  • They are unicellular, cell wall absent. Instead of a cell wall, they have a protein rich layer called pellicle which makes their body flexible.
  • They have two flagella, a short and a long one. At the base of the flagellum there is a light-sensitive swelling, and to one side of it a red pigment spot. These structures guide the organism towards light when it is swimming.
  • Euglena swim in water with the help of flagellum. If the water dries up, Euglena stops using its flagellum and wriggles around like a little worm. This movement is knwon as metaboly or euglenoid movements.
  • Example: Euglena, Peranema etc.
  • Euglenais also known as connecting link between plant and animal kingdom. Because it has some features of both kingdoms. They are photosynthetic in presence of sunlight (Plant like feature) but in absence of light or in dim light they behave heterotophs by predating on other smaller organisms (Animal like feature).

Slime Moulds

Slime moulds are saprophytic protists. Slime moulds consist of spreading slimy mass of protoplasm. The body moves along decaying twigs and leaves engulfling organic material. They are unicellular organism which lack cell walls and have the plasma membrane as their outer covering. They are also knwon as false fungi. Their are two types of slime moulds are present:

  • Acellular slime moulds: Their body is made up of wall less multinucleated protoplasmic mass. This type of body is known as plasmodium. (Plamodium = wall less coenocytes). They are diploid.
  • Cellular slime moulds: Group of amoeba like cells is known as cellular slime moulds. They are known as myxamoeba or pseudoplasmodium. They are haploid.

Under suitable conditions, they form an aggregation called plasmodium which may grow and spread over several feet. During unfavorable conditions, the plasmodium differentiates and forms fruiting bodies bearing spores at their tips. The spores possess true walls. They are extremely resistant and survive for many years, even under adverse conditions. The spore are dispersed by air currents.

Protozoa

  • All protozoans are heterotrophs and live as predators or parasites.
  • They are believed to be primitive relatives of animals. (Proto = Primitive + Zoan = Animals).
  • There are four major groups of protozoans:
  • (A) Amoeboid protozoan: They are known as sarcodines. These organisms live in fresh water, sea water or moist soil. They move and capture their prey by putting out pseudopodia (false feet) as in Amoeba. Marine forms have silica shells on their surface. Some of them such as Entamoeba are parasites. Example: Entamoeba histolyticaAmoebiasis. Entamoeba gingivalisPyorrhoes.
  • (B) Flagellated protozoans: They are known as zooflagellates. The members of this group are either free living or parasitic. They have one to several flagella for locomotion. Example: Trypanosoma (It produces sleeping sickness disease).
  • (C) Ciliated protozoans: They are known as ciliates. These are aquatic, actively moving organisms because of the presence of thousand of cilia. They have a cavity (gullet) that opens to the outside of the cell surface. The coordinated movement of rows of cilia causes the water current with food to be steered into the gullet. Example: Paramoecium.
  • (D) Sporozoans: This includes diverse organisms that have an infectious spore like stage in their life cycle. Locomotory organs (cilia, flagella, pseudopodia etc.) are absent. Plasmodium (malarial parasite)

Eubacteria

Monera contain two groups of bacteria. One is archaebacteria and other is Eubacteria. Evolutionary Eubacteria are more developed. Eubacteria are more advanced than archaebacteria and can live everywhere on Earth, except in the most extreme archaebacterial environments. All bacterial illnesses are caused by eubacteria.

Structure Of Eubacteria

Bacterial cell has a chemically complex cell envelope. The cell envelope consists of a tightly bound three layered structure. Outermost glycocalyx, cell wall and  cell membrane. Although each layer of the envelope performs distinct function they act together as a single protective unit.

Glycocalyx

Loose and thin layer is slime layer and thick and tough layer is capsule. When bacteria are surrounded by capsule, called as capsulated bacteria. Formation of capsule is done by cell membrane. Capsulated bacteria are mostly pathogenic. Capsule is made up of polysaccharides and polypeptides while slime layer is made up of only polysaccharides. Glycocalyx protects the bacteria from WBC and also helps in colony formation.

Cell Wall

Bacterial cell wall is made up of mainly peptidoglycan or murein which is a type of muco-peptide.

Difference

Cell Membrane

Bacterial cell membrane is made up of lipoprotein like the eukaryotic membrane.

Types of Eubacteria

Cyanobacteria

  • Cyanobacteria have chlorophyll (similar to green plants) and are photosynthetic autotrophs.
  • Cyanobacteria were the first organisms that produced O2 on our earth and also known as BGA.
  • The cyanobacteria are unicellular (Spirullina), colonial (Anabaena) or filamentous (Oscillatoria).
  • They may be freshwater or marine or terrestrial algae.
  • The cytoplasm of prokaryotes lacks membrane bound cell organelles but exceptionally in BGA two membrarne bound structure are present: Gas vacuole and thylakoids. Gas vacuole provides the buoyancy to the BGA in water. Thylakoids contain photosynthetic pigments.
  • The colonies are generally surrounded by gelatinous sheath.
  • They often form blooms in polluted water bodies. Excessive growth of BGA in water, that pollute the water is knwon as water bloom.
  • Some of BGA can perform Nitrogen fixation. They converts atmospheric nitrogen in to nitrogenous compound like amino acids, nitrates.
  • BGA fix nitrogen in two forms: Symbiotic form and Free living form.
  • Some of these organisms can fix atmospheric nitrogen in specialised cell called heterocysts. Example: Nostoc and Anabaena.
  • Heterocysts is thick walled, non green cell.
  • Cyanobacteria contain special type of gene nif-gene (Nitrogenase inducing factor). It stimulates the production of nitrogenase enzyme. Nitrogenase is necessory for nitrogen fixation.

Cyanobacteria

Chemosynthetic Autotrophic

  • These are nonphotosynthetic autotrophs. They use chemical energy instead of light energy for food synthesis. Chemical energy is obtained from oxidation of chemical compounds.
  • Bacteria oxidise various inorganic substances such as nitrates, nitrites and ammonia and use the released energy for their ATP production.
  • They play a great role in recycling nutrients like nitrogen, phosphorous, iron and sulphur.

Heterotrophic Bacteria

  • These are the most abundant in nature.
  • The majority are important decomposers.
  • Many of them have a significant impact on human affairs. They are helpful in making curd from milk, production of antibiotics, fixing nitrogen in legume roots, etc.
  • Some are pathogens causing damage to human being, crops, farm animals and pets. Cholera diseases caused by different bacteria.

Photosynthetic Bacteria

  • Some of bacteria use light energy for food synthesis. But this photosynthesis is non oxygenic.
  • Photolysis of water does not take place here, so hydrogen is received from other sources like inorganic sulphur compounds (H2S) or organic compound (Amino acids, Fatty acid etc.)
  • Example: Sulphur producing bacteria.

Mycoplasma

  • Mycoplasma are organisms that completely lack a cell wall.
  • These are the smallest living cells known and can survive without oxygen.
  • Many mycoplasma are pathogenic in animals and plants.

Reproduction In Bacteria

Bacteria reproduce by two methods: Asexual and Genetic Recombination.

Asexual Reproduction

Asexual reproduction takes place by binary fission and by endospore.

Genetic Reproduction

It is similar to sexual reproduction but it is not true sexual reproduction. Because it does not involve fusion of male and female gametes to produce a diploid zygote. Genetic recombination involves transfer of some genes from a bacterium to another bacterium. There are two methods of genetic recombination: Transformation and Conjugation.

Archaebacteria

Archaebacteria means "ancient bacteria". They were the only organisms on the planet for millions of years. They are still present with their primitive characters so they are the "Oldest living fossils". They are adapted to life in regions where no other living thing can survive.

Characteristics Of Archaebacteria

  • Mostly they are obligate anaerobes. They cannot tolerate the presence of oxygen.
  • Cell wall of archaebacteria lack peptidoglycan (murein). They have pseudopeptidoglycan. It is different from bacterial peptidoglycan in chemical structure, but resembles in function. Human lysozyme can degrade peptidoglycan but ineffective on pseudopeptidoglycan.
  • Further branched chain ether linked lipid are present in plasma membrane of archaebacteria, due to which these can face extreme of conditions of temperature and pH.

Types Of Archaebacteria

Archaebacteria can classified into three categories on the basis of home environments: Methanogens, Thermoacidophiles and Halophiles.

Methanogens

  • Methane producing bacteria
  • These bacteria convert CO2 of swampy areas into methane.
  • These bacteria convert the organic substance present in cow dung into methane by fermentation. (Gobas gas fermenter) Example: Methanococcus.
  • They are also present in the rumen of cattle, where it digests the cellulose by fermentation and convert it into methane. Example: Rumenococcus

Halophiles

  • Halphiles means Salt loving.
  • They are found in extreme salty areas such as the Great Salt Lake and the Dead Sea. 
  • Halophiles are surrounded by purple membrane in which a pigment, bacteriorhodopsin is found due to this reason membrane absorbs the bright light and directly forms ATP i.e. they cannot prepare food like eubacteria. Instead of it they directly form ATP. Therefore They are non photosynthetic.

Types of Archaebacteria

Thermoacidophiles

  • Thermoacidophiles means heat and acid loving.
  • These archaebacteria are found at those places where temperature is approx 80oC – 100oC and medium is acidic.
  • These are aerobic bacteria, which have the capacity to oxidise sulphur to H2SO4 at high temperature and high acidity.
  • Some of these bacteria are able to reduce sulphur to H2S under anerobic conditions.
  • They are found in hot sulphur springs such as Yellowstone National park.

Kingdom Monera

Monera is kingdom of prokaryotes. Therefore, it is also known as prokaryota. Members of Monera are adapted to all types of habitats, because it includes the most primitive and earliest forms of life. Bacteria are the simplest life forms on earth. They exist everywhere on the planet. Bacteria live in environments no other living thing can tolerate, such as thermal hot springs and supersaturated saline environments. They can live within other living organisms. Bacteria can live at the bottom of the ocean, near deep sea vents, where the water temperature is close to 400oC. Bacteria were probably the earliest life forms on earth.

Characteristics Of Monera

  • Monerans are basically unicellular prokaryotes and contain the most primitive form of life.
  • On the basis of nutrition they are saprotrophic, parasitic, chemoautotrophic, photoautotrophic and symbiotic.
  • On the basis of respiration they may be aerobic or anaerobic.
  • Cell wall is generally present. It contains peptidoglycan and polysaccharides (other than cellulose). Peptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane.
  • Cell membrane is present and made of lipoprotein.
  • Cytoplasm of bacteria or monera lacks membrane bound cell organelles liek mitochondria, lysosome, golgibody, plastids etc.
  • Genetic material is not organised into a nucleus. Instead of nucleus, they have nucleiod. Nucleiod doesn't has nuclear membrane and nucleolus.
  • DNA is naked, i.e. it is not associated with histone proteins. DNA is circular. DNA combined with non histone protein is known as nucleiod. It is equivalent to one chromosome.
  • Besides nuclear DNA, in some bacteria extra-chromosomal DNA are present which is knwon as plasmid.
  • In prokaryotes ribosomes are of 70s type.
  • Reproduction is done by asexual reproduction but in some case gene recombination also take place.

Shape Of Bacteria

Bacteria have variations in their shape. On the basis of their shape bacteria are of following types:

  • Coccus/Cocci :They are spherical shaped.
  • Bacillus/Bacilli : They are rod shaped.
  • Spirillum/Spirilla :These are spiral shaped bacteria.
  • Comma/Vibrio :These are comma shaped bacteria.
  • Bacili are most abudant bacteria.
  • Coccus are smallest and maximum resistant bacteria.

Shape of Bacteria

Note: There are some prefixes also used to show how bacteria group themeselves together. They self-organize into long chains, grape-like clusters, or paris. For pair arrangement we use "diplo-" prefix. For chain arrangement we use "strepto-" prefix. For clusters arrangement we use "staphylo-" prefix. Example: The bacteria that cause the disease strep throat are called Streptococcus. The prefix "strepto-" means chain, and the "coccus" means sphere". It means these bacteria are spherical in shape and grouped in chain like structure.

Some Important Point


  • Anton von leeuwenhoek first saw bacteria.
  • Louis pasteur gave germ theory of diseases.
  • Robert Koch first of call cultured bacteria.
  • The branch biology which deals with study of bacteria is known as bacteriology.
  • There are three types of plasmid:

     

    1. F-factor or fertility factor: It is responsible for transfer of genetic material.
    2. R-factor or resistance factor: It provides resistance against drugs.
    3. Colicinogenic factor: It produces colicines which kill other bacteria.

Classification Of Bacteria

There are two major groups of bacteria:

Taxonomy

Taxis = arrangement, nomos = law. Taxonomy

All living organisms are classified into various groups based on their characteristics according to the principles of identification, nomenclature and classification. The branch of biology which deals with the study of identification, classification and nomenclature is known as taxonomy.

Taxonomy Chart

Classification


The arrangement of organism in taxonomic group according to similarities and dis-similarities is known as classification. The purpose of biological classification is to organise the vast number of known organisms into categories that could be named, remembered and studied. There are two types of classification: Empirical Classification and Rational Classification.

Empirical Classification

In this type, the actual nature or character of plants is not considered. Plants are classified on the basis of their alphabetical order of their name. On the basis of name, plant kingdom can be classified into 26 groups.

Rational Classification

In this classification, plants are classified on the basis of their actual character or nature. There are three principle system of classification- artificial, natural and phylogenetic systems.

Artifical Classification

It is based on one or few external morphological characters of organisms. It is earliest system of classification. Example: Theophrastus classified plants as trees, shrubs and herbs. Aristotle classified animals as enaima and anaima, on the basis of the presence or absence of red coloured blood.

Natural system of classification

It is based on the overall morphological, embryology and anatomical characteristics, which indicate natural relationships among organisms. Example: George Bentham and J. Hooker gave most important natural system of classification of angiosperms, published in ‘Genera Plantarum‘.

Phylogenetic system of classification

This system of classification is based on the evolutionary descent of a group of organisms. In this system, organisms belonging to the same taxa are believed to have common ancestry and may be represented in a family tree called cladogram.

Taxonomic Categories


Taxonomical categories is also called Liennean hierarchy or taxonomical hierarchy. It is the classification of organism in a definite sequence of categories in a definite sequence of categories from kingdom to species or from species to kingdom. There are seven categories:

Nomenclature


A single organism will be called in different names in different countries. Even in a single country it has several names in different regions, because of different languages. Another point is that some common names are quite misleading like, silver fish, jelly fish, star fish etc. are not true fishes. These problems can be resolved only when all living organisms are identified, classified and given scientific nomenclature.

Binomial system of nomenclature


The binomial system is system of classification developed by Carolus Linnaeus, a swedish naturalist. According to this system, each organism is given only one name consisting of two words. Linnaeus proposed scientific name of plants in his book “Species plantarum” and name of animals in his book “Systema naturae”.

Rules

  1. According to binomial system name of any organism consists of two components or words: Genetic name (name of genus) and Specific epithet (name of specis).
  2. In plant nomenclature tautonyms are not valid i.e. generic name and speific epithet should not be same. But tautonyms are valid in animal nomenclature. eg. Naja naja (Indian cobra) and Rattus rattus (Rat).
  3. First letter of generic name should be in capital letter and first letter of specific epithet should be in small letter.
  4. Scientific name should be derived from latin or greek languages because they are dead languages.
  5. When written with free hand or typed, then generic name and specific epithet should be separately underlined. But during printing name should be in italic to indicate their latin origin. 
  6. Name of the scientist (who proposed nomenclature) should be written in short after the species name. But name of scientist should be neither underlined nor written in italics. eg. Mangifera indica Linn.

Biological Organisation

The biological organisation starts with submicroscopic molecular level passes through microscopic level and ends up in ecosystem and the biosphere. Atom is the lowest unit at molecular level whereas the cell is the lowest unit at organism level. In the ecosystem, an individual forms the smallest unit.The organisation levels, below and above individual level, can be given as:

Biological Organization

Some Important Points:

  1. Water, glucose, carbon-dioxide, amino acids etc are micro-molecule.
  2. Carbohydrate, lipids, protein and nucleic acids etc. are macro-molecule.
  3. Carbohydrate is energy storage molecules.
  4. Lipid is major group of insoluble hydrocarbons having many functions
  5. Protein is structural and fundamental make up of cells
  6. Nucleic acid is information storage device of cells.

What is science?


By DRGP Biology

Science

Science is the systematic study that creates, builds and organizes knowledge in the form of testable explanations. The word 'science' is derived from a Latin word 'scientia', which means 'to know'. Science is a process that is used to answer the question about nautre. Science is a body of knowledge derived from observations and experiments, which are directed to determine the principles underlying what is being studied.

Steps of scientific method

  1. Observation
  2. Formation of Hypothesis
  3. Testing of Hypothesis
  4. Developing theory

Observation

It is simply the ability to notice something, keeping records and finding out answer for questions framed by the observer.

Formulation of Hypothesis

The next requirement is to develop a number of potential explanations or hypothesis based on the observation.

Testing Hypothesis

After developing hypothesis, we need to test the hypothesis. Generally, the scientists carry out an experiment for testing one or more hypothesis. Experiment helps to reject or accept the hypothesis.

Developing theory

If the repeated experiments to test a hypothesis of the prediction give the same result again and again the hypothesis gains validity. A hypothesis that survives repeated tests over a long period of time and that has central importance to an area of science, know considered as a theory.