Class 11 Biology Revision Notes for Transport in Plants of Chapter 11

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Plant transport various substances like gases, minerals, water, hormone and organic solutes to short distance (one cell to another) or long distance as water from roots to tips of stem.

• Long distance transport occurs through vascular system, xylem and phloem called translocation through mass flow.
• The direction of translocation may be unidirectional as in case of water and multidirectional as in minerals and organic solutes.

Simple Diffusion-

• Movement by diffusion is passive and slow along the concentration gradient through permeable membrane.
• No energy expenditure takes place. It occurs in liquid and gases.
• Rate of diffusion are affected by gradient of concentration, permeability of membrane, temperature and pressure.

Facilitated Diffusion-

• Lipid soluble particles easily pass through cell membrane but the hydrophilic solutes movement is facilitated.
• For facilitated diffusion, membrane possesses aquaporins or water channels. Aquaporins are membrane proteins for passive transport of water soluble substances without utilization of energy.
• The protein forms channels in membrane for molecules to pass through. The porins are proteins that forms huge pores in the outer membrane of the plastids, mitochondria etc.
• Water channels are made up of eight different types of aquaporins.

Symport, Antiport and Uniport-

• In Symport, both molecules cross the membrane in the same direction.
• In Antiport, both molecule moves in opposite direction.
• When a molecule moves across a membrane independent of other molecules, the process is called uniport.

Active Transport

• Uses energy to pump molecules against the concentration gradient. It is carried out by membrane proteins.
• In active transport movable carrier proteins are called pumps.
• The pumps can transport substance from low concentration to high concentration. The carrier proteins are very specific in what it carries across the membrane.

Comparison between Transport mechanisms-

Simple diffusion	Facilitated diffusion	Active transport
Special membrane protein is not required.	Special membrane protein is required.	Special membrane protein is required.
Not selective	Highly selective	Highly selective
Transport do not saturate	Transport saturate	Transport saturate
No uphill transport	Uphill transport	Uphill transport
No ATP energy is required.	No ATP energy is required.	ATP energy is required.

Plant Water Relationship

• Water is essential for all physiological activities of plants along with all living organisms. It provide medium for most substances to dissolve in it.
• Protoplasm of cells contains water in which different molecules are dissolved and suspended.
• Terrestrial plants take lot of water and release most of it in form of water vapour by the process of transpiration.
• Water is the limiting factor for plant growth and productivity in both agricultural and natural environments.

Water Potential (ΨwΨw)- is a concept fundamental to the understanding of water movement. Water potential is determined by solute potential (ΨsΨs) and pressure potential (ΨpΨp).

• Water molecules possess kinetic energy. The greater the concentration of water in the system, the greater is its kinetic energy or water potential. So pure water has greatest water potential.
• Water potential is denoted by Greek symbol Psi (ΨΨ) and is expressed in pressure unit Pascal (Pa).
• Water pressure of pure water is taken as zero at standard temperature and pressure. A solution has less water potential due to less water concentration.
• The magnitude of lowering of water potential due to dissolution of solute is called solute potential (ΨsΨs). Solute potential is always negative. More the solute molecules in the solution lesser the solute potential.
• If a pressure greater than atmospheric pressure is applied to pure water or solution, its water potential decreases. Pressure potential is usually positive. Pressure potential is denoted by (ΨpΨp).
• Water potential of a cell is affected by both solute and pressure potential. The relationship is as follows.

ΨwΨw = ΨsΨs + ΨpΨp
Ψw=Ψs+ΨpΨw=Ψs+Ψp
Osmosis is the diffusion of water across a semi-permeable membrane. The net direction and rate of osmosis depends upon the pressure gradient and concentration gradient. Water will move from its region of higher concentration to region of lower concentration until equilibrium is reached.

• Solute A has more water and less solutes so high water potential in comparison to the solution in B container.
• Osmotic potential is the pressure required to prevent water from diffusing. More the solute concentration greater will be the pressure required to prevent water from diffusing it.
• Numerically osmotic pressure is equal to osmotic potential but sign is opposite. Osmotic pressure is the positive pressure while osmotic potential is negative.
• If the surrounding solution balances the osmotic pressure of cytoplasm, the solution is called isotonic.
• If the external solution is more dilute than cytoplasm, it is hypotonic. The cells swell up when placed in hypotonic solution.
• If the external solution is more concentrated than cytoplasm, it is hypertonic. Cell will shrink in hypertonic solution.
• Plasmolysis is the shrinkage of the cytoplasm of the cell away from its cell wall under the influence of hypertonic solution. The pressure of plasmolysis is usually reversible when the cell is placed in hypotonic solution.
• The pressure build up against the wall due to movement of water inside is called turgor pressure. It is responsible for enlargement and extension growth of cells.
• Imbibition is a special type of diffusion when water is absorbed by solid colloids causing them to increase in volume. For example absorption of water by seeds and dry woods. Imbibition is also a kind of diffusion because movement of water is from higher concentration to lower concentration.
• Water potential gradient between the absorbent and liquid imbibed is essential for imbibition.

• Long distance transport of water in plants takes place by mass or bulk flow system. It is the movement of substance in bulk from one point to another as a result of pressure difference between two points.
• The bulk movement of substances through the conducting or vascular tissue of plants is called Translocation. Xylem is associated with translocation of water and mineral salts, some organic nitrogen and hormone from roots to aerial parts of plants.
• Phloem transport organic and inorganic solutes from leaves to other part of plants.

Absorption of water by plants

• Water is absorbed along with mineral solutes by root hairs by diffusion. The absorbed water passes to deeper layer by two pathways.

Apoplast pathway	Symplast pathway
It consists of nonliving parts of plants body such as cell wall and intercellular spaces.There is little resistance in movement of water.It is faster.Metabolic state of root does not affect apoplast pathway.	It consists of living parts of plant body such as protoplast connected to plasmodesmata.Some resistance occurs in the movement of water.It is slightly slower.Metabolic state of root directly affect symplast pathway.

• Most of the water flows in roots via apoplast pathway because cortical cells are loosely packed and offers no resistance to water movement.

• The inner boundary of cortex, endodermis is impervious to water due to suberised matrix called Casperian strip. Water molecules are directed through wall regions that are not suberised.
• Water flows through the different layers of roots to reach the xylem tissues as follows-

• A mycorrhiza is the symbiotic association between a fungus and angiospermic roots. The fungal filaments forms a network around the young root to have large surface area that help to absorb mineral ions and water from the soil. The fungus provide minerals and waters and roots in turn provide organic and nitrogen containing compounds.

Ascent of saps (Translocation of water)
The upward movement of water from roots towards the tips of stem, branches and their leaves is called ascent of sap.

• Vital force theory was forwarded by J.C.Bose in 1923. This theory believes that the innermost cortical cells of the root absorb water from the outer side and pump the same into xylem channels.
• Root pressure theory was forwarded by Priestley in 1916. Root pressure is positive pressure that develops in the xylem sap of the root of plants. It can be responsible for pushing up water to small heights in plants.
• Loss of water in liquid phase by herbaceous plants from the tips of leaf blades is known as guttation.
• Water rises in tubes of small diameters, kept in vessels having water due to force of surface tension. Similarly water rises up in the walls of xylem channels due to adhesion and cohesion. This theory is called Theory of Capillarity.
• Cohesion Tension theory was put forwarded by Dixon and Joly in 1894. According to this theory water is mostly pulled due to driving force of transpiration from the leaves. The water molecules remain attached with one another by cohesion force. The water molecule does not breaks in vessels and tracheid due to adhesive force between their walls and water molecules. On account of tension created by transpiration, the water column of plant is pulled up passively from roots to great heights.
• Transpiration is the loss of water in the form of water vapour from aerial parts of plants. The following purpose is fulfilled by transpiration-

1. Creates transpirational pull for absorption and transport in plants.
2. Supplies water for photosynthesis.
3. Transport minerals and salts from soil to other parts of plant.
4. Cool the leaves and maintain their shape and size.

• Photosynthesis is limited by available water. C4C4 plants are twice as efficient as C3C3 plants in term of fixing carbon. Although C4C4 plants uses half as much water as C3C3 plants for the same amount of CO2CO2 fixed.

Uptake and transport of mineral nutrients

• Most of the minerals enter the roots by active absorption into the cytoplasm of epidermal cells because-

1. Minerals are present in the soil as charged particles (ions) which cannot move across cell membranes.
2. The concentration of ions in soil is usually lower than concentration in roots.

• Active absorption needs energy in form of ATP. Active uptake of ions is also responsible for water potential gradient in roots.
• Transport proteins of epidermal cells are control point where quantity and type of solutes that reach the xylem is adjusted.
• The ions that reaches to xylem by active or passive transport moves further upward along with transpirational pull.
• The chief sink of mineral elements are growing region of plants like apical meristem, young leaves, growing flower and fruit, and the storage organs.
• Minerals are frequently remobilized from older senescing part of the plants to young growing parts of plant.
• The elements most readily mobilized include phosphorus, sulphur, nitrogen and potassium. The element like calcium is not mobilized as it is the structural components of plant body.

Phloem transport: Flow from Source to Sink

• Food (sucrose) is transported by phloem from source to sink. The part of plant that synthesize the food is called source and part where food is used or stored is called sink.
• The source and sink can be reversed by the plants depending upon the season or plant’s need. So, the direction of movement in the phloem is bi-directional.
• Phloem sap is mainly water and sucrose but other sugars, hormones and amino acids are also translocated through it.

Pressure flow or Mass flow hypothesis

• It is the most accepted theory for the translocation of sugar from source to sink. Glucose is prepared at source by photosynthesis which is converted into disaccharides (sucrose). Sucrose moves into companion cells and then into sieve tube cells by active transport.
• Loading of phloem at source creates a water potential gradient that facilitates the mass movement in the phloem.
• Sieve tube cells of phloem forms a long column with holes in their wall called sieve plates. Cytoplasmic strands pass through the hole in the sieve plates to form continuous filament. Hydrostatic pressure developed in sieve tube cells moves the sap in the phloem.
• At sink, incoming sugar is actively moved out of the phloem as complex carbohydrates. The loss of solute produces a high water potential in the phloem and water passes out and returning into xylem.

Class 11 Biology Revision Notes for Cell Cycle and Cell Division of Chapter 10

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• The sequence of events by which a cell duplicates its genome, synthesizes the other constituents of cells and eventually divides into two daughter cells is called cell cycle.
• DNA synthesis occurs in one specific stage of cell division but distribution of chromosome in cells occurs in complex series of events during cell division.

Phases of Cell cycle
Human cell divides once in approximately 24 hours, which may vary in different organisms. In yeasts it takes about 90 minutes to complete the cell division process.
Cell cycle is divided into two basic phases-

1. Interphase– it is the phase between two successive M phases. Interphase lasts for 95% of a cell cycle. This phase is called as resting phase but during this period the cells prepare itself for nuclear division by cell growth.
2. M Phase– when the actual cell division or mitosis occurs. It starts with karyokinesis (nuclear division) or duplication of chromosome and end with cytokinesis or division of cell matrix (cytoplasm division).The interphase is divided into three further phases:

• G1 phase represents the interval between mitosis and initiation of DNA replication. Cell is continuously active and grows in size.

• During synthesis phase, replication or synthesis of DNA takes place and amount of DNA get doubles per cell.
• During G2 phase protein is synthesized in preparation for mitosis.
• In adult animals, some cells do not divide or may divide occasionally. These cells do not divide further and exits the G1 phase to enter an inactive stage called Quiescent Stage (G0) of cell cycle.
• In animals mitotic division is present in only somatic diploid cells but in plants it is seen in both haploid and diploid cells.
• Mitosis cell division is also known as equational division because the numbers of chromosome remain same in parental and progeny cells.

• Prophase is the first phase of mitosis followed by G2 phase. It involves following events-

1. Initiation of condensation of chromosomal materials.
2. Movement of centrioles towards opposite poles of the cell.
3. At the end of prophase, endoplasmic reticulum, nuclear membrane, Golgi complex disappears.

• Metaphase starts with complete disappearance of nuclear membrane. The most suitable stage for study of morphology of chromosomes. It involves

1. Condensation of chromosomal materials in to compact and distinct chromosomes made up of two sister chromatids attached with spindle fibres with kinetochores.
2. Chromosomes arrange at centre of cell called metaphase plate.

• Anaphase involves following steps:

1. Splitting of each chromosome at centromere into two sister chromatids.
2. Two chromatids start moving towards opposite poles.

• Telophase is the last stage of mitosis which involves

1. Chromosomes reach at opposite poles and loose its identity as discrete unit.
2. Nuclear membrane reassembles around the chromosome clusters.
3. Nucleolus, Golgi complex and ER reappear.

• Cytokinesis is the division of cytoplasm of a cell after karyokinesis (division of chromosome) into two daughter cells. In animal cells, appearance of furrows in plasma membrane that deepens gradually and joins to divide cytoplasm into two parts.
• In plant cells, wall formation starts at the centre and grows outwards to meet lateral walls. The formation of cell wall begins with formation of cell plate.

Significance of Mitosis

1. Mitosis produces diploid daughter cells with identical genetic complement.
2. It helps in repair of cells, especially in lining of gut and blood cells.
3. Meristematic division in apical and lateral cambium results in continuous growth of plants.

Meiosis- The cell division that reduces the number of chromosome into half and results in the production of haploid daughter cells is called meiosis. It helps in production of haploid phase in the life cycle of sexually reproducing organism. It involves following events.

1. Two sequential cycles of nuclear and cell division called meiosis I and meiosis II but single cycle of DNA replication.
2. It involves pairing of homologous chromosome and recombination of them.
3. Four haploid cells are formed at the end of meiosis II.

Meiosis I	Meiosis II
Prophase I	Prophase II
Metaphase I	Metaphase II
Anaphase I	Anaphase II
Telophase I	Telophase II

• During Leptotene, the chromosome becomes distinct and visible under microscope. Compaction of chromosome continues throughout the leptotene phase.
• During Zygotene stage, chromosomes start pairing together (synapsis). The paired chromosomes are called homologous chromosome. Synaptonemal complex formed by a pair of homologous chromosome is called bivalent or a tetrad.
• During Pachytene stage, crossing over between non-sister chromatids of homologous chromosome occurs for exchange of genetic materials. The crossing over is enzyme –mediated process which involves enzyme recombinase.
• Diplotene is recognized by dissolution of synaptonemal complex and tendency to separation of bivalent except at the site of crossing over. This forms an X like structure called chiasmata.
• Diakenesis is marked by terminalisation of chiasmata. The nuclear membrane breaks and nucleolus disappear.
• In metaphase I the bivalent chromosome align at equatorial plate and microtubules from the opposite poles of the spindle get attached to the pair of homologous chromosomes.
• Anaphase I – homologous chromosome separate but sister chromatids remain attached at centromere.

• During Telophase I, nuclear membrane and nucleolus reappears and cytokinesis follows. This is called as diad of the cells.
• The stage between two meiotic divisions is called interkinesis and it is short lived that follows Prophase II.

Meiosis II

• It is initiated immediately after cytokinesis before chromosome gets elongated.
• In prophase II, nuclear membrane disappears and chromosome becomes compact.
• At metaphase II stage, the chromosomes align at equator and microtubules attach with kinetochores of sister chromatids.
• Anaphase II start with splitting of centromere of each chromosome to move towards opposite poles.

• Meiosis ends with Telophase II in which two groups of chromosomes get enclosed by nuclear membrane followed by cytokinesis to form tetrad of cells (four haploid daughter cells).

Significance of meiosis–

1. Meiosis forms the gametes that are essential for sexual reproduction.
2. Crossing over introduces new recombination of traits.
3. Helps in maintenance of chromosome number of sexually reproducing organism.
4. Provides evidence of basic relationship of organisms.

Difference between Mitosis and meiosis

Mitosis	Meiosis
Takes place in the somatic cells.It is a single division which produces two cells.Haploid and diploid both kind of cells may undergo mitosis.Crossing over absent.Pairing of chromosome does not occur.	Takes place in reproductive cells.It is a double division which produces four cells.Only diploid cells undergo meiosis cell division.Crossing over takes place.Pairing of homologous chromosome occurs.

Class 11 Biology Revision Notes for Biomolecules of Chapter 9

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• Chemicals or molecules present in the living organism are known as biomolecules. Biomolecules are divided into two types- inorganic and organic.
• Inorganic biomolecules includes minerals, gases and water and organic biomolecules includes carbohydrates, fats, proteins, nucleic acids, vitamins, etc.
• Different biomolecules can be classified as aldehyde, ketones and aromatic compounds as chemical forms. The amino acids, nucleotides and fatty acids can be classified as biochemical forms.

• Except lipids, macromolecules are formed by polymerization of sub-units called monomers.
• Proteins are polymers of amino acids. Amino acids are linked by peptide bond formed by dehydration between COOH group of one amino acids and NH3 group of next with the removal of H2O.

• In nucleic acids, the phosphate molecules links 3’ C of sugar of one nucleoside to the 5’ C of sugar of next nucleosides releasing two water molecules to form 3’-5’ phosphodiester bond.
• In polysaccharides, the mono-saccharides are linked by glycosidic bonds formed by dehydration between two carbon atoms of two adjacent monosaccharides.

Carbohydrates (Polysaccharides)

• Polysaccharides are long chain of sugar containing different monosaccharaides as a building block.

• Starch is present in plants as store house of energy. It forms helical secondary structure. It can hold the I₂ molecules in the helical structure.
• Cellulose molecules contain glucose molecules joined together by 1-4 β linkage. It is the most abundant organic molecules on earth.
• Glycogen is called animal starch as it is the reserve food materials for animals, bacteria and fungi. In this, glucose molecules are arranged in highly branched bush like chain having two types of linkage 1-4 α in straight chain and 1-6 linkage in branching.

Proteins are polypeptide chains made up of amino acids. There are 20 types of amino acids joined together by peptide bond between amino and carboxylic group. There are two kinds of amino acids-

1. Essential amino acids are obtained by living organism along with food.
2. Non-essential amino acids can be prepared by our body from raw materials.

• The main functions of protein in living cell are

1. Transport of nutrient across the membrane.
2. Fight infectious organisms.
3. Produce enzyme and proteins.

• Collagen is the most abundant protein in animal world.

• Primary structure of protein is the basic structure of protein in which a number of polypeptides are involved having sequence of amino acids. The first amino acid of sequence is called N-terminal amino acid and last amino acid of peptide chain is called C-terminal amino acid.

• Secondary structure protein threads forms helix. There are three types of secondary structure- α helix, β pleated and collagen. In α helix, the polypeptide chain is coiled spirally in right handed manner.
• In β pleated secondary proteins two or more polypeptide chains are interconnected by hydrogen bonds. In collagen there are three strands or polypeptides coiled around one another by hydrogen bonds.
• In Tertiary structure long protein chain is folded upon itself like a hollow woollen ball to give three dimensional view of protein.

(a) secondary structure (b) Tertiary structure

• In Quaternary structure each polypeptide develops its own tertiary structure and function as subunit of protein. Eg. Hemoglobin. In adult human hemoglobin 4 sub-units are involved. The two subunits are of α type and two subunits of β types.

Nucleic Acid: Nucleic acids are polynucleotides. A nucleic acid has three chemically distinct components- heterocyclic compound ( nitrogenous base), polysaccharides ( ribose/ deoxy-ribose sugar) and phosphate or phosphoric acid.

• The sugar found in nucleic acid is either ribose or deoxyribose. Nucleic acid containing deoxyribose sugar is called DNA (Deoxyribonucleic Acid) and those containing ribose sugars are called RNA (Ribonucleic acid).
• Biomolecules are constantly being changed into some other biomolecules and also made from other biomolecules. This breaking and making is through chemical process called metabolism.
• In living organism, all the metabolic reactions are enzyme catalyzed. Catalysts are those substances that alter the rate of reaction. The protein with catalytic power is called enzyme.

Metabolic Basis for living organism

• The metabolic pathways that lead to more complex structure from simpler structure are called biosynthetic or anabolic pathways and those pathways that lead to simpler structure from complex structure are called catabolic pathways.
• Photosynthesis and protein synthesis are example of anabolic pathway. Respiration and digestion are examples of catabolic pathway.
• ATP (adenosine triphosphate) is the most important form of energy currency in living world.
• All living organism exist in steady state characterized by concentration of each of the metabolites. The living state is a non-equilibrium steady state to be able to perform work.

Enzymes

• Enzymes are commonly proteinaceous substances which are capable of catalysing chemical reactions of biological origin without themselves undergoing any change. They are commonly called as biocatalysts.
• The nucleic acids that behave like enzymes are called ribozymes.

• The tertiary structure of protein/Enzyme has pockets or crevice into which substrate fit to form ES complex.
• The formation of the ES complex is essential for catalysis.
  E + S       ES →EP →E + P
• The structure of substrate gets transformed into the structure of product through formation of transient state structure.
• The major difference between inorganic and organic catalyst is inorganic catalyst works effectively at high temperature and pressure but enzyme get damaged at high temperature.
• The external energy required to start a chemical reaction is called activation energy.

Factors influencing Enzyme Activity

1. Temperature- An enzyme is active within a narrow range of temperature. Temperature ate which enzyme is most active is called optimum temperature. The enzyme activity decrease above and below this temperature.

2. pH – every enzymes has an optimum pH at which it is maximum active. Most of the
intracellular enzymes work at neutral pH.
3. Concentration of Substrate– increase in substrate concentration increases the rate of
reaction due to occupation of more active sites by substrate.

Competitive Inhibitor- when the molecular structure of inhibitor resembles the substrate, it inhibits the function of enzymes.
Enzymes are classified as
1.  Oxidoreductases/Dehydrogenases–
S reduced + S’ oxidised →→ S oxidised + S’ reduced
2.  Transferases
S – G + S’ →→ S + S’ – G
3. Hydrolases catalyses the hydrolysis of peptide, ester, glycosidic bonds et
4. Lyases remove the groups from substrate.

5. Isomerases-inter conversion of optical, geometrical or positional isomers.
6. Ligases – catalyses the linking together of two compounds.
Co-factors are the non-protein constituent of an enzyme which make the enzyme more catalytically active. The protein portions of enzyme are called apoenzyme.

Prosthetic groups are organic compounds and are tightly bound to the apoenzyme. For
example, in peroxidase and catalase, which catalyze the breakdown of hydrogen peroxide, haem is the prosthetic group
The essential chemical components of any coenzymes are vitamins. Example, coenzyme NAD and NADP contain the vitamin niacin

Class 11 Biology Revision Notes for Cell: The Unit of Life of Chapter 8

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• Study of form, structure, and composition of cell is called cytology.
• Cell is the structural and functional unit of life. In unicellular organism (amoeba, paramecium, yeast, bacteria) single cell performs all the essential functions of life.
• In multicellular organism, different kinds of tissues perform different function and have division of labour.
• Anton Von Leeuwenhoek first saw and described a live cell. Robert Brown later discovered the nucleus.
• Metthias Schleiden and Theodore Schwann( 1938) proposed the cell theory which was later modified by Rudolf Virchow(1855)-

1. All living organisms are composed of cells and products of cells.
2. All cells arise from pre-existing cells.

Prokaryotic cells	Eukaryotic cells
Membrane bound nucleus is absent.Cells are smaller in size.Single chromosome is present.Membrane bound organelles are absent.	Membrane bound nucleus is present.Cells are larger in size.More than one chromosome is present.Membrane bound organelles are present.

Shape and size of cells varies greatly according to their position and function. Mycoplasma is the smallest cell and largest isolated cell is the ostrich egg. The shape of cell may be cuboid, columnar, polygonal, thread like or irregular.
Prokaryotic Cells

• Prokaryotic cells are represented by Bacteria, Blue green algae, Mycoplasma and PPLO. They multiply rapidly and vary in size greatly.
• Bacterial cells may be Bacillus (rod shaped), Coccus (spherical), Vibrio (comma-shaped) and Spirillum (spiral).
• All prokaryotic cells have cell wall surrounding the cell membrane except in Mycoplasma. Genetic material is naked.
• The plasmid DNA, in some bacteria provides some special features like resistance to antibiotics.
• Cell organelles like Mitochondria, Golgi bodies etc. are absent in prokaryotes. A specialized differentiated cell membrane called Mesosome is the characteristic of prokaryotes.

• In bacterial cell a chemically complex cell envelope is present, which consist of three layers. The outermost is Glycocalyx, middle one cell wall and inner innermost is the cell membrane.
• Glycocalyax may be as loose sheath in some bacteria called slime layer. In some other bacteria Glycocalyx may be thick and tough called capsule.
• Plasma membrane is semi-permeable having mesosome in the form of vesicles, tubules and lamellae. They help in cell wall formation, DNA replication and distribution to daughter cells.
• Motile bacterial cell contain flagella, which is composed of filament, hook and basal body. Pili and fimbriae are the other surface structures that help the bacteria to attach with host and other substances.
• In prokaryotes, ribosome are attached with cell membrane having two sub-units – 50S and 30S to form together 70S prokaryotic ribosomes.
• Ribosomes are site of protein synthesis. Ribosomes attached with mRNA to form a chain are called polyribosomes.
• Reserved materials in prokaryotic cells are present in cytoplasm as cell inclusion bodies, which may contain phosphate, granules, glycogen granules etc.
• Gas vacuoles are found in blue green algae and purple and green photosynthetic bacteria.

Eukaryotic Cell

• Eukaryotic cells are present in Protista, plants, Animals and Fungi. Cytoplasm is divided into compartments due to presence of membrane bounded organelles.
• The cells contain well organized nucleus with nuclear membrane. The genetic materials are arranged in chromosomes.
• Plants cells differ in having cell wall, plastids and large central vacuole as compared to animal cells. Animal cells have centrioles, which are absent in plant cells.

Plant cell

Animal cell

• Cell membrane is composed of lipids that are arranged in bilayer. The lipid component is mainly composed of phosphoglycerides. Later it was found that protein is also present in cell membrane. Ratio of protein and lipids varies in different cells.
• Membrane protein may be integral or peripheral. Integral protein remains buried in membrane but peripheral protein lies on the surface.
• Singer and Nicholson (1972) proposed fluid mosaic model. According to this model the quasi-fluid nature of lipid enables lateral movement of protein within the bilayer of lipids.

• The main function of plasma membrane is the transport of molecules across it.

Active Transport	Passive Transport
The transport involves an expenditure of energy by the cells.It occurs against the concentration gradient.It is a rapid process.	The cells do not spend energy in passive transport.This transport is always along the concentration gradient.It is comparatively slow process.

• The movement of water from higher concentration to lower concentration by diffusion is called osmosis.
• Cell wall is present in plant cells and fungi. Algae have cell wall made up of cellulose, galactans and minerals like calcium carbonate. In other plants it consists of cellulose, hemicellulose, pectin and proteins.
• Primary cell wall of young plant is capable of growth, which diminish in mature cells. Secondary cell wall is formed on inner side of the cells.
• Plasmodesmata connects the cytoplasm of neighboring cells.
• Endomembrane system of cell includes endoplasmic reticulum, golgi complex, lysosomes and vacuoles.

• Endoplasmic Reticulum are the tubular structure scattered in the cytoplasm.

1. Rough endoplasmic reticulum bears ribosomes on its surface. RER is involved in protein synthesis and secretion.
2. Smooth endoplasmic reticulum does not bear ribosomes on its surface. SER is involved in lipid synthesis and steroidal hormones.

• Golgi apparatus was first observed by Camillo Golgi in 1898 near nucleus. They consist of many flat, disc-shaped sacs or cisternae stacked parallel to each other.
• Golgi apparatus performs the function of packaging of materials and its transportation. A number of protein synthesized by ribosomes are modified in cisternae of golgi apparatus. Golgi apparatus is the site for synthesis of Glycoprotiens and glycolipids.

• Lysosomes are membrane bound vesicular structures formed by the process of packaging in the Golgi apparatus. They are rich in hydrolytic enzymes- lipase, protease, carbohydrases active at acidic PH. These enzymes are capable of digesting carbohydrates, proteins, lipids and nucleic acids.
• Vacuoles are membrane bound space found in cytoplasm containing water, sap and excretory product. They are bound by single membrane. They form contractile vacuole and food vacuole in many organisms.
• Mitochondria is double membrane bound structure with the outer membrane and inner membrane dividing its lumen in two compartments. The inner membrane forms a number of infoldings called cristae towards the matrix.

• Two membranes have their own specific enzyme.
• Mitochondria are sites for aerobic respiration. They produce cellular energy in form of ATP so, they are called power house of the cells. The matrix of mitochondria also contain circular DNA molecules, a few RNA molecules, ribosomes and components of protein synthesis.
• Plastids are found in plant cells and in Euglenoids.

• Chloroplast contains chlorophyll that traps solar energy for photosynthesis. Chromoplast provides yellow, orange and red colours to different parts of plants.
• Leucoplasts are colourless plastids that store food, amyloplasts (carbohydrates), elaioplasts (oils) and aleuroplasts (proteins).
• Chloroplasts are double membrane structures. The space limited by inner membrane is called stroma. Thylakoids are present in stroma as stacks like the piles of coins called grana.

• Stroma contain enzymes for synthesis of protein and carbohydrates. Double strand circular DNA and ribosomes are also present in stroma.
• Eukaryotic cells have 80S ribosomes. They have granuler structure with two subunits.
• Centrosome is an organelles containing two cylindrical structures called centrioles. Each centrioles is made up of 9 fibrils of tubulin protein. Central part of centriole is called hub and peripheral fibrils are called spokes .
• Nucleus has highly extended, elaborate nucleoprotein fibres called chromatin, nuclear matrix and nucleoli. The outer membrane is continuous with endoplasmic reticulum and bears ribosomes.
• The chromatin materials change into chromosome during active cell division. It consists of DNA and histone proteins.
• Every chromosome has a primary constriction or the centromere, on the sides of which disc shaped kinetochores are present.

• On the basis of position of centromere chromosomes are of following types-

Some chromosomes have non-staining secondary constriction at certain location. This gives a small fragment called satellite.

Class 11 Biology Revision Notes for Structural Organisation in Animals of Chapter 7

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In multicellular organism a group of similar cells along with intercellular substances perform a specific function. Such organization is called tissue.

Epithelial Tissue: This tissue provides covering or lining for some part of the body. Cells are compactly packed without intercellular space.

• Simple epithelium is composed of single layer of cells and function as lining of body cavities, ducts and tubes.
• The compound epithelium consists of two or more than two layers of cells and has protective function.
• The squamous epithelium is made up of single layer of flattened cells with irregular boundaries. They are present in lining of blood vessels, air sacs of lungs.
• Cuboidal epithelium is made up of single layered cube-like cells and found in ducts of glands and tubular part of nephron of kidney for absorption and secretion.
• Columnar epitheliums are made up of tall and slender cells. The nuclei are located at the base. Free surface may have microvilli found in lining of stomach and intestine. The ciliated one are called as ciliated epithelium.
• Columnar and cuboidal epithelium specialized for secretion are known as glandular epithelium, which may be unicellular as in goblet cells of alimentary canal or multicellular as in salivary gland.

Endocrine glands	Exocrine glands
Endocrine gland secretes hormones.Products are directly released at target sites through blood.	Secretes enzymes, milk, mucus, saliva etc.Products are released through ducts.

• Main function of compound epithelium tissue is to provide protection against chemical and mechanical stress. They cover the dry surface of skin, moist surface of buccal cavity, etc.
• Epithelial cells are held together by intercellular material to form specialized junction.

Connective Tissues: They are most abundant and widely distributed tissues which link and support the other tissues. All connective tissues except blood cells, secrete fibres of structural protein called collagen or elastin to provide elasticity and flexibility.

• Loose Connective Tissues contain cells and fibres loosely arranged in semi-fluid ground substance. It includes areolar tissue and adipose tissue.

Areolar Connective Tissue	Adipose Connective Tissue
It contains fibroblast, macrophages and mast cells.It acts as support framework for epithelium.	Fibroblast, macrophages and mast cells are absent.The cells are specialized to store fats beneath the skin.

• Dense connective Tissue contains fibres and fibroblast compactly packed. The orientation of fibres may be regular or irregular pattern.
• In dense regular connective tissues collagen fibres are present in rows between parallel bundles of fibres as in tendons and ligaments.

Tendon	Ligament
Tendon connects bones to skeletal muscles.It is made up of white fibrous tough tissue.	Ligament connects one bone to another bone.It is made up of yellow elastic tissue with collagen fibres.

• Cartilage, bones and blood are specialized connective tissue.

Cartilage	Bone
They are soft skeletal tissue.Chondriocyctes are enclosed in small cavities with matrix.They are present in tips of nose, outer ear, between vertebral bones.	Bones are hard skeletal tissue.They are rich in Calcium salt and collagen fibres.They form the skeletal framework of vertebrates like limbs, legs, etc.

• Blood is fluid connective tissue containing plasma, red blood cells, white blood cells and platelets. It helps in transportation of various substances between organs.

Muscle Tissue

• Each muscle is made up of long cylindrical fibres arranged parallel to each other. Fibres are composed of fine fibrils called myofibrils. Muscle fibres contract and relax in response to stimulation.

Skeletal	Smooth	Cardiac
They are also known as striated, voluntary muscles.Multinucleated with light and dark bands.They are attached with bones.They are fibrous and un-branched, cylindrical in shape.	They are known as unstriated or involuntary muscles.They are uninucleate without bands.They are present in vessels, oesophagus.They are fibrous and un-branched, spindle shaped.	They are known as heart muscles and involuntary in nature.Uninucleate with faint light and dark bands.They are present in wall of heart.They are fibrous and branched, cylindrical in shape.

Neural Tissue

• The unit of neural system is neuron. Neuroglial cell protects and supports the neuron.
• When neuron get stimulated, electrical impulses are generated that travel along the plasma membrane (axon).

The tissues organize to form organs which in turn associate to form organ system in multicellular organisms.
Earthworm

• Earthworm is reddish brown terrestrial invertebrate that lives in upper layer of moist soil. The common Indian earthworms are Pheretima and Lumbricus.
• Earthworms have long cylindrical body divided into segments called metameres. The ventral surface contain genital pore and dorsal surface contain mid dorsal line.
• First body segment is called peristomium which contain mouth. 14-16 segments are covered by dark band called clitellum.

• Single genital pore is present on mid ventral line of 14th segments. A pair of male genital pore is present on 18th segment on ventro-lateral side.
• All the segment except 1st , last and clitellum contain S-shaped setae for locomotion.
• Alimentary canal is straight tube from 1st to last segment having, buccal cavity, muscular pharynx, oesophagus that leads to gizzards, which help in grinding the soil particles and decaying leaves. Stomach and small intestine leads to anus.
• Between 26-35 segments, the intestine has an internal median fold called typhlosole. This increases the effective area of absorption in the intestine.
• Closed vascular system consists of heart, blood vessels and capillaries. Blood glands are present on the 4th, 5th and 6th segments. They produce blood
  cells and haemoglobin which is dissolved in blood plasma.
• Earthworms lack respiratory organs and respire through moist skin.
• Excretory organs is coiled segmental tubules called nephridia. There are three types of nephridia: Septal nephridia, integumentary nephridia and pharyngeal nephridia.
• Nervous system is represented by ganglia arranged segmentwise on the ventral
  paired nerve cord. The nerve cord in the anterior region (3rd and 4th segments) bifurcates and joins the cerebral ganglia dorsally to form a nerve ring.
• Earthworm is hermaphrodite. Two pairs of testis is present in 10th and 11th segment. Prostrate and spermatic duct open to surface as male genital pore on 18th segment.
• One pair of ovaries is attached to the intersegmental septum of 12th and 13th segments. Female genital pore open on ventral side of 14th segment. Mutual exchange of sperms takes place during mating.

• Mature sperms and egg cells along with nutritive materials are deposited in cocoon in the soil where fertilisation takes place.
• Earthworms are known as friends of farmer because they make burrows in soil to make it porous for respiration and root penetration. Earth worms are also used for vermicomposting and as bait in game fishing.

Cockroach(Periplaneta americana)

• Cockroaches are nocturnal omnivorous organisms that lives in damp places everywhere. The body of cockroach is segmented and divisible into head, thorax and abdomen. The body is covered by hard chitinous exoskeleton.

• Head is triangular in shape formed by fusion of six segments to show flexibility. Head bears compound eyes. Antenna attached on head help in monitoring the environment.
• Thorax consists of three parts- prothorax, mesothorax and metathorax. Forewings and hind wings are attached with thorax. Abdomen consists of 10 segments.

Male Cockroach	Female Cockroach
The abdomen is long and narrow.Brood pouch is absent.Male have longer antenna.Anal styles are present.	The abdomen is short and broad.Brood pouch is present.Female have shorter antennae.Anal styles are absent.

Digestive System of Cockroach-

• Alimentary canal is divided into foregut, midgut and hindgut. Food is stored in crop. Gizzard help in grinding the food particles.

• At the junction of midgut and hindgut yellow coloured filamentous Malpighian tubules are present which help in excretion.
• Blood vascular system is open type having poorly developed blood vessels. The haemolymph is made of colourless plasma and haemocytes.
• Respiratory system consists of network of trachea which open through 10 pairs of spiracles on lateral side.
• The nervous system of cockroach consists of a series of fused, segmentally arranged ganglia joined by paired longitudinal connectives on the ventral side. Three ganglia lie in the thorax, and six in the abdomen. The nervous system of cockroach is spread throughout the body.
• Each compound eye of cockroach consists of about 2000 hexagonal ommatidia.
  With the help of several ommatidia, a cockroach can receive several images of an object. This kind of vision is known as mosaic vision with more sensitivity but less resolution,
• Cockroaches are dioecious. Male reproductive system consists of a pair of testes one lying on each lateral side in 4th-6th abdominal segments. The female reproductive system consists of two large ovaries situated on 2nd -6th abdominal segments.

 
Male reproductive system / Female reproductive system

• The fertilized eggs are encased in capsule called ootheacea. 9 to 10 ootheace are produced by each female.
• Cockroaches are pests and destroys the food, contaminate with smelly excreta.

Frog (Rana tigrina)
Frogs are cold-blooded organism having ability to change colours to hide from enemies. Body is divisible into head and trunk, bulged eyes covered by nictitating membrane. Male frog is different from female having vocal sacs and copulatory pad on first digit of forelimb.

• Digestive system consists of alimentary canal and digestive glands.

• Digestion starts in stomach and final digestion occurs in small intestine. Digested food is absorbed by villi and microvilli present in the inner wall of small intestine.
• Skin acts as aquatic respiratory organs (cutaneous respiration). On lands skin, buccal cavity and lungs acts as respiratory organs.
• The vascular system of frog is well-developed closed type. Heart is 3-chambered. Blood consist of plasma, RBC, WBC and Platelets.
• Frogs have a lymphatic system consisting of lymph, lymph channels and lymph nodes.
• The elimination of nitrogenous wastes is carried out by a well developed excretory system. The excretory system consists of a pair of kidneys, ureters, cloaca and urinary bladder. The frog excretes urea and thus is a ureotelic animal.
• The system for control and coordination is highly evolved in the frog. It
  includes both neural system and endocrine glands
• Frogs have well organised male and female reproductive systems. Male reproductive organs consist of a pair of yellowish ovoid testes, which are found adhered to the upper part of kidneys by mesorchium.
  The female reproductive organs include a pair of ovaries which are situated
  near kidneys.
• Fertilisation is external and takes place in water. Development involves a larval stage called tadpole. Tadpole undergoes metamorphosis to form the adult.

Reproductive systems of frog-
 
Male / Female

Class 11 Biology Revision Notes for Anatomy of Flowering Plants of Chapter 6

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Anatomy is the study of internal structure of organism. Study of plant anatomy includes histology- study of organization and structure of tissues. Anatomy helps in knowing the structural peculiarities of different group of plants and indicates the structural adaptation to diverse environments.
The tissue
A group of cells having a common origin and usually performing common function are called tissues.

• Meristematic tissue is a simple tissue composed of group of similar and immature cells which can divide and form new cells. The meristem which occurs at tips of roots and shoots are called apical meristem.
• Intercalary meristem occurs between mature tissues especially in grasses.Both apical meristems and intercalary meristems are primary meristems because they appear early in life of a plant and help to form the primary plant body.
• The meristem which occurs on the sides and takes part in increasing girth of the plants are called Lateral meristem. Intrafascicular cambium in the primary lateral meristem. Vascular cambium, cork cambium are secondary meristem.
• The cells that have become structurally and functionally specialized and lose the ability to divide are called permanent tissue. Permanent tissues having all cells similar in structure and function are called simple permanent tissues and those having different kinds of cells are called complex tissue.
• Parenchyma is a simple permanent living tissue which is made up of thin-walled  isodiametric cells. Each cell encloses a large central vacuole and peripheral cytoplasm containing nucleus. They are found in non-woody and soft areas of stem, root, leaves, fruits and flowers. They store the food and provide turgidity to softer parts of plant.

• Collenchyma consists of cells which are much thickened at corner due to cellulose, hemicellulose and pectin. Oval, spherical or polygonal often contain chlorophyll. They provide mechanical support to the growing parts of the plants like young stem.

• Sclerenchymas are supportive tissue having highly thick walled cells with little or no protoplasm due to deposition of cellulose or lignin. They are of two types: fibres and sclereids. They provide mechanical support to mature plant organs to tolerate bending, shearing, compression etc.

Complex Tissues– Xylem and phloem constitute the complex tissues in plants and work together as a unit.

Xylem	Phloem
It conducts water or sap.Xylem is found deep in the plant.Xylem provides mechanical strength.Xylem is made up of vessels, tracheid, xylem fibre and xylem parenchyma.	Phloem conducts organic food.It is situated towards the outer side.It has no mechanical functions.Phloem is made up of sieve tube, companion cells, phloem parenchyma and phloem fibres.

• Primary xylem is of two types- protoxylem and metaxylem. In stem, protoxylem lies in centre and metaxylem towards periphery. This type of primary xylem is called endarch.
• In roots, protoxylem lies in periphery and metaxylem lies towards the centre. This type of primary xylem is called exarch.
• In gymnosperms, albuminous cells and sieve cells lack sieve tube and companion cells.

Epidermal Tissue System

• It forms the outermost covering of whole plant body, which consists of epidermal cells, stomata, epidermal appendages (trichomes and hairs).
• Epidermis is single layered, parenchymatous with waxy thick layers of cuticle to prevent water loss.
• Stomata is present in epidermis of leaves. It regulates the transpiration and gaseous exchange. In dicots, stomata are bean-shaped having two guard cells closing the stomatal pore. In monocots, stoma is dumbbell-shaped. Guard cells contain chloroplasts and help in opening and closing of stomata.
• Guard cells are surrounded by subsidiary cells. The stomatal aperture, guard
  cells and the surrounding subsidiary cells are together called stomatal apparatus

Dicots (Bean shaped) Monocots (Dumb-bell shaped)

• Epidermis also contains a number of hairs. Root hairs are unicellular elongation of epidermal cells. Trichomes are present on stems, which are multicellular, branched or un-branched preventing water loss due to transpiration.

The ground Tissue System

• All the tissue between epidermis and vascular bundle forms the ground tissues. It consists of simple permanent tissues. Parenchyma is present in pericycle, cortex, pith and medullary rays in stem and roots.
• In leaves the mesophyll, chloroplast containing cell, forms the ground tissues.

The Vascular Tissue System

• The vascular system consists of complex tissues, xylem and phloem that together form vascular bundles.

• When xylem and phloem within a vascular bundle are arranged in alternate manner on different radii, the arrangement are called radial as in roots. When xylem and phloem are situated at the same radius of vascular bundle, it is called conjoint as in stem and leaves.

Radial
Dicotyledonous Root

• The outermost layer of dicot root is epidermis containing unicellular root hairs.
• The cortex consists of several layers of thin-walled parenchyma cells.
• The innermost layer of cortex is called endodermis having waxy material suberin as casparian strips, which is impermeable to water.

Monocotyledonous Root

• The anatomy of the monocot root is similar to the dicot root in many respects.
  It has epidermis, cortex, endodermis, pericycle, vascular bundles and pith. As
  compared to the dicot root which have fewer xylem bundles

Dicotyledonous Stem

• Epidermis: is covered with a thin layer of cuticle and may have Trichomes and stomata.
• Cortex: The cortex is made up of the multiple layers of cells including hypodermis, middle layer of parenchyma cells and innermost layer called endodermis.
• Endodermis cells are rich in starch grains and are called the starch sheath. Pericycle is present on the inner side of endodermis. Layers of radially placed parenchyma between the vascular bundles are called medullary rays.
• A large number of vascular bundles are arranged in a ring. Each vascular bundle is conjoint, open. Protoxylem is endarch

Monocotyledonous Stem

• The hypodermis is made up of sclerenchyma. Vascular bundles are conjoint, closed and  scattered. Each vascular bundle is surrounded by a sclerenchymatous bundle sheath.
• Phloem parenchyma is absent. Water-containing cavities are present within the vascular bundles.

Dorsiventral (Dicotyledonous) Leaf

• The leaf lamina of a dorsiventral leaf has 3 parts:  epidermis, mesophyll and vascular system.
• The upper epidermis is called adaxial epidermis and lower one is called abaxial epidermis. More number of stomata are present on the abaxial epidermis.
• There are two types of cells in the mesophyll: palisade parenchyma and spongy parenchyma. The palisade parenchyma is placed adaxially.
• The spongy parenchyma is situated below the palisade parenchyma and extends to the lower epidermis. There are numerous large spaces and air cavities between the cells of spongy parenchyma.
•  Vascular bundles are surrounded by a layer of thick-walled bundle sheath cells.

Isobilateral (Monocotyledonous) Leaf

• Stomata are present on both the surfaces of an isobilateral leaf. The mesophyll is not differentiated into palisade and spongy parenchyma.
• Some adaxial epidermal cells in grasses are modified into large, empty cells called bulliform cells. When the bulliform cells absorb water, they become turgid. So the leaf surface is exposed. During water stress, when the bulliform cells become flaccid, the leaves curl inwards to minimize water loss.

SECONDARY GROWTH
The increase in girth of a plant body is called secondary growth. The tissues involved in secondary growth are: vascular cambium and cork cambium.
Vascular Cambium:
In case of young stem vascular cambium is present in patches as a single layer between the xylem and phloem. It forms a complete ring at a later stage.
Activity of the Cambial Ring:

• The cambial ring becomes active and begins to cut off new cells, both towards the inner and the outer sides.
• The cells which are cut off towards pith mature into secondary xylem. The  cells which are cut off towards periphery mature into secondary phloem.
• The cambium is more active on the inner side than on the outer. As a result, the amount of secondary xylem produced is more than secondary phloem. The primary and secondary phloems get gradually crushed due to the continued formation and accumulation of secondary xylem.
• At some places, the cambium forms a narrow band of parenchyma, which passes through the secondary xylem and the secondary phloem in the radial directions. These are the secondary medullary rays

Spring wood and autumn wood:

•  Cambium is very active during the spring season, but less active during the winters. Hence, during spring; a large number of xylem elements are formed having wider vessels. During winter, less xylem elements are formed having narrow vessels.
• The wood formed during summer is called spring wood. The wood formed during winter is called autumn wood.
•  The two kinds of wood appear as alternate concentric rings in transverse section of a trunk of a tree. These are called annual rings and provide information about age of the tree.

Heartwood and sapwood:

• In old trees, the greater part of secondary xylem is dark in colour, hard, and resistant to attacks by microorganisms and insect. This region is made of dead elements with highly lignified walls. This wood is called heartwood. The heartwood gives mechanical support but does not conduct water.
• The peripheral part of the secondary xylem is lightly coloured. This is known as sapwood. It helps in conduction of water and minerals.

Cork Cambium

• Mmeristematic tissue which develops in the cortex region is called cork cambium or phellogen.
• The phellogen cuts off cells on both sides. The outer cells differentiate to form cork or phellem while the inner cells differentiate into secondary cortex or phelloderm.
•  Phellogen, phellem and phelloderm are collectively called periderm.
• Due to activity of the cork cambium, pressure builds up on the remaining layers peripheral to phellogen. These layers gradually die and fall off.

Lenticels

• At certain regions, the phellogen cuts  off  closely  arranged parenchymatous cells on the outer side instead of cork cells. These parenchymatous cells soon rupture the epidermis, forming a lens-shaped openings called lenticels.
• Lenticels permit the exchange of gases between the outer atmosphere and the internal tissue of the stem.

Secondary Growth in Roots

• The vascular cambium of the dicot root originates from the tissue located just below the phloem bundles. A portion of pericycle tissue present above the protoxylem forms a continuous wavy ring. It gradually becomes circular. Rest of the steps are similar as in dicot stem.
• Secondary growth takes place in stems and roots of gymnosperms. No secondary growth occurs in monocots.

Class 11 Biology Revision Notes for Morphology of Flowering Plants of Chapter 5

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Morphology is the branch of biological science that deals with the study of form, size, colour, structure and relative position of various parts of organisms.
Importance of morphology-

1. Knowledge of morphology is essential for recognition or identification of plants.
2. It gives information about the range of variations found in species.
3. Deficiency and toxicity symptoms are morphological changes that occur in response to shortage or excess of minerals.

Parts of Flowering Plants–

• All the flowering plants have roots, stem, leaves, flower and fruits. The underground parts of flowering plant are the root system and the portion above the ground forms the shoot system.

The Root

• In Dicotyledons, elongation of radicle forms the primary roots which bears lateral roots of several orders called secondary roots, tertiary roots, etc.
  Primary roots along with lateral roots forms the Tap root system. Example: Mustard, Gram, etc.
• In monocotyledons, primary root is replaced by large number of roots at its base of stem to constitute the Fibrous root system. Wheat, rice etc.
• The roots that arise from other parts of plant beside radicle are called adventitious roots. Example- Grass, Banyan tree, Maize, etc.
• The main function of root system are absorption of water and minerals from soil, providing proper anchorage to the plant parts and storing reserve food materials.

Regions of Roots–

• The apex of root is covered by a thimble like structure called root cap, it protect the tender apex of root while making way through soil.
• Above the root cap is region of meristematic activity having small cells with dense cytoplasm.
• The part above the region of meristematic activity is region of elongation where cells under go elongation and enlargement to increase the length of root.
• Region of maturation contain root hairs that help in absorption of water and minerals.

Modification of roots- Roots are modified for storage, nitrogen fixation, aeration and support.

• Tap root of carrot, turnip and adventitious root of sweet potato get swollen to store food.
• Prop root of Banyan and Stilt root of maize and sugarcane have supporting root coming out from lower node of stems.
• In Rhizophora, Pneumatophores help to get oxygen for respiration as it grows in swampy areas.

The Stem

• It is the ascending part of axis bearing branches, leaves, flowers and fruits. It develops from Plumule of the embryo.
• Stem bears nodes and internodes. The region of stem where leaves are born are called nodes and portion between two nodes are called internodes.
• The main function of stem is spreading branches, bearing leaves, flowers and fruits. It also conducts water and minerals from root to leaves and product of photosynthesis.
• Some stem perform special functions like storage of food, support, protection and vegetative propagation.

Modification of stems–

• Underground stem of potato, ginger and turmeric are modified to store food. They also act as organ of perennation in unfavorable conditions.
• Stem tendril help plants to climb as in cucumber, pumpkins, and grapes.
• Axillary buds of stem may modify into woody, straight and pointed thorns as in Citrus and Bougainvillea.
• Plants of arid regions modify their stem to flattened (Opuntia), fleshy cylindrical (Euphorbia) having chlorophyll for photosynthesis.

The Leaf

• Leaf is a green, dissimilar exogenous lateral flattened outgrowth which is borne on the node of a stem or its branches is specialized to perform photosynthesis.

• Leaves originate from shoot apical meristem and are arranged in an acropetal order.
• A typical leaf consists of three parts- Leaf base, Petiole, Lamina. Leaf is attached with stem by Leaf Base which may bear two small leaf like structure called stipule.
• Middle prominent vein is called mid vein. Veins provide rigidity to the leaf blade and act as channel for transport of water and minerals.
• The arrangement of vein and veinlets in the lamina is called venation.

Reticulate venation	Parallel venation
Veinlets form a network.Veins are irregularly distributed.It is present in all Dicotyledons like Gram, Pea, Beans and Mango etc.	A network is absent.Veins are parallel to one another.It is present in Monocotyledons like Grass, Banana, Rice, etc.

• A leaf having a single or undivided lamina is called Simple leaf. The incisions do not touch the mid rib. Example- Mango, Guava etc.
• When the incision of lamina reach up to the midrib and breaking it into a number of leaflets, it is called Compound leaves.
• In a Pinnately compound leaves, a number of leaflets are present on common axis called rachis. Example- Neem.
• In Palmately compound leaves, the leaflets are attached at common point. Example- Silk cotton.
• The pattern of arrangement of leaves on the stem or branch is called Phyllotaxy.
• In alternate type of phyllotaxy single leaf arise at each node as in China rose.
• In opposite types of phyllotaxy a pair of leaves arise from each node opposite to each other as in Guava.
• If more than two leaves arise at a node and form a whorl is called whorled type of phyllotaxy as in Alstonia.
• Leaves are modified to perform other functions like converted to tendril for climbing as in Peas and spines for defence in Cactus.

Inflorescence
The arrangement of flowers on the floral axis is termed as inflorescence. Two main types of inflorescence are racemose and cymose.

Racemose	Cymose
The main axis continuous to grow.Flowers are borne laterally in an acropetal succession.Example- Radish, Mustard.	Main axis terminates in flower having limited growth.Flowers are borne in a basipetal succession.Example- Jasmine, Bougainvillea.

The flower

• Flower is the reproductive part of angiospermic plants for sexual means of reproduction.
• A typical flower has four whorls arranged on a swollen end of stalk or pedicel called thalamus. They are Calyx, Corolla, Androecium and Gynoecium.
• When a flower has both androecium and gynoecium, the flower is called bisexual and flower having either androecium or gynoecium only is called unisexual.
• When flower can be divided into two equal radial halves in any radii passing through center the symmetry of flower is called actinomorphic (radial symmetry) as in Mustard, Datura, and Chili.
• When flower can be divided into two similar parts only in one vertical plane it is zygomorphic as in Pea, Gulmohar, Cassia etc.
• When Floral appendages are in multiple of 3,4 or 5 they are called trimerous, tetramerous and pentamerous respectively. Flower with bracts are called bracteates and without it ebracteate.
• Based on the position of ovary with respect to other floral part on thalamus, flowers are of following types:

1. Hypogynous flower– Ovary occupies the highest position. The ovary in such case is called superior. Eg. Mustard, brinjal and china rose.
2. Perigynous flowers-If the gynoecium is situated at the centre and other parts are on the rim at same height. Ovary is called half-inferior.
3. Epigynous flowers- The margin of thalamus grows to completely cover the ovary. Ovary is said to be inferior.

Calyx is the outermost whorl of the flower; its members are called sepals. They are generally green and leafy; protect the flower in bud stage. It may be gamosepalous (sepals united) or polysepalous (sepals free).
Corolla consists of petals, brightly coloured to attract the insects for pollination. They may be gamopetalous or polypetalous.

1. The mode of arrangement of sepals or petals in floral bud with respect to the other members of same whorl is called aestivation. In valvate, the whorls of sepals or petals touch each other as in Calotropis. In Twisted aestivation, the whorls overlap each other as in China rose.
2. In Imbricate aestivation, margin overlap each other but not in particular fashion as in Gulmohur.
3. In pea and bean flowers, there are five petals- the largest (standard) overlaps the two lateral petals (wings) which in turn overlap two smallest anterior petals (keel).  This type of aestivation is known as vexillary or papilionaceous.

The Androecium

• Androecium represent the male reproductive parts of flower, consists of stamens. Each stamen consists of filament and anther. Pollen grains are produced in pollen sac. Sterile stamen is called Stemenode.
• When stamens are attached with petals it is called epipetalous (Brinjal). Stamen may be free (polyandrous) or may be united in one bundle (monoadelphous), two bundles (diadelphous), more than two (polyadelphous).

The Gynoecium

• Female reproductive part of flower consists of one or more carpels. Each carpel is made up of stigma style and ovary.
• When more than one carpel is present, it may be free (apocarpous) as in lotus and rose or fused together (syncarpous) as in mustard and tomato.
• After fertilisation, ovules change into seeds and ovary mature into fruits.

Placentation

• The arrangement of ovules within the ovary is called placentation.

The fruit

• Mature and ripened ovary developed after fertilisation is fruit. If a fruit is formed without fertilisation of ovary it is called parthenocarpic fruit.
• Fruit consists of seeds and pericarp. Thick and fleshy pericarp is three layered called epicarp, mesocarp and endocarp.

• Dicotyledonous Seed is made up of a seed coat and an embryo. Embryo is made up of embryonal axis, radicle and cotyledons.
• Seed coat has two layers outer testa and inner tegmen. Hilum is scar through which seed is attached to the ovary. Small pore above the hilum is called micropyle.

Monocotyledonous seeds

• In monocotyledonous seed, outer covering of endosperm separate the embryo by a proteinous layer called aleurone layer.
• Single cotyledon is called as scutellum having a short axis bearing Plumule and radicle.
• Plumule and radicle are closed inside sheaths called as coleoptile and coleorhiza respectively.

SEMI -TECHNICAL DESCRIPTION OF A TYPICAL
FLOWERING PLANT
The plant is described beginning with its habit, vegetative characters – roots, stem and leaves and then floral characters inflorescence and flower parts.
The floral formula is represented by some symbols. In the floral formula, Br stands for bracteate K stands for calyx , C for corolla, P for perianth, A for androecium and G for Gynoecium. Fusion is indicated by enclosing the figure within bracket and adhesion by a line drawn above the symbols of the floral parts.
Family Fabaceae-

• This family was earlier known as Papilionoideae. Herbs, shrubs or tree root with root nodules. Pinnately compound leaves with reticulate venation.

Economic importance
Plants belonging to this family are sources of pulses like Gram, Arhar, Bean. Pea etc. and edible oils like groundnut, soybean, etc.
Family Solanaceae-

• Plant body herbs or shrubs, rarely small trees, commonly known as potato family. Leaves simple or pinnately compound. Reticulate venation.

Many of them are source of food (potato, tomato, Brinjal etc.), spices (Chilli) etc.
Family Liliaceae

• Commonly known as Lily family. Monocots, perennial herbs. Leaves alternate with parallel venation.
• Underground bulbs, corms or rhizomes.
• Flower bisexual, actinomorphic, sepals and petals are absent, having perianth.

It includes ornamental plants (Tulip), Medicine (aloe) and vegetable (colchicine).

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Class 11 Biology Revision Notes for Animal Kingdom of Chapter 4

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• Millions of species of animals have been described and it becomes more necessary to classify them to assign a systematic position.
• Animals are classified on the basis of arrangement of cells, body symmetry, nature of coelom, pattern of digestive, circulatory and reproductive system.

• Incomplete digestive system has one opening but complete digestive system has two opening- mouth and anus.
• Open circulatory system- blood is pumped out of heart and cells and tissue are directly bathed in it.
• Closed circulatory system- blood is circulated through arteries, veins and capillaries.

• The animals in which cells are arranged in two embryonic layer, external ectoderm and internal endoderm are called diploblastic. Eg. Porifera and Cnidaria.

• The animals in which developing embryo has a third germinal layer, mesoderm besides ectoderm and endoderm are called triploblastic. Eg. Platyhelminthes, Chordates.
• The body cavity which is lined by mesoderm is called coelom. Animals possessing coelom are called coelomate (Annelida, Chordates, Mollusca). In some animals cavity is not lined by mesoderm but scattered as pouches in between ectoderm and endoderm, are called pseudo-coelomates (Aschelminthes). The animals in which body cavity is absent are called acoelomate (Platyhelminthes).

• In some animals, body is externally and internally divided into segments with serial repetition as in earthworm, called metameric segmentation.

CLASSIFICATION OF ANIMALS
Phylum Porifera-

• Members of this phylum are commonly known as sponges. Mostly marine, asymmetrical and have cellular level of organization.
• They have water transport or canal system. Water enters through minute pores, Ostia into central cavity Spongocoel, from where it goes out through Osculum.
• Nutrition, respiration and excretion is performed by pathway of water transport system.
• Skeleton made up of spicules or spongin fibres.
• Egg and sperms are produced by same organism (hermaphrodite). Asexual reproduction by fragmentation and sexual reproduction by gametes formation.
• Fertilisation internal and development is indirect.
• Example– Sycon, Spongilla.

Phylum Cnidaria ( Coelenterate)-

• They are aquatic, mostly marine, sessile, free swimming, radially symmetrical animals.
• They exhibit tissue level of organization, diploblastic, coelomate with single opening.
• They show two types of body called polyp and medusa.
• Polyp is sessile, fixed, and cylindrical, without gonads. Example: Hydra, Adamsia. Medusa is free swimming, umbrella like having gonads like Aurelia and Jelly fish.
• Some cnidarians exhibits both forms (Obelia). Polyp produce medusa asexually and medusa produce polyp sexually.

Phylum Ctenophora-

• Commonly known as the Comb Jellies or Sea Walnuts.
• Exclusively marine, diploblastic, radially symmetrical, with tissue level of organization.
• Body bears eight ciliated comb plates which help in locomotion.
• Bioluminescence (to emit light) is present in Ctenophores.
• Are Hermaphrodite, fertilisation is external, development indirect.
• Example- Ctenoplana, Pleurobranchia.

Phylum Platyhelminthes (The Flat worms)

• Dorso-ventrally flattened body, bilaterally symmetrical, triploblastic, acoelomate with organs levels of organization.
• Hooks and sucker are present in parasitic forms. Flame cells help in osmoregulation and excretion.
• Fertilisation is internal, development is indirect. They are hermaphrodite.
• Example- Taenia, Planaria, Fasciola.

Phylum Aschelminthes (The Round Worm)

• They may be free-living, aquatic, terrestrial or parasitic in plants or animals.
• Bilaterally symmetrical, triploblastic, pseudo coelomate.
• Alimentary canal is complete with well-developed muscular pharynx.
• They are Dioecious. Females are longer than male.
• Example- Ascaris (round worm), Wucheriria(filarial worm), Ancyclostoma.

Phylum Annelida

• Aquatic or terrestrial, bilaterally symmetrical, segmented with organ system level of organization.
• Aquatic Annelids like Nereis possesses lateral appendages parapodia, for swimming. Nephridia help in osmoregulation and excretion.
• Neural system consists of paired ganglia connected by lateral nerves to a double ventral nerve cord.
• Dioecious (Nereis) or monocious (earthworm, leech)
• Example- Pheretima (earthworm), Hirunidaria (Blood sucking leech).

Phylum Arthropoda

• Largest phylum of animals which includes insects. They have organ system of organization. They are triploblastic, coelomate, bilaterally symmetrical with chitinous exoskeleton.
• Body consists of head, thorax and abdomen, jointed appendages (jointed feet). Respiratory organs are gills, book lungs or tracheal system with open circulatory system.
• Excretion through malpighian tubules, sense organs antenna or eyes. Fertilisation internal, mostly oviparous.
• Example-

Economically important – Apis (honey bee), Bombyx (silk worm).
Vectors – Anopheles, Ades, Culex (mosquito).
Living fossils – Limulus (king crab)
Phylum Mollusca

• Terrestrial or aquatic, organ level of organization, bilaterally symmetrical, triploblastic and coelomate.
• Body divided into head, muscular foot and visceral hump. Unsegmented and covered with calcareous shell.
• Feather like gills are present between hump and mantle.
• Mouth contains file like rasping organ for feeding called radula.
• Example- Pila, Octopus.

Phylum Echinodermata (The Spiny Skinned Animals)

• Endoskeleton of calcareous ossicles, marine with organ system of organization.
• Triploblastic, coelomate, presence of water vascular system help in locomotion, capture of food and respiration.
• Sexes are separate, fertilisation is external and development is indirect.
• Example- Asterias (Star fish), Cucumaria (Sea cucumber), Antedon (Sea lily).

Phylum Hemichordata

• Worm-like marine animals with organ system of organization, bilaterally symmetrical, triploblastic and coelomate animals.
• Body is cylindrical, composed of anterior proboscis, a collar and a long trunk.
• Open circulatory system, respiration by gills, excretory organ is proboscis glands.
• Sexes are separate, fertilisation external, indirect development.
• Example- Balanoglossus, Saccoglossus.

Phylum Chordates

• Presence of notochord, have dorsal hollow nerve chord and paired pharyngeal gill slits.
• Bilaterally symmetrical, triploblastic, coelomate with organs system levels of organization.
• Closed circulatory system, ventral heart, post-anal tail is present.

• In Urochordata, notochord is present only in larval tail. In Cephalochordate it extends from head to tail and persists throughout the life.
• Vertebrata possesses notochord in embryonic period which is replaced by vertebral column in the adults.
• Sub-phylum Vertebrata is further divided into two division Agnatha( lacks jaw) and Gnathostomata ( bears jaw).
• Gnathostomata is further divided into two super class- Pisces( bears fins) and Tetrapoda (bears limbs).

Class Cyclostomata (Circular mouthed fishes)–

• They are ectoparasites on some fishes. They have sucking and circular mouth without jaws.
• Body devoid of scales, gill slits for respiration, cranium and vertebral column is cartilaginous.
• Circulation is closed type. They are marine but migrate to fresh water for spawning and die after few days. Larva return to seas after metamorphosis.
• Example– Petromyzon (Lamprey), Maxine (Hag fish).

Class Chondrichthyes (The Cartilaginous Fish)

• They are marine, streamlined body, have cartilaginous endoskeleton, cold blooded, tough skin with minute placoid scales.
• Gill slits are separate without operculum.
• They have powerful jaw and are predators.
• Air bladder is absent, hence to avoid sinking swims constantly. Heart is two chambered, cold blooded (Poikilothermous).
• Sexes separate. Males have pelvic fins which bear claspers. Internal fertilisation, many are viviparous.
• Electric organ is present in Torpedo and Poison sting in Trygon

Example- Scoliodon (Dog fish), Carcharodron (great white shark).
Class Ostechthyes (The body fish)

• Marine and fresh water both have bony endoskeleton. Streamlined body with four pair of gills covered by operculum.
• Skin is covered with scales, air bladder is present, and heart is two chambered, cold blooded.
• Sexes are separate, fertilisation external, oviparous and development direct.

Example
Marine- Hippocampus (Sea horse), Exocoetus (Flying fish).
Fresh water- Labeo (Rohu), Catla ,Clarias (Magur).

Amphibia	Reptilia	Aves	Mammals
Can live in aquatic as well as terrestrial habitat.	Mostly terrestrial animals.	Presence of feathers for flying.	Mostly terrestrial, a few can fly and live in water.
Two pairs of limbs	Limb two pair if present.	Forelimb is modified into wings.	Two pair of limbs.
Moist skin without scales.	Dry and cornified skin having scale or scute.	Skin is dry without glands. Long bones are hollow with air cavities.	Skin possesses hairs. Mammary gland is present to produce milk.
Respiration by gills, lungs or skin.	Respiration by lungs.	Respiration by lungs.	Respiration by lungs.
Heart three chambered, cold blooded.	Heart three chambered, Crocodile 4-chambered .	Heart is four chambered, warm blooded.	Heart four chambered.
Oviparous	Oviparous	Oviparous	Viviparous or Oviparous.
Rana (frog), Salamander, Hyla	Chamelion, Crocodilus, Naja	Columba, Pavo, Ostrich.	Platypus(oviparous) Camel, Dog, Blue whale.

Class 11 Biology Revision Notes for Plant Kingdom of Chapter 3

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• Eukaryotic, multicellular, chlorophyll containing and having cell wall, are grouped under the kingdom Plantae. It is popularly known as plant kingdom.
• Phylogenetic system of classification based on evolutionary relationship is presently used for classifying plants.
• Numerical Taxonomy use computer by assigning code for each character and analyzing the features.
• Cytotaxonomy is based on cytological information like chromosome number, structure and behaviour.
• Chemotaxonomy uses chemical constituents of plants to resolve the confusion.

Algae: These include the simplest plants which possess undifferentiated or thallus like forms, reproductive organs single celled called gametangia. It includes only Algae.
Characteristic of Algae

• Plant body is thallus, which may be unicellular, colonial, filamentous or parenchymatous.
• Usually aquatic but a few are also found in moist terrestrial habitats like tree trunks, wet rocks, moist soil, etc.
• Vascular tissues and mechanical tissues are absent.
• Reproduction is vegetative by fragmentation, asexual by spore formation (zoospores) and sexual reproduction by fusion of two gametes which may be Isogamous (Spirogyra), Anisogamous (Chlamydomonous) or Oogamous (Volvox).
• Life cycle is various- haplontic, diplontic or diplohaplontic.

Green Algae	Brown Algae	Red Algae
Mostly fresh water and sub aerial.	Mostly marine.	Mostly marine.
Unicellular organisms abundant.	Unicellular species are absent.	Unicellular species fewer.
Chlorophyll a and b type.	Chlorophyll a and c type.	Chlorophyll a and d type.
Reserve food is starch	Reserve food is laminarin.	Reserve food is floridean starch.
Cell wall is of cellulose.	Cell wall contains cellulose and algin.	Cell wall contains cellulose and poly-sulphate esters.
Fucoxanthin is absent	Fucoxanthin present.	Phycoerythrine is present.
Zoospores present.	Zoospores present.	Zoospores absent.
Chlamydomonas, Ulothrix, spirogyra.	Focus, Sargassum, ectocarpus.	Polysiphonia, Gelidium, Porphyra etc.

Economic importance-

1. A number of brown algae ( Laminaria, Sargassum) are used as food in some countries.
2. Fucus and Laminaria are rich source of Iodine.
3. Laminaria and Ascophyllum have antibiotic properties.
4. Alginic acid is obtained from Fucus and Sargassum, which is used as emulsions.

Bryophytes – They are non-vascular mosses and liverworts that grow in moist shady region. They are called amphibians of plants kingdom because these plants live on soil but dependent on water for sexual reproduction.
Characteristic features-

• Live in damp and shady habitats, found to grow during rainy season on damp soil, rocks, walls, etc.
• The dominant phase or plant body is free living gametophyte.
• Roots are absent but contain rhizoids
• Vegetative reproduction is by fragmentation, tubers, gemmae, buds etc. sex organs are multicellular and jacketed. The male sex organ is called antheridium. They produce biflagellate antherozoids. The female sex organ called archegonium is flask-shaped and produces a single egg.
• Sporophyte is dependent on gametophyte for nourishment.

Bryophytes Hepaticopsida (Liverworts)

• The plant body of a liverwort is thalloid, e.g., Marchantia. The thallus is dorsiventral and closely appressed to the substrate.
• Asexual reproduction in liverworts takes place by fragmentation, or by the formation of specialised structures called gemmae.
• Gemmae are green, multicellular, asexual buds, which develops in small receptacles called gemma cups. The gemmae becomes detached from the parent body and germinate to form new individuals
• During sexual reproduction, male and female sex organs are produced either on the same or on different thalli. The sporophyte is differentiated into a foot, seta and capsule. Spores produced within the capsule germinate to form
  free-living gametophytes.

Bryopsida (Mosses)

• The gametophyte of mosses consists of two stages- the first stage is protonema stage, which develops directly from spores. It is creeping, green and frequently filamentous. The second stage is the leafy stage, which develops from secondary protonema as lateral bud having upright, slender axes bearing spirally arranged leaves.
• Vegetative reproduction is by the fragmentation and budding in secondary protonema. In sexual reproduction, the sex organs antheridia and archegonia are produced at the apex of the leafy shoots.
• Sporophytes in mosses are more developed and consist of foot, seta and capsule.
• Common examples are Funaria, Polytrichum, Sphagnum etc.

Pteridophytes

• They are seedless vascular plants that have sporophytic plant body and inconspicuous gametophyte. Sporophytic plant body is differentiated into true stem, roots and leaves.
• Vascular tissue are present but vessels are absent from xylem and companion cells and sieve tube are absent.
• Sporophytes bear sporangia that are subtend by leaf like appendages called sporophylls. In some plants (Selaginella) compact structure called strobili or cone is formed.
• Sporangia produce spores by meiosis in spore mother cells. Spores germinate to produce multicellular thalloid, prothallus.
• Gametophyte bears male and female sex organ called antheridia and archegonia. Water is required for fertilisation of male and female gametes.
• Most of Pteridophytes produce spores of similar kind (homosporous) but in Selginella and Salvinia, spores are of two kinds (heterosporous) larger called megaspore that produce female gametophyte and smaller microspore that produce male gametes.

Gymnosperms:

• Gymnosperms are those plants in which the ovules are not enclosed inside the ovary wall and remain exposed before and after fertilisation.
• They are perennial and woody, forming either bushes or trees. Some are very large (Sequoia sempervirens) and others are very small (Zamia pygmia).
• Stem may be unbranched(Cycas) or branched(Pinus). Root is taproot. Leaves may be simple or compound.
• They are heterosporous, produce haploid microspore and megaspore in male and female Strobili respectively.
• Male and female gametophytes do not have independent free-living existence. Pollination occurs through air and zygote develops into embryo and ovules into seeds. These seeds are naked.
• Example- Pines, Cycus, Cedrus, Ginkgo, etc.

Angiosperms

• Pollen grain and ovules are developed in specialized structure called flower. Seeds are enclosed inside the fruits.
• Size varies from almost microscopic Wolfia (0.1cm)to tall tree Eucalyptus (more than 100m
• The male sex organs in a flower is the stamen. It contains pollen grain.
• The female sex organs in a flower is the pistil or the carpel. Pistil consists of an ovary enclosing one or many ovules. Within ovules are present highly reduced female gametophytes termed embryo-sacs.
• Each embryo-sac has a three-celled egg apparatus – one egg cell and two synergids, three antipodal cells and two polar nuclei. The polar nuclei eventually fuse to produce a diploid secondary nucleus.

Angiosperms are further classified into:

• Monocotyledons
• Dicotyledons

Monocotyledons	Dicotyledons
Single cotyledons.Parallel venation.Fibrous root system.Closed vascular bundle.More number of vascular bundles.Banana, wheat, rice.	Two cotyledons.Reticulate venation.Tap root system.Open vascular bundle.Less number of vascular bundles.Gram, mango, apple.

• Double fertilisation- Each pollen grain produce two male gametes. One gametes fuse with egg to form embryo. This is called Syngamy. Other gametes fuse with two polar nuclei to form endosperm, triple fusion. Since fertilisation takes place twice, it is called double fertilisation.

Alternation of generation
Different plant groups complete their life cycles in different patterns. Angiosperms complete their life cycle in two phases- a diploid sporophytes and haploid gametophyte. The two follows each other. This phenomenon is called alternation of generation.

1. Haplontic- Saprophytic generation is represented by only the one-celled zygote. Meiosis in zygote results into haploid spores to form gametophytes, which is the dominant vegetative phase. Example- Volvox, Spirogyra etc.

1. Diplontic- Diploid sporophytes is dominant, independent, photosynthetic plants. The gametophyte is represented by single to few celled. All seed bearing plants fall under this category.

1. Haplo-diplontic- Both phases are multicellular and intermediate condition is present. It is present in Bryophytes and Pteridophytes.

Revision Notes for Class 11 Biology Chapter 2 – Biological Classification

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Biological classification is the scientific procedure of arranging organisms into groups and subgroups on the basis of their similarities and dissimilarities and placing the group in a hierarchy of categories.
Importance of classification-

• It is not possible to study every organism. Study of one or two organism of a group gives sufficient information about the essential features of the group.
• It helps in identification of new organism.
• Classification helps in knowing the relationship amongst different groups of organisms.
• The organism of past cannot be studied without a proper system of classification.

Classification

• Artificial system of classification
• Natural system of classification
• Phylogenetic system of classification

Artificial system of classification– Only one or two morphological characters for grouping of organism is used. Flowering and non-flowering plants, enaima and anaima. Aristotle classification.
Natural system of classification– Takes into consideration comparable study of a number of characters so as to bring out natural similarities and dissimilarities and hence natural relationships among the organisms. Bentham and Hooker classification, etc.
Phylogenetic System of Classification– Based on the evolutionary relationship of organisms. In this system organism are classified on the basis of their evolution on earth from primitive to highly evolved. Engler and Prantl classification and Hutchinson classification, etc.

• Two kingdom : Plantae Animalia
• Three kingdom : Plantae Protista Animalia
• Five kingdom : Monera Protista Fungi Plantae Animaila
• In two kingdom system of classification organisms are grouped on the basis of presence and absence of cell wall as proposed by Linnaeus( father of taxonomy).
• Three kingdom systems- Haeckel separated unicellular animals, algae and fungi on the basis of lack of tissue differentiation and new kingdom Protista was introduced.
• Five kingdom systems- R.H.Whittaker divided all the organism into five kingdom in order to develop phylogenetic classification.

1. Monera– The kingdom includes all prokaryotes- mycoplasma, bacteria, actinomycetes and cyanobacteria.

1. Unicellular, prokaryotes and contain the most primitive of living forms
2. The cells are microscopic and cell wall is generally present.
3. Genetic materials are not organized into nucleus and contain naked DNA.
4. Membrane bounded organelles are absent.
5. Reproduction is asexual except gene recombination.
6. Flagella may be present and are of single stranded.

Example- Blue-green algae, Bacteria, etc.
Bacteria are the most abundant micro-organism that can survive in all kinds of climate.

• They are group of most primitive prokaryotes which live under most hostile conditions like extreme salty area (halophiles), hot springs (thermoacidophiles) and marshy area (methanogens). They differ from other bacteria in having different cell wall structure (absence of peptidoglycan). Methanogens are present in the gut of several ruminant animals like cows and buffalo, which is responsible for production of biogas (methane) from dung of these animals.

Eubacteria – They are called as true bacteria. They contain rigid cell wall, if motile contain flagellum. Cyanobacteria or blue-green algae are gram positive photosynthetic bacteria. They contain chlorophyll a and carotenoids. They may be unicellular, colonial or filamentous, fresh water, marine or terrestrial. Some of them have specialized heterocyst cells to perform nitrogen fixation (Nostoc and Anabaena).
Chemosynthetic bacteria oxidize inorganic substances like nitrate, nitrite, ammonia etc. to produce energy and help in recycling of nitrogen, phosphorous, sulphur etc.
Heterotrophic bacteria are most abundant and act as decomposer. They are helpful in production of curd, antibiotic and fixing nitrogen in leguminous plants. Some of them are pathogenic and cause disease like cholera, typhoid, tetanus and citrus canker.

Mycoplasma – they are the simplest free living prokaryotes. They are also known as PPLO (Pleuropneumonia like organism). They lack cell wall and can survive without oxygen. They cause disease in plants and animals.
Protista– Kingdom Protista includes Chrysophytes, Dinoflagellates, Eugleoids, slime mould and Protozoans.

1. It includes all unicellular and colonial eukaryotes.
2. Most of them are aquatic forming plankton.
3. Mode of nutrition may be photosynthetic, saprophytic, parasitic or holozoic.
4. Flagella if present are 11 stranded with 9+2 arrangement of microtubules composed of tubulin.
5. Genetic material consists of 2 or more DNA molecules.

• They includes diatoms and golden algae (desmids) found in fresh water as well as marine water.
• In diatoms cell wall forms two thin overlapping cells which fit together as in soap box.
• The siliceous indestructible cell wall pile up at the bottom of water reservoirs and form big heaps called diatomaceous earth. It may extend for hundred meter and used for polishing, filtration of oil and syrups. They are chief producer in oceans.
• They are basically unicellular, motile, biflagellate and photosynthetic protists.
• Predominate colour is golden brown but yellow, green, red and even blue also exists.
• Some Dinoflagellates like Gymnodinium and Gonyaulax grow in large number in the sea and make the water look red and cause the so called “red tide”.
• They are Euglena like unicellular flagellates which possess pellicle instead of cell wall which make their body flexible.
• They have two flagella, one short and other long.
• They are photosynthetic in presence of sunlight and act as predators in absence of sunlight.
• Example- Euglena, Peranema.

Slime Moulds

• They are saprophytic protists and feeds on decaying twigs and leaves.
• Under favorable condition, they form an aggregation called plasmodium which produce fruiting bodies bearing spores.
• The cell wall of spores contain cellulose.
• The spores are dispersed by air currents.
• Example- Physarum, Fuligo.

Protozoans

• All protozoans are heterotrophs and live as predators or parasites.
• They are considered as primitive relatives of animals.
• Amoeboids move and capture food by pseudopodia. Some are parasitic also.
• Flagellated protozoans are free-living or parasitic. They have flagella.
• Ciliated protozoans are aquatic and have cilia all over the body for movement.
• Sporozoans includes organism that have infectious spore like stage in their life cycle.

Kingdom Fungi–

• They are achlorophyllous, heterotrophic, spore forming, non-vesicular eukaryotic organisms.
• Cell wall is made up of chitin or fungal cellulose.
• Reserved food is glycogen.
• Mode of nutrition is saprophytic, parasitic or symbiotic.
• Reproduction may be vegetative (fragmentation, fission or budding), asexual (conidia, sporangiospores or zoospores) or sexual reproduction by oospores, ascospore and basidiospores.
• Sexual cycles involves the following steps-

1. Plasmogamy, fusion of male and female gametes.
2. Karyogamy, fusion of two nuclei.
3. Meiosis in zygote to produce haploid spores.

Phycomycetes–

• They are found in aquatic habitat and on decaying wood in moist and damp places.
• The mycelium is aseptate and coenocytic.
• Asexual reproduction by zoospores( motile) or aplanospores (non-motile).
• Example- Mucus, Rhizopus, Albugo etc.

Ascomycetes (The sac fungi)

• They are saprophytic, decomposers, parasitic or coprophilous (growing on dung).
• Mycelium and branched and septate and asexual spores are conidia.
• Sexual spores are called ascospores produced inside the fruiting body called ascocarps.

Example- Neurospora, Asperigillus, Claviceps etc.
Basidiomycetes (The club fungi)

• The mycelium is branched and septate.
• Vegetative reproduction is by fragmentation. Asexual spores are not found. Sexual reproduction is by two vegetative or somatic cells forming basidium.
• Basidiospores are produced in basidium by developing a fruiting body called basidiocarps.
• Example- Agaricus, Ustilago, Puccinia.

Deuteromycetes (The fungi imperfect)

• Only vegetative and asexual phase is known.
• Mycelium is septate and branched. Some members are saprophytes or parsites.
• Example- Alternaria, Trichoderma, Colletotrichu.

Kingdom Plantae

1. Eukaryotic, chlorophyll bearing organism.
2. Life cycle is divided into diploid saprophytic and haploid gametophytic, which alternate with each other.
3. Kingdom Plantae includes Algae, Bryophytes, Pteridophytes, Gymnosperms and Angiosperms.

Kingdom Animalia

1. Heterotrophic, eukaryotic organisms that are multicellular and cell wall is absent in the cell.
2. Mode of nutrition is holozoic and reserve food is glycogen or fats.
3. Sexual reproduction is by copulation between male and female followed by embryological development.

Virus, Viroids and Lichens
Five kingdom system of classification do not includes Virus, Viroids and Lichens.

• Viruses are non-cellular organisms having inert crystalline structure outside the living. When they enter the living cell, they take over the machinery of living cell to replicate themselves.
• D.J.Ivanowsky recognized certain microbes as causal organism of mosaic disease of tobacco.
• In addition to proteins, viruses also contain genetic material that could be DNA or RNA. In general, virus that infect plants have single stranded RNA and virus that infect animals have double stranded DNA.
• Some common diseases caused by virus are common cold, influenza, AIDS, small pox, leaf rolling and curling.
• Bacteria feeding virus are called Bacteriophage.They are usually double stranded DNA viruses.
• The protein coat called capsid is made of small subunits called capsomeres, protects the nucleic acid. These capsomeres are arranged in helical or polyhedral geometric forms.
• Viroids are discovered by T.O.Diener as new infectious agent smaller than virus causing potato spindle tuber disease. They are free RNA without protein coat.

Lichens are symbiotic association between algae and fungi. The algal part is called Phycobiont and fungal parts are called Mycobiont. They are good pollution indicator as they do not grow in polluted area.