CBSE Notes

By going through these CBSE Class 11 Biology Notes Chapter 6 Anatomy of Flowering Plants, students can recall all the concepts quickly.

Anatomy of Flowering Plants Notes Class 11 Biology Chapter 6

→ Anatomically, a plant is made up of different kinds of tissues. Tissue is broadly classified into meristematic (apical, lateral, and intercalary) and permanent (simple and complex) tissues.

→ Tissues perform various functions such as assimilation, mechanical support, storage, and transportation of materials such as water, minerals, and photosynthates.

→ There are three types of tissue systems viz. epidermal ground and vascular.

→ The ground tissue system may be divided into three zones-cortex, pericycle, and pith.

→ The vascular or conducting tissue system includes the xylem and phloem.

→ Dicotyledonous and monocotyledons plants show marked variation in internal structures. They differ in the type, number, and location of vascular bundles.

→ Secondary growth occurs in most of the dicotyledonous roots and stems and it increases the diameter of the plant.

→ The wood is actually secondary xylem, which is formed during one growth session. There are different types of wood on the basis of their composition.

→ Meristems: Growth in plants is largely restricted to specialized regions of active cell division called meristems.

→ Apical meristems: The meristem which occurs at the tips of roots and shoots and produces primary tissues are called apical meristems.

→ Intercalary meristems: The meristem which occurs between mature tissues is known as the intercalary meristem

→ Primary meristem: Both apical meristems and intercalary meristem are also called the primary meristem.

→ Lateral meristem: The meristem that occurs in the mature regions of shoots and roots of many plants, particularly those that produce a woody axis and appear later than primary meristem is called the lateral meristem

→ Protoxylem: Primary xylem is of two types. The first formed xylem elements are called protoxylem.

→ Metaxylem: The later formed xylem is called metaxylem.

→ Endarch: In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery of the organ, called Endarch.

→ Cuticle: The outside of the epidermis is often covered with a waxy thick layer which is called the cuticle.

→ Guard cells: Each stoma is composed of two bean-shaped cells known as the guard cells.

→ Subsidiary cells: Sometimes, a few epidermal cells, in the vicinity of the guard cells become specialized in their shape and size, known as subsidiary cells.

→ Stomatal apparatus: The stomatal aperture, guard cells, and the surrounding subsidiary accessory cells are together called stomatal apparatus.

→ Trichomes: The cells of the epidermis bear a number of hairs known as trichomes.

→ Mesophyll: In leaves, the ground tissues consists of thin-walled chlorenchyma and is called mesophyll.

→ Open vascular bundles: The xylem and phloem together constitute vascular bundles. Such vascular bundles are called open vascular bundles.

→ Radial: When xylem and phloem within a vascular bundle are arranged in an alternate manner on different radii as in the roots are called radial as in the roots.

→ Epidermis: The outermost layer is the epidermis.

→ Endodermis: The innermost layer of the cortex is called the endodermis.

→ Conjunctive tissue: The parenchymatous cells which lie between the xylem and phloem are called conjunctive tissue.

→ Mesophyll: The tissue between the upper and the lower epidermis is called the mesophyll

→ Bulliform cells: In grasses, certain adaxial epidermal cells along the veins modify themselves into large, empty, colourless cells, which are called bulliform cells.

→ Secondary growth: Apart from primary growth most dicotyledonous plants exhibit an increase in girth. This increase is called secondary growth.

→ Springwood or earlywood: The wood formed during this season is called springwood pr earlywood.

→ Autumn wood or latewood: In winter, the cambium is less active and forms xylary elements. These have narrow vessels, and this wood is called autumn wood or latewood.

→ Annual ring: The two kinds of woods appear as alternate concentric rings, constituting an annual ring.

→ Cork cambium: Sooner or later, another meristematic tissue called cork cambium or phellogen.

→ Periderm: Phellogen, phellem, and phelloderm are collectively known as periderm.

By going through these CBSE Class 11 Biology Notes Chapter 5 Morphology of Flowering Plants, students can recall all the concepts quickly.

Morphology of Flowering Plants Notes Class 11 Biology Chapter 5

→ The . flowering plants exhibit enormous variation in the shape, size and structure, mode of nutrition, life span, habit, and habitat.

→ Plants are differentiated into root, stem, and leaves with flowers and fruits of various types.

→ The roots system absorbs water and minerals from the soil and anchors the plants.

→ Stems are generally negatively geotropic and aerial.

→ Leaves are the main photosynthetic organs of the plant. The outline of the leaf-blade margin and tip shows an enormous variation. There are structural modifications of root, stem, and leaves depending upon various functions.

→ The flower is a modified shoot meant for sexual reproduction.

→ The flowers are arranged in different types of inflorescence. After fertilization, the ovary is converted into fruits and ovules into seeds.

→ Seeds either may be monocotyledons or dicotyledons. On the basis of their development fruits may be of different types.

→ A flowering plant is described in definite sequence by using scientific terms.

→ Scientific description of a few selected plant families including their economic importance has been given as a sample for the study.

→ Root system: The root system normally lies underground and consists of the main root and its branches.

→ Shoot system: The shoot system is normally aerial and consists of the main stem, lateral branches, and leaves.

→ Taproot system: The taproot and its branches together constitute a tap root system.

→ Primary root: The first root is generally formed by the elongation of the radicle and is called the primary root.

→ Secondary roots: It continues growing and produces lateral roots called secondary roots.

→ Adventitious root system: Roots that develop from any part of a plant other than the radicle or its branches are called adventitious root systems.

→ Modifications of root: Modifications are the morphological changes in an organ to perform certain special functions other than or in addition to the normal functions.

→ Buds: A bud is a compacted under developed shoot having a growing point, surrounded by closely placed immature leaves.

→ Runners: They are sub-aerial weak, slender lateral branches, that grow horizontally along the soil surface.

→ Offsets: They are one internode long, stout, slender, and condensed runner found in rosette plants at the ground or water level.

→ Adaptation: Adjustment of an organism to its environment.

→ Gynomonoecious: A plant having female and intersexual flowers e.g. sunflower.

→ Haustorium: A projection that acts as a penetrating and absorbing organ.

→ Radicle: Portion of the plant embryo that develops into the primary root.

→ Transpiration: The giving off water vapor from the surface of the leaf.

By going through these CBSE Class 11 Biology Notes Chapter 4 Animal Kingdom, students can recall all the concepts quickly.

Animal Kingdom Notes Class 11 Biology Chapter 4

→ The animal kingdom is the most diverse group of organisms, which include about 1.2 million living species. Animals are heterotrophic organisms, which ingest food. Most animals move about in search of food. Some are sedentary or remain fixed at a place. In the food enters in their body by the water current. These two methods of feeding, shape the anatomy and behavior of animals to a great extent.

→ The major aim of classification is to express the relationship existing between different organisms. Based on certain characteristics, organisms are grouped together and separated from unrelated ones.

→ Over a million species of animals have already been described and many more are yet to be discovered. Basic fundamental features such as levels of the organization, symmetry, cell organization, body cavity and coelom, segmentation, etc., have enabled us to broadly classify the animal kingdom to a certain extent. Besides the fundamental features, there are many other distinctive characters, which are specific for each phylum or Class.

→ Porifera includes multicellular animals which exhibit a cellular level of organization and have characteristic flagellated collar cells (Choano- cytes). The cnidarians have tentacles and bear cnidoblasts. They are mostly aquatic, being sessile or free-floating. The ctenophores are marine animals with comb plates.

The platyhelminths have a flat body and exhibit bilateral symmetry. The parasitic forms show distinct suckers and hooks. Aschelminthes include parasitic as well as non-parasitic roundworms.

→ The annelids are metamerically segmented animals with a true coelom. The mollusks have a soft body surrounded by an external calcareous shell. The arthropods are the most successful group of animals characterized by the presence of jointed appendages.

The body is covered with an external skeleton made of chitin. The echinoderms possess spiny skin. Their most distinctive feature is the presence of a water vascular system. The hemichordates are a small group of worm-like marine animals. They have a cylindrical body with proboscis, collar, and trunk. This phylum was earlier considered as a subphylum under the phylum Chordata.

→ The phylum, Chordata, includes animals, which possess a notochord either throughout or during early embryonic life. Other common features observed in the chordates are the dorsal, hollow nerve cord and the paired pharyngeal gill-slits. Some of the vertebrates do not possess jaws (Agnatha) whereas most of them possess jaws (Gnathostomata). Agnatha is represented by the class Cyclostomata. They are the most primitive chordates and are ectoparasites on fishes. Gnathostomata has two superclasses Pisces and Tetrapoda.

→ Classes Chondrichthyes and Osteichthyes bear fins for locomotion and are grouped under Pisces. The Chondrichthyes are fishing with cartilaginous endoskeleton and are mostly marine. Whereas, classes Amphibia, Reptilia, Aves, and Mammalia, move with the help of two pairs of limbs and are thus grouped under Tetrapoda.

→ The amphibians are adapted to live both on land and water. Reptiles are characterized by the presence of dry and cornified skin. Limbs are absent in snakes. Fishes, amphibians, and reptiles are poikilothermous (cold¬blooded).

→ Aves, commonly known as birds, are warm-blooded animals with forelimbs modified into wings for flying and hind limbs adapted for walking, swimming, perching, or clasping.

→ The unique features of mammals are the presence of mammary glands and hairs on the skin. They exhibit viviparity. Mammals are the most intelligent among all the animals.

→ Radial Symmetry: When any plane passing through the central axis of the body divides the organism into halves that are approxi¬mately mirror images, it is called radial symmetry.

→ Bilateral symmetry: Animals like annelids, arthropods, etc., where the body can be divided into identical left and right halves in only one plane, exhibit bilateral symmetry.

→ Diploblastic: Animals, in which the cells are arranged into two embryonic layers, external ectoderm and internal endoderm, are called diploblastic

→ Triploblastic: Those animals in which the developing embryo has a third germinal layer, mesoderm, in between the ectoderm and endoderm are called triploblastic animals.

→ Coelom: The body cavity, which is lined by mesoderm is called coelom.

→ Eucoelomates: Animals possessing coelom are called coelomates.

→ Pseudocoelomates: Such a body cavity is called pseudocolor and the animals possessing them are called pseudocoelomates.

→ Metamerism: In some animals, the body has many segments, which show serial repetition of the phenomenon is known as metamerism.

→ Polyp and medusa: Cnidarians exhibit two basic body forms called Polyp and Medusa.

→ Flatworms: Platyhelminthes are Dorso ventrally flattened and, hence, commonly known as flatworms.

→ Brain ganglion: Hooks and suckers are present in the parasitic forms. They possess a concentration of nervous tissue in the head called the brain ganglion.

→ Flame cells: Specialized cells called flame cells help in osmo¬regulation and excretion.

→ Radula: Mollusca mouth contains file-like rasping organs for feeding, called a radula.

→ Metamorphosis: The process of transformation of a larva into an adult is called metamorphosis.

→ Cloaca: Alimentary canal, urinary, and reproductive tracts open into a common chamber called the cloaca, which opens to the exterior through an aperture called the cloacal aperture.

By going through these CBSE Class 11 Biology Notes Chapter 3 Plant Kingdom, students can recall all the concepts quickly.

Plant Kingdom Notes Class 11 Biology Chapter 3

→ Plant kingdom includes algae, bryophytes, pteridophytes gymnosperms, and angiosperms.

→ Algae are chlorophyll-bearing simple, thalloid, autotrophic, and largely aquatic organisms. Depending on the type of pigment possessed and the type of stored food, algae are classified into three classes, namely Chlorophyceae, Phaeophyceae, and Rhodophyceae.

→ Bryophytes are plants that can live on soil but are dependent on water for sexual reproduction. Their plant body is more differentiated than that of algae. It is thallus-like and prostrate or erect, attached to the substratum by rhizoids. They possess root-like, leaf-like, and stem-like structures.

→ The bryophytes are divided into liverworts and mosses.

→ In pteridophytes, the main plant is a sporophyte that is differentiated into true root, stem, and leaves. These organs possess well-differentiated vascular tissues.

→ The gymnosperms are the plants in which ovules are not enclosed by any ovary wall. After fertilization, the seeds remain exposed and therefore these plants are called naked seeded plants.

→ The gymnosperms produce microspores and megaspores which are produced in microsporophylls and megasporophylls- are arranged spirally on axis to form male and female cone respectively.

→ In angiosperms the male sex organs (stamen) and female sex organs (pistil are borne in a flower. Each stamen consists of a filament and an anther. The anther produces pollen grains (male gametophyte) after meiosis.

→ The pistol consists of an ovary enclosing one to many ovules. Within, the ovule is. the female gametophyte or embryo sac which contains the egg cell.

→ The pollen tube enters the embryo sac where two male gametes are discharged. One male gamete fuses with egg cell (syngamy) and the other fuses with diploid secondary nucleus (triple fusion).

→ However different plant groups, as well as individuals, may show different patterns of life cycle haplontic, diplontic er intermediate.

Table 3.1 Divisions of algae and their main characteristics:

→ Phylogenetic classification System: A system based on evolutionary relationships between the various organisms.

→ Antheridium: Male sex organ in bryophytes.

→ Archegonium: Female sex orgen in bryophtes.

→ Homosporous: Ptendophytes plants having similar kinds of spores.

→ Heterosporous: Plants that produce two kinds of spores, macro, and microspores.

By going through these CBSE Class 11 Biology Notes Chapter 2 Biological Classification, students can recall all the concepts quickly.

Biological Classification Notes Class 11 Biology Chapter 2

Aristotle was the first to propose the biological classification of plants and animals on the basis of simple morphological characters.

Later on, Linnaeus classified all living organisms into two kingdoms:

1. Plantae and
2. Animalia.

An elaborate five kingdom classification was proposed by Whittaker.

These include Monera, Protista, Fungi, Plantae, and Animalia
1. Kingdom Monera includes all types of bacteria etc. These organisms show the most extensive metabolic, diversity. In the mode of nutrition, they may be autotrophic or heterotrophic.

2. Kingdom Protista includes all single-celled eukaryotes. These include Chrysophytes, Dinoflagellates, Eaglenoids, Slime-moulds, and Protozoans. They reproduce both sexually and asexually and have defined nucleus and other membrane-bound organelles.

3. Kingdom Fungi show a great diversity in structures and habitat. They reproduce both sexually and asexually. Most Fungi are saprophytic.

4. Plantae includes all eukaryotic chlorophyll-containing organisms. The life cycle of plants exhibit alternation of generations-gametophytic and sporophytic generations.

5. Kingdom Animalia includes heterotrophic eukaryotic, multicellular organisms lacking a cell wall. They’ll reproduce by sexual mode

→ Saprophytes Organisms that absorb organic matter from dead substrates are called saprophytes.

→ Parasites Organisms that depend on living plants and animals are called parasites.

→ Plasmogamy The fusion of protoplasms between two motile or non-motile gametes.

→ Karyogamy The fusion of two nuclei.

→ Alternation of generation The lengths of the haploid and diploid phases and whether these phases are free-living or dependent on others. Such a phenomenon is called alternation of generation.

→ Viroids Micro-organisms smaller than viruses that lack the protein coat are termed viroids.