Diversity in living organisms class 9 Notes:

Diversity:

Diversity is the occurrence of different varieties or forms. The term biodiversity refers to the number and types of organisms present on earth.

About 1.7-1.8 million species have been identified and described but scientists have estimated that there are around 8.7 million species of plant and animal in existence. This means that millions of other organisms are still a mystery.

Biological diversity or Biodiversity:

Biodiversity refers to the diverse or varied forms of living beings which differ in exterior appearance, size, color pattern, internal structure, diet, behavior, habitat, and so on.

In other words ''the variety of life forms found in the particular region forms the biodiversity''.

Walter G. Rosen invented the word in 1986.

Taxonomy:

• It is a biological science which deals with the Identification, Nomenclature, and Classification of organisms.

• A. P de Candolle was coined in 1813.

Systematic: It is a scientific study of types and diversity of organisms and their comparative and evolutionary relationship.

Identification: It is to determine the exact place or position of an organism is set to the plant of classification.

Classification: It is the arrangement of organisms in hierarchical series of groups and subgroups based on similarities and differences in their traits.

Nomenclature: It is the process of providing scientific names to the organism.

Binomial Nomenclature: In biology, every organism is given to proper name first is the name of the genus to which and organisms belong. An organism’s second name is the name of the species to which it belongs. This approach of supplying a name with two components is termed binomial nomenclature.

Example: Rana (Genus) tigrina (species) = Frog

Binomial nomenclature was given by Carolus Linnaeus in his book entitled Species Plantarum in 1753.

Classification:

The method of arranging organisms into groups or set based on similarities and differences is called classification.

Importance of Classification:

Classification of a living organism has the following advantages:

• Classification means the study of a wide variety of organisms easily.

• Classification presents before us a view of all life forms at a glance.

• Understanding the interrelationships between different groupings of species requires classification.

Need of classification:

For the systemic study of animals, different animals are divided into major and minor groups based on similarities and differences, and each group is given a particular name depending upon their characteristics.

7 major taxa are used for the classification

• Kingdom

• Phylum/Division

• Class

• Order

• Family

• Genus

• Species

Species are the smallest taxon and are represented as a unit of classification/ taxonomy.

Evolution: The change of a species' features over multiple generations.

Artificial system of classification:

• This classification is based on morphological characters for the identification of plants such as habit, Habitat, shape of leaves, color, and number.

• Given by Carolus Linnaeus

The natural system of classification:

• This classification is based upon morphological as well as Anatomical relationships and affinities.

• Bentham and Hooker devised this system of classification.

Classification System: Living organisms have been classified according to different criteria:

Two kingdom classification:

In the two-kingdom classification of organisms are grouped based on the presence and absence of cell wall as proposed by Linnaeus.

Includes:

1. Plantae

2. Animalia

Five kingdom classification:

To develop phylogenetic classification, R. H Whittaker, in 1959 all the organisms into five kingdoms.

1. Monera

2. Protista

3. Fungi

4. Plantae

5. Animalia

Modern scheme of five kingdom classification:

In 1982, Margulis and Schwartz revised the five-kingdom classification. It includes one prokaryotic Kingdom - the prokaryotes and four Eukaryotic kingdoms- the Protocista, the fungi, the Plantae, and the Animalia. This scheme is a widely accepted one.

Taxonomical Hierarchy: Taxonomical Hierarchy is the process of arranging various organisms in two successive levels of the biological classification either in decreasing order and increasing order from Kingdom to species and vice versa.

Each of these levels of Hierarchy is called the taxonomic category or rank.

The kingdom is always listed first in this categorization scheme, followed by Division, Class, Order, Family, Genus, and Species.

Taxonomic Hierarchy Categories: Following are the important taxonomic hierarchy in which different organisms are classified:

• Kingdom: It includes all organisms who share a set of distinguishing common characters.

• Division/Phylum: It includes all organisms belonging to different classes having a few common characters.

• Class: It denotes creatures of related orders.

• Order: It is a mash-up of families with a few characters who resemble one another.

• Family: It is represented by a collection of related genera that are more similar to one another than to the genera of other families.

• Genus: It is a group of species that are related and have less character in common as compared to species.

• Species: It is a primary component for knowing taxonomy and evolution.

1. KINGDOM MONERA:

The Kingdom Monera is divided into two subs Kingdoms Archaebacteria and Eubacteria.

Archaebacteria:

• Most archaebacteria autotrophs and only a few, photosynthesize

• Archaebacteria derive the energy for their metabolic activity from the oxidation of chemical energy sources such as reduced gases- Ammonia(NH3), Methane (CH4), hydrogen sulfide (H2S). Archaebacteria can produce their own amino acids and proteins in the presence of one of these substances.

Archaebacteria are divided into the following three groups:-

1. Methanogens: They are found in swamps and marshes, in which all the oxygen has been consumed by the other organism living in those environments. In the presence of oxygen, methanogens die.

2. Thermoacidophiles: They are seen in hot springs.

3. Halophiles: They are seen in salty areas.

Eubacteria:

• It is called true bacteria

• The kingdom contains diverse types of bacteria having peptidoglycan cell walls, glycogen as a food reserve, naked DNA coiled to form nucleoid, absence of sap vacuoles, and presence of 70s ribosome.

• They include autotrophs [photosynthetic and chemosynthetic] and heterotrophs.

2. KINGDOM PROTISTA:

• This category contains a wide range of unicellular Eukaryotic species, including unicellular algae, protozoans, and fungus.

• Their mode of nutrition can be autotrophic (unicellular algae), or heterotrophic (protozoan).

• Example: Chlorella, Chlamydomonas, diatoms, and protozoans.

Phylum Protozoa:

• Protozoa are unicellular, usually aquatic creatures.

• The body is either bare or covered by pellicle or hard shells.

• Solitary or colonial, free-living or parasitic or symbiotic.

Protozoa are divided into the following five classes:

1. Mastigophora

2. Sarcodina

3. Sporozoa

4. Ciliata

5. Suctoria

3. KINGDOM FUNGI:

• Simple, non-photosynthetic non-green plants.

• They might be unicellular or filamentous in nature.

• Fungi have a cell wall containing a mixture of chitin cellulose.

• Glycogen is the reserve food of fungi.

• Example: Rhizopus, Saccharomyces, Neurospora.

4. KINGDOM PLANTAE:

• Plantae includes Multicellular organisms except for some primitive relatives of algae.

• The nutrition of plants is the autotrophic type with the help of chlorophyll present in chloroplast; plants can perform photosynthesis.

• Plants' reserve food is starch and lipids.

• Generally, growth in plants is indefinite due to the presence of growing points.

• Cellulose-containing cell wall occurs around the cell.

5. KINGDOM ANIMALIA:

• Animals have eukaryotic cells that lack a wall.

• The heterotrophic feeding of animals is of the holozoic type.

• The growth of animals is limited and stops after reaching maturity.

• Animals have an organization of cellular, tissue, organs, organ system levels.

• Animals have a distinct shape, size, and symmetry. Exceptions can be seen in certain lower forms.

Classification of kingdom Plantae:

Kingdom Plantae is further divided into various divisions based on various criteria:

1. Algae:

• Most primitive and simple plant.

• Most Algae are water growing or aquatic, some are terrestrial.

• Usually contain green pigment for photosynthesis; some algae have other photosynthetic pigments such as a Red, Brown, and purple.

• Mechanical and conducting tissue is absent.

• Spores are responsible for asexual reproduction in most cases.

• They have a cellulose cell wall around their cell.

• They are autotrophic and manufacture their own food.

Example: Green algae-Ulothrix, Red algae-Ulothrix, Batra, Brown algae - Focus.

2. Bryophyta:

• Bryophytes are multicellular Green Land plants that are modest in size.

• They lack a true vascular system.

• Their plant body is a flat, green thallus, in liverworts and leafy, erect structure in mosses.

• Sex organs are multicellular.

• Example: Riccia, Marchantia, Anthoceros.

3. Pteridophyta:

• They are found mainly in Damp places.

• The root, stem, and leaves comprise the plant's body.

• They have a well-developed vascular system that allows water and other nutrients to be transported from one region of the plant body to another.

• This plant has no flowers and does not produce seeds.

• Sex organs are multicellular, with sterile cells surrounding them.

Example: Club mosses-Selaginella, Horsetails-Equisetum

4. Gymnosperm:

• They are the most primitive and simple seed plants.

• The seeds produced by this plant and naked and are not included within fruits.

• Perennial, evergreen, and woody plants are the most common.

• Xylem is devoid of vessels, whereas phloem is devoid of companion cells.

• Gymnosperm includes the following two groups:

  1. Cyclades

  2. Coniferae

5. Angiosperms:

• Angiosperms are highly evolved plants and they produce seeds that are enclosed within the fruit.

• The reproductive organs are aggregated in flowers. Since these plants have flowers, they are called flowering plants.

• Plants embryo in seeds has structures, called cotyledons.

• The angiosperms are divided into two groups:

  1. Dicotyledons

  2. Monocotyledons

Classification of kingdom Animalia:

The main Phylum of kingdom Animalia is as follow:

1. Phylum Porifera:

• Sessile, Sedentary, and Marine except for one group that lives in Freshwater.

• The most basic multicellular, diploblastic creatures

• The body designs involve minimal differentiation and division into tissues.

• They are either asymmetrical or radially symmetrical in nature.

• Bodies perforated with a multitude of pores

• Skeleton is made up of minute calcareous or siliceous spicules or spongin fiber (collagen) or both.

• Reproduction is both sexual by budding and gemmules and sexual through fertilization.

Class 1. Calcarea. Example: Sycon

Class 2. Hexactinellida. Example: Euplectella.

Class 3. Demospongiae. Example: Spongilla.

2. Phylum Cnidarians or Coelenterata:

• Aquatic, mostly marine, a few such as Hydra are freshwater. Some of these species live in colonies (Physalia), while others live solitary (hydra).

• The body displays radial symmetry.

• Cnidarians or coelenterates are multicellular, diploblastic animals with tissue grade of organization.

• A central gastrovascular cavity coelenterate is present which lacks in the anus but has a mouth that is surrounded with short and slender tentacles.

• Development of respiratory, circulatory, or excretory organs is not seen.

• Polymorphism is seen in cnidarians.

• The nervous system is primitive has only a network of Nerve cells.

• The body shows two main forms, the polyps, and the Medusae.

Class1. Hydrozoa: Example: Hydra, Obelia

Class2. Scyphozoa. Example: Aurelia

Class 3. Anthozoa. Example: Fungia

3. Phylum Ctenophora:

• Transparent body with biradial symmetry. Triploblastic.

• They are marine, solitary, and free-swimming creatures.

• The nematocyst is absent but colloblasts (adhesive cells) are present.

• They do not show polymorphism or dimorphism.

• Two tentacles and 8 longitudinal rows of ciliary comb plates for locomotion are present.

• Example:-Pleurobrachia (combjelly), Cestum (venue's girdle).

4. Phylum Platyhelminthes: (Platys: flat; helminths: worm; Flatworm).

• They are dorsoventrally flattened and bilaterally symmetrical creatures.

• Their body is thin, delicate, and shaped like a leaf or a ribbon.

• They are Triploblastic creatures.

• Suckers and hooks are usually present.

• Hermaphrodite, i. e., both male and female reproductive organs occur in the same individual.

Example

Class 1. Turbellaria- Planaria, Dugesia

Class 2. Trematoda- Fasciola (lives fluke)

Class 3. Cestoda- Taenia solium (pork tapeworm)

5. Phylum Nematoda:

• The body is worm-like, cylindrical, or flattened.

• The body is covered with a tough, resistant cubicle; cilia absent.

• Straight and full alimentary canal with mouth and anus pharynx muscular.

• Their male and female are distinct.

• They are bilaterally symmetrical, triploblastic, pseudocoelomate, and unsegmented creatures.

• Most forms are parasitic (pathogenic) but some are free leaving in soil or water.

• Example: Ascaris (roundworm), Ancylostoma (hookworm), Wuchereria bancrofti (filarial worm).

6. Phylum Annelida: (Annelus - a ring; segmented worm)

• Body triploblastic, bilaterally symmetrical, soft, elongated, vermiform, and dorsoventrally flattened.

• Locomotory organs are segmentally arranged paired lateral appendages, parapodia or chitinous setae, or chaetae.

• True coelomate animals with closed blood vascular systems.

• The nervous system consists of a dorsal brain and a ventral nerve cord having ganglia and lateral nerves in each body segment.

• They are Mostly aquatic, marine, or freshwater, some are terrestrial, burrowing in tubes, some free-living forms are also seen.

Class 1. Polychaeta- Example: Nereis, Aphrodite

Class 2. Oligochaeta- Example: Pheretima (earthworm).

Class 3. Hirudinea- Example: Hirudinaria (Indian cattle leech).