Diversity in Living Organisms Class 9 Notes CBSE Science Chapter 7 (Free PDF Download)

1. What is the Basis of Classification?

• The form, structure, and manner of life of organisms differ. As a result, they should be classified together based on their similarities.

• The classification of closely related organisms aids in the study of their evolutionary links. 

• The categorization of organisms into groups and sub-groups based on their properties is known as classification. 

• A characteristic could be a specific shape or function.

Classification and Evolution:

• The majority of today's living forms are the result of a series of modifications in body design that enable the creature that possesses them to live better. 

• There's a chance that design complexity may rise through time, and it's not unreasonable to suggest that older species are simpler and younger organisms are more complicated.

The Hierarchy of Classification Groups:

• In Charles Darwin’s book, The Origin of Species, published in 1859, he proposed evolution. 

• Living species have been classified into kingdoms by scientists such as Ernst Haeckel, Robert Whittaker, and Carl Woese. 

• The ‘Five Kingdoms classification' of living beings was proposed by Robert Whittaker in 1969.

• Kingdom subgrouping into Phylum for animals and Division for plants, Class, Order, Family, Genus, and Species can be used to show the hierarchy. 

• As a result, the species is the fundamental unit of taxonomy. 

• All organisms that are similar to breed and produce fruitful offspring are classified as species.

• The sub-groups are further classified by naming them at various levels, as shown in the following system.

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3.1 Monera:

• Prokaryotic cells without a nucleus and membrane-bound cell organelles are included.

• Some have cell walls, whereas others don't. Some Monerans are autotrophic, whereas others are heterotrophic in nature. 

• Kingdom Monera includes bacteria, cyanobacteria, blue-green algae, and mycoplasma, etc.

3.2 Protista:

• Algae, diatoms, and protozoans are all part of it. 

• These are the simplest eukaryotes, being unicellular and capable of both autotrophic and heterotrophic feeding. 

• Whip-like flagella and hair-like cilia or finger-like pseudopodia allow locomotion and movement.

• Unicellular algae, diatoms, and protozoans are examples.

3.3 Fungi:

• These saprophytes are multicellular eukaryotic eukaryotes. 

• Chitin makes up the cell wall of fungus.

• They eat decaying and dead stuff. 

• Mushrooms, rhizopus, and mucor are among them. 

• Some fungus create a symbiotic relationship with algal cells. 

• Lichens are the name given to these symbionts.

3.4 Plantae:

• All non-motile, multicellular, and eukaryotic creatures with cellulose-based cell walls are included in this category. 

• These are sophisticated organisms capable of photosynthesis. 

• Plants are made up of cells that have thick cell walls.

3.5 Animalia:

• It refers to all animals that are motile, multicellular, eukaryotic entities with no cell walls. 

• It demonstrates a wide range of species. 

• Members of this kingdom are multi-tissue creatures.

4. Plantae

4.1 Thallophyta:

• According to Eichler, Cryptogamae and Phanerogamae are two sub-kingdoms of the plant kingdom.

• Cryptogamae - Plants having hidden reproductive organs that do not bear flowers or seeds belong to this sub-kingdom. 

• Thallophyta, Bryophyta, and Pteridophyta are the three subgroups of cryptogams.

• Thallophyta are the most basic of plants, with no discernible body structure. 

• Algae is the popular name for the plants in this group. 

• These are primarily aquatic in nature. 

• Spirogyra, Ulothrix, Cladospora, and Chara are other examples.

• Bryophytes are known as the plant kingdom's amphibians because they require both aquatic and terrestrial conditions to complete their life cycle. 

• Differentiation of the plant body to create stem and leaf-like structures is widespread. 

• Moss or Funaria are examples.

• Pteridophyta are fern plants with a plant body that is divided into stems, leaves, and roots. 

• Underneath the leaf, they have naked embryos in the form of spores.

• Phanerogamae :

• Plants that produce seeds and have well-formed stems, leaves, and roots belong to this sub-kingdom. 

• Gymnosperms and Angiosperms are the two types of Phanerogams.

• Gymnosperms:

• The first plants to have a seed habit were Gymnosperms. 

• These are plants that have no seeds and are perennial, evergreen, and woody in nature. 

• Pinus, cycas, and deodar are the examples.

• Angiosperms:

• Flowers, fruits, and seeds are all found in angiosperms, which are highly evolved plants bearing flowers, fruits, and seeds.

• Flowering plants are another name for them. 

• The seeds of these plants are contained within the fruit of these plants. 

• The seed sprouts and grows into a new plant. 

• Cotyledons are structures found in plant embryos and seeds.

• Seed leaves, also known as cotyledons, indicate a pre-designed plant in the seed. 

• Angiosperms are split into two groups based on the number of cotyledons they have: monocots and dicots. 

• Paphiopedilum is a monocot, whereas Ipomea is a dicot.

Animalia:

• These are organisms which are eukaryotic, multicellular and heterotrophic. 

• Their cells do not have a cell wall. 

• The majority of animals are mobile. 

• Animals are classed based on characteristics such as cellular or tissue-level body organisation, body symmetry, coelom type, presence or absence of segmentation, and presence or absence of a backbone.

• Animalia is divided into two kingdoms: Invertebrata dan Vertebrata.

5.1 Invertebrata:

• It refers to a group of animals that lack a vertebral column. 

• Porifera, Coelenterata, Platyhelminthes, Nematoda, Annelida, Arthropoda, Mollusca, and Echinodermata are some of the phyla of invertebrates.

1. Porifera:

• Porifera are multicellular creatures with only rudimentary tissue organisation. 

• They do not have a neurological system. 

• These aren't mobile at all. 

• All across the body, there are openings called pores. 

• These creatures have a hard outer covering, or skeleton, that protects them from the elements. 

• Sponge is a frequent name for them. 

• Sycon, Spongilla, and Euplectella are all members of the Porifera family.

2. Coelenterata:

• Coelenterates are water-dwelling, radially symmetrical creatures. 

• Some are isolated, while others are colonial.

• They have a more distinct body design. 

• The body has a hole in it.

• Corals, Hydra, and sea anemones are the examples.

3. Platyhelminthes:

• Platyhelminthes can be parasitic or free-living. 

• They are triploblastic and bilaterally symmetrical animals.

• There is some tissue body cavity or coelom present. 

• Flatworms are what they're called. 

• Planaria (free-living) and liver fluke (parasite) are the examples.

4. Nematoda:

• Nematodes are parasitic worms that are bilaterally symmetrical and triploblastic. 

• The body is spherical. 

• There is a pseudo coelom present.

• Elephantiasis, for example, is a disease caused by them.

5. Arthropoda:

• Arthropoda animals have true coelom and are bilaterally symmetrical, segmented, triploblastic animals. 

• Insects are among them. 

• Their legs are joined. 

• Blood does not pass through blood vessels since their circulatory system is open. 

• For example, prawns, butterflies, and other insects.

6. Molluscs:

• Molluscs are triploblastic animals with a reduced coelom that are bilaterally symmetrical. 

• Molluscs move about by using a muscular foot. 

• They don't have a lot of segmentation. 

• They have an open circulatory system and excretion organs that resemble kidneys. 

• Pila, Unio, and octopus are the examples.

7. Echinodermata:

• Echinodermata animals have a true coelomic cavity and are triploblastic. 

• Echinodermata are creatures with a spiky skin. 

• Echinoderm skeletons are made up of rigid calcium carbonates.

• They are symmetrical in the radial direction. 

• Starfish and sea urchins are examples.

8. Protochordata:

• These primitive chordates are bilaterally symmetrical, triploblastic, and have a coelom. 

• During their early stages of development, protochordates have a notochord.

• The notochord is a long rod-like structure that runs the length of the animal's back, dividing the neurological and digestive systems. 

• Balanoglossus, Herdmania, and Amphioxus are examples of marine animals.

5.2 Vertebrata:

• These animals are the most advanced, with a real vertebral column and a strong endoskeleton. 

• Bilateral symmetry, notochord, dorsal nerve cord, paired gill pouches, triploblastic, and coelomate are all used to classify vertebrates. 

• Pisces, Amphibia, Reptilia, Aves, and Mammalia are the five classes.

1. Pisces:

• All fish are included in Pisces. 

• These are scale-covered aquatic cold-blooded creatures. 

• The body is streamlined, and movement is provided by a muscular tail. 

• Fish use their gills to breathe. 

• The skeleton can be cartilaginous or bony. 

• They have a two-chambered heart and lay eggs to reproduce.

• Torpedo, Mandarin fish, Stingray, and so on.

2. Amphibians:

• Cold-blooded creatures are amphibians. 

• Amphibians are creatures that can live on land and in water.

• Gulls and lungs are used to breathe. 

• They have a heart with three chambers. 

• Laying eggs is how amphibians reproduce. 

• Frogs, toads, and salamanders are examples.

3. Reptilia:

• Reptilia are cold-blooded animals that breathe via their lungs and have scales. 

• Except in crocodiles, the heart has three chambers. 

• Reptiles reproduce by laying eggs as well. 

• Snakes, crocodiles, lizards, turtles, and other reptiles are examples.

4. Aves:

• The avengers are warm-blooded creatures. 

• Their forelimbs have been changed to allow them to fly. 

• Bones have a hollow interior.

• Feathers cover the body.

•  Lungs are used to breathe. 

• They have a heart with four chambers.

• They produce eggs.

• Crow, ostrich, and sparrow are the examples.

5. Mammals:

• Mammals have four chambered hearts and are warm-blooded animals. 

• Hair, sweat glands, and oil glands cover their skin, which helps to regulate body temperature. 

• Mammals give birth to their offspring.

• They have mammary glands that produce milk in order to feed their offspring. 

• Platypuses lay eggs. 

• Kangaroos give birth to young that are underdeveloped and carried in their mother's abdominal pouch.

• Humans, rats, cats, etc are the examples.

Diversity in Living Organisms Class 9 Notes

Class 9th Science chapter 7 notes cover the hierarchy of classification groups. The grouping is done in terms of Phylum for animals or Division in case of plants. Those are followed by Class, Order, Family, Genus and Species. Species amount to be the basic unit of classification.

The classification of kingdoms is:

1. Monera

The prokaryotic cells lack cell membrane and organised nucleus. It can be both autotrophic and heterotrophic. Examples are bacteria, cyanobacteria, mycoplasma etc.

2. Protista

Protista is the simplest form of unicellular eukaryotes. Flagella or cilia may be present for movement and locomotion. Examples are diatoms, algae and protozoans.

3. Fungi

Notes of Science class 9 chapter 7 explain fungi as multicellular and eukaryotic saprophytes. The cell wall is composed of chitin. Its nutrition comes from decaying and dead matter. Examples of fungi are rhizopus, mushrooms and mucor.

4. Plantae

Plantae includes all plants which are multicellular, non-motile, and eukaryotic organisms. The cell walls are composed of cellulose. The walls are also thick.

Notes for class 9 Science chapter 7 mention the sub-groups as:

• Thallophyta

The plant body is not well differentiated in Thallophyta. Examples are – Ulothrix, Spirogyra, Chara.

• Bryophyta

Notes of ch 7 Science class denote Bryophytes as amphibians of the plant kingdom. It is because it can thrive both in terrestrial and aquatic conditions. Examples are Funaria, Moss.

• Pteridophyta

It primarily includes plants which have a well-differentiated body in the form of leaves, stem, and roots.

5. Animalia

Animalia has discussed in ch 7 Science class 9 notes as multicellular, eukaryotic, and heterotrophic. However, there is no cell wall.

The subgroups are Invertebrata and Vertebrata.

Invertebrata has the following classification as mentioned in chapter 7 class 9 Science notes:

• Porifera: Multicellular organisms showing very less tissue organisation.

• Coelenterata: Radially symmetrical organisms.

• Platyhelminthes: Triploblastic or bilaterally symmetrical.

• Nematode: Cylindrical body with pseudo coelom.

• Annelida: Presence of a proper body cavity.

• Arthropoda: Segmented, bilaterally symmetrical and triploblastic with the presence of true coelom.

• Molluscs: Muscular foot present for locomotion.

• Echinodermata: Skeletons made from calcium carbonate and possess spiny skin.

Diversity in living organisms class 9 notes helps the students in arriving at a clear understanding of the chapter. If students still have confusion regarding this chapter, Vedantu's online classes can be of help. Download the app now!