CBSE Notes for Class 9 Chapter 7 Diversity in Living Organisms
Chapter 7 Diversity in Living Organisms CBSE Notes for Class 9: We have studied how different organisms are made from cells, tissue, and organs in detail. In this article, you will get CBSE Class 9 Science notes for chapter 7 Diversity in Living Organisms. We see a lot of organisms around us, but do you think we all look the same? No, right. On this earth, humans have the same structure as the nose, ears, hands, and legs. On the other hand, cows have a little more different ears, eyes, and more when compared to humans. Different types of organisms are present around us from small bacteria to big whales. And, we really don’t have time to look at organisms one by one. So, here this chapter has made this easy for the students. Classification of living things plays a vital role when it comes to understanding various kinds of organisms. Let us have a look at the below notes to know more about Diversity in Living Organisms.
Introduction to Classification
On the basis of where a particular animal lives in water, land, or air, the Greek Aristotle was the one who classified animals. But this classification was not acceptable in other cases. They have been classified as whales, corals, and octopuses living in the water so they have only one habitat in common to share. Organisms that live in water have different structures, different patterns, systems, appearances, etc. Then, classification only on the basis of habitat is not a proper way to classify animals. Hence, the groups and their sub-groups are created to classify animals separately without any confusion. Various organisms are then decided to group together on the basis of their characteristics. Having one thing in common like we all have two eyes, is an example of characteristics.
Some characteristics of the hierarchical classification
- Some eukaryotic cells have a well-identified nucleus and other organisms do not have a nucleus in their cell. This can be a basic characteristic to classify organisms.
- In other cases, few organisms like plants can make their own food through the photosynthesis process. But, other organisms get food from outside. This feature makes difference between organisms.
- In the characteristics of hierarchical classification, the body design is also a characteristic that makes a difference between amoeba and earthworms.
Relation between classification and evolution
As time goes the species exits and evolves themselves according to changes to survive better. Evolution makes a difference in the characteristics of organisms. Living organisms are also classified into different groups according to their features. Hence, the classification is closely related to the evolution of living organisms. In 1859, the idea of evolution was described firstly by Darwin in The Origin of Species book. Organisms that are placed in the very first group are also called primitive or lower organisms. Those who are placed in the second group are known as higher or advanced organisms.
Biodiversity
Biodiversity is referred to as the diversity of living forms which can be found in specific regions. Sometimes, living forms affect each other and live in a common environment. When the diversity of both animals and plants is found in the tropical regions between the tropic of Cancer and the tropic of Capricorn then it is known as the Region of Megadiversity.
Hierarchy of Classification
A broad category in which all living organisms are classified is known as Kingdoms. All living organisms are broadly classified into groups on the basis of mode of nutrition, cell structure, and body organization by three biologists, such as Ernst Haeckel, Carl Wiese, and Robert Whittaker. The Whittaker grouped different organisms into five kingdoms: Monera, Protista, Fungi, Plantae, and Animalia. The Monera was divided into Archaebacteria and Eubacteria by the Woese.
Levels of Classification
Kingdom
The highest level of classification (Kingdom) where similar characteristics of phyla or divisions are included.
Phylum Or Division
A Level of classification (Phylum) where similar characteristics of classes are included.
Class
A level of classification (Class) where similar characteristics of orders are included.
Order
A level of classification (Order) where similar characteristics of families are included.
Family
The level of classification (Family) where similar characteristics of genus are included.
Genus
The level of classification (Genus) where similar characteristics of species are included.
Species
The level of classification Species have the ability to reproduce and it includes similar characteristics of organisms.
Five kingdom classification
Monera
Important Characteristics:
- A defined nucleus or organelles and multicellular body designs are not present in the organisms of Monera.
- In all the prokaryotic organisms, the mode of nutrition is autotrophic in some cases and heterotrophic in other cases.
- Organisms such as mycoplasma, cyanobacteria, and blue-green algae are included in the Kingdom Monera.
Protista
Important Characteristics
- Kingdom Protista contains many unicellular types of Eukaryotic organisms.
- These organisms have hair-like cilia and whip-like flagella for movement.
- Some organisms have an autotrophic mode of nutrition and the remaining have a heterotrophic mode.
- Unicellular algae, protozoans, and diatoms are examples of Kingdom Protista.
Fig 1. Amoeba
Fungi
Important Characteristics
- In the organisms, the mode of nutrition is the heterotrophic type and they are eukaryotic organisms.
- Also, some of the organisms of Protista show a saprotrophic (organisms that take the decaying organic matter as food) mode of nutrition.
- At a later stage, where some organisms become multicellular they possess a cell wall of chitin.
- In addition, few species of fungi show a symbiotic type of relationship. Life forms of symbiotics are also known as lichens.
Plantae
Important Characteristics
- Multicellular eukaryotes are present in the organisms of the kingdom Plantae.
- In these organisms, chlorophyll is present for photosynthesis. They have a cell wall and mainly include plants.
- Subgroups of this category are also there because plants are present everywhere when we see them.
Kingdom Plantae is then classified into different categories where characteristics like tissue, seeds are enclosed within fruits of not, and bearing seeds are compared. Further classifications of kingdom Plantae are as follows:
1.) Thallophyta
Organisms of this group do not have well-differentiated bodies. Plants that are present in the Thallophyta group are known as Algae. Ulva, Ulothrix, Chara, Spirogyra, and Cladophora are examples of this group.
2.) Pteridophyta
In the Pteridophyte, the body of plants is divided into the stem, roots, special, and leaves. Some plants that have spores or hidden reproductive parts are called Cryptogamae. When the plants reproduce seeds for reproduction then they are called Phanerogamae. Angiosperms and Gymnosperms are included in the classification on the basis of whether plants have naked seeds and seeds that are enclosed in fruits.
3.) Bryophyta
Organisms of Bryophyta are also referred to as Amphibians of the plant kingdom. The formation of leaf-like structure and stem takes place in the plant body of this group. In this group, specialized tissues are absent that truly help to conduct water. Moss and Marchantia are examples of Bryophyta.
4.) Angiosperms
The flowering plants or the plants that have covered seeds are known as Angiosperms. In the seeds, structures that are present in the plant embryos are known as Cotyledons. Monocotyledonous plants have a single cotyledon in the plant seed. On the other side, Dicots have two cotyledons in plant seeds.
5.) Gymnosperms
The plants having naked seeds are grouped into Gymnosperms. These are perennial, woody, and evergreen plants. Pine is an example of a gymnosperm.
Animalia
- Organisms that are multicellular and heterotrophic are included in the kingdom Animalia.
- Most animals show either bilateral symmetry, asymmetry, or radial symmetry.
- Also, animals have organ systems that help them to survive in a better way.
- Animals are mostly mobile, Eukaryotes, heterotrophic, multicellular, and have cells without a cell wall. Further classification of animals is as follows:
1.) Porifera
The organisms with pores are part of this group Porifera. They live in marine habitats and have a canal system for circulation. Spongilla, Sycon, and Euplectella are examples of Porifera.
2.) Coelenterata
The animals of Coelenterata are found living in colonies of aquatic habitats and many body design differentiations are shown. Examples of this group are jellyfish and anemones.
Fig 2. Hydra
3.) Platyhelminthes
In this group, animals have complex body designs and bilaterally symmetrical bodies. If the tissue of animals is composed of three layers of cells then it is called Triploblastic. Animals of Platyhelminthes are also known as flatworms because their body is dorsoventrally flattened.
4.) Nematoda
The body of a Nematode consists of three layers of cells and shows bilateral symmetry. Real organs are absent and only tissue is present in these organisms. They are also well-known as parasitic worms that are responsible for causing diseases.
5.) Annelida
A special characteristic rather than triploblastic and bilaterally symmetrical is the presence of a true body cavity. The animals are present in all kinds of habitats such as land, marine, and freshwater. Examples include leeches and Earthworms.
6.) Arthropoda
The group Arthropoda is the largest among animals. The body of animals is segmented and bilaterally symmetrical. The meaning of ‘Arthropoda’ is joined appendages. Scorpions, crabs, prawns, and houseflies are examples of Arthropoda.
7.) Mollusca
Organisms of this group show little segmentation and bilateral symmetry. In the Mollusca animals, an open circulatory system and organs which look like kidneys are present.
8.) Echinodermata
Animals having spiny skin are called Echinodermata. These are marine animals with a coelomic cavity, three layers of the cell (Triploblastic), the skeleton of calcium carbonate, and a tube system for movement. Sea stars and sea urchins are examples of the Echinodermata group.
9.) Protochordata
In this group of marine animals, both coelom and rod-like notochord are present. Herdmania, Amphioxus, and Balanoglossus are some of the examples.
Fig 3. Balanoglossus
10.) Vertebrata
Animals that have triploblastic layers, segments, paired gill pouches, complex differentiation of body tissue, and a true vertebral column are the vertebrates. Vertebrates are later divided into six classes which include:
a) Cyclostomata
Characteristics- Jawless vertebrates, slimy skin, circular mouth, eel-like body, etc.
Examples- Myxine and Petromyzon
b) Pisces
Characteristics- Aquatic animals, scaly skin, gills to dissolve oxygen, two-chambered hearts, muscular tails, and a streamlined body for movement.
Examples- Lionfish and Angular fish
c) Amphibia
Characteristics- Three chambered heart, mucous glands in akin, gills or lungs for respiration, lay eggs, and live in water as well as land.
Examples- Salamander and Frogs.
d) Reptilia
Characteristics- Three or Four chambered hearts, cold-blooded, scales and lungs are present and lay eggs.
Examples- Crocodiles, Snakes, and Turtles.
e) Aves
Characteristics- Warm-blooded animals with four-chambered hearts,, presence of feathers, have lungs, and lay eggs.
Examples- All Birds
f) Mammalia
Characteristics- Mammary glands are present (Reproduction), Warm-blooded animals, have four-chambered hearts, oil glands, sweat glands, hairs, ability to produce young ones.
Examples- humans, rats, and cats.
Nomenclature
Nomenclature terms are introduced by Carolus Linnaeus which includes a method of naming.
Some important rules while writing the scientific names
- The initial of Genus’s name should be in capital letters.
- The initial of the species name should be in Small letters.
- The scientific name should be written in Italics when it comes to printing.
- The species and genus name should be underlined when written by hand.
Important Faq on CBSE Notes Class 9 Diversity in Living Organisms:
What is the definition of ‘Binomial Nomenclature’?
The standard naming system which is introduced to reduce confusion while identifying organisms is called Binomial Nomenclature.
Why scientific naming of organisms is needed?
On this planet, people use different languages for communication. The scientific names are important to avoid confusion among people who speak different languages. The scientific names will help different people to understand the names of organisms. Hence, the scientific names of organisms are required.
What are the examples of the Aves group?
Ostrich, Crow, Pigeon, Sparrow, and White Stork are birds that are categorized under the Aves group.
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