Aristotle classed creatures according to how they interacted with their surroundings, as mentioned in the Diversity In Living Organism Chapter 9. As a result, he divided them into two categories: aquatic and terrestrial. However, some animals and plants may be found both in the water and on land. Furthermore, there are both extremely little creatures, such as the seahorse, and gigantic animals, such as the whale. As a result, this was an inadequate foundation for categorisation, and other bases were worked into.

• Is a nucleus present in the cell?

On the basis of this, there are two main categories of living organisms as mentioned in the Biology Class 9 Diversity In Living Organisms. The eukaryotes and the prokaryotes. Prokaryotes are organisms whose cells do not have a well-defined nucleus, such as bacteria. Eukaryotes, on the other hand, are creatures that have cells with a clearly defined nucleus and are thus classified as such. Cells function more efficiently when they have a nucleus and organelles that are attached to the membrane.

• Number of cells

Based on this, the organism can be seen as unicellular or multicellular. Unicellular organisms are creatures that only have a single cell and do not have any other cells. In these organisms, a single cell is responsible for performing all of the processes required to sustain life on Earth. Multicellular organisms, on the other hand, are creatures that include more than one cell and are thus referred to as such. Because of the increased number of cells, it may be possible to divide work in order to increase efficiency.

• Method of Nutrition 

Autotrophs are creatures that produce their own nourishment as a result of this process. All green plants are autotrophs, which means they produce food for themselves. They contain a pigment (chlorophyll) in their green parts, which aids in photosynthesis, while creatures that are reliant on either plants or animals are referred to as heterotrophic organisms. The absence of chlorophyll makes them inert. This category includes all mammals, fungi, and some bacteria and protozoa, among others.

• Level of body organisation 

Diversity In Living Organism Class 9 mentions that individual cell groups in tiny multicellular animals like hydra are allocated specific functions in order to maximise their productivity. The opposite is true in bigger organisms when tissues come together to form an organ, which in turn form organ systems. Examples include the fact that human beings have various systems for carrying out particular body functions.

Even in bigger plants, there is a distinct root system for the transportation of water and nutrients, a leaf system for photosynthesis, and flowers for reproduction. Organisms may be further categorised into subgroups based on the characteristics that they exhibit.

• Evolutionary or Phylogenetic Relationship

As seen in Diversity In Living Organism Class 9, In 1859, Charles Darwin published his book "Origin of Species" in which he explained his views of evolution. All species, according to his views, have descended from single-celled organisms. 

Primary body designs appeared early in evolutionary history and were followed by increasingly complex forms as time progressed. This resulted in a tremendous amount of variation in the variety of living forms. 

All creatures are connected to one another because they have a common ancestor. It is also one of the fundamental principles of categorisation that a closer evolutionary relationship exists between two animals.

As shown in the Diversity In Living Organisms Chapter 9, Ernst Haeckel (1894), Robert Whittaker (1959) and Carl Woese (1977) attempted to divide all living species into broad divisions known as kingdoms.

The main five categories of Kingdoms under Whittaker Classification of organisms, as mentioned in diversity in living organism class 9, are 

• Monera

• Protista

• Fungi

• Plantae

• Animalia

Beyond Kingdom, these scientists divided organisms into various other categories under kingdoms, basing arguments on different traits for each organism and coming up with these subcategories. 

• Phylum and Division for animals and plants, respectively 

• Class

• Order

• Family

• Genus

• Species

As a result, by dividing creatures into smaller and smaller groupings on the basis of a hierarchy of features, we arrive at the fundamental unit of categorisation, which is the species. A species is defined as any group of creatures that are genetically similar enough to reproduce and survive.

• Kingdom Monera 

These creatures lack a distinct nucleus or organelles and are hence unicellular in nature. Some species within this category have cell walls that are similar to theirs. It doesn't matter whether they are autotrophic or heterotrophic in their nutritional mechanism. Bacteria and blue-green algae are examples of organisms that belong to this kingdom.

• Kingdom Protista

The chapter Diversity In Living Organism Class 9 mentions that Eukaryotic creatures possess just one cell.

In some members, they move about by utilising cilia, which are hair-like structures, or flagella, which are whip-like structures. Both autotrophic and heterotrophic modes of nourishment are possible for them. Algae, protozoans (Plasmodium, Entamoeba) and other organisms are examples.

• Kingdom Fungi 

Fungal creatures include microorganisms such as yeast, moulds and mushrooms, which are classified as eukaryotic organisms (which means they are made up of cells with a well-defined nucleus). Fungi are the kingdom in which these species are categorised. A cell wall is present in the creatures found in the Kingdom Fungi, and they are widely distributed around the world. The living creatures that they are categorised as are heterotrophs.

• Kingdom Plantae

Plantae is the kingdom that comprises terrestrial plants as well as green algae, among other things. Photosynthesis is carried out by multicellular, autotrophic eukaryotes that belong to Plantae.

• Kingdom Animalia

Animals of all kinds are considered members of the Kingdom Animalia. In most animals, the body is made up of cells that are organised into tissues, with each tissue being specialised to a certain degree in order to fulfil certain duties. Most tissues are organised into organs that are considerably more specialised. They are all heterotrophic.

As you can see in the Class 9th Science Diversity In Living Organisms, the kingdom Plantae is classified into a number of groups.

• Thallophyta or Algae:

Undifferentiated plants. 

This category of plants is called algae. These plants are aquatic. Spirogyra, Ulothrix, Cladophora and Chora are some examples.

• Bryophyta:

They are the plant kingdom's amphibians. Branches and leaves are typical plant body structures. However, there is no specific tissue for transporting water and other chemicals throughout the plant’s body. Examples include Moss and Marchantia.

• Pteridophyta:

The plant body is divided into roots, stems, and leaves, with specialised tissue for water and other substance transport. Examples include marsuea, ferns and horsetails.

• Gymnosperms:

These are plants that produce only seeds and are typically perennial, evergreen, and woody in their growth. Pines and deodar are examples of such plants.

• Angiosperms 

The term Angiosperm is made up of two Greek words: angio, meaning covered, and sperma, meaning seed. An organ that develops into a fruit containing the seeds belongs to this category. These are blooming plants. Cotyledons are seed-borne plant embryonic structures.

• Cotyledons:

One or more of the earliest leaves that emerge from a germinating seed is referred to as a cotyledon, which is a vital portion of the embryo within the seed of a plant. Botanists utilise the number of cotyledons present to classify flowering plants.

They are classified as monocots with a single cotyledon and dicots with dual cotyledons.

1. What is the need for classifying organisms?

Classifying organisms helps us differentiate and group organisms into different categories and study their characteristics individually. The similarities found between living organisms help us categorise them into classes and groups, which are very useful in research.

2. Mention four ranges of variations of life-forms around you.

Answer

(a) Birds and cats

(b) Fishes in the sea

(c) Rose plants

(d) The bacteria in curd

 

3. What's the most primary characteristic for the first division of organisms?

Answer

The nature of a cell is one of the primary characteristics of what the first division of organisms is decided. The life forms are divided into eukaryotes and prokaryotes.

4. How are plants and animals put into categories?

Answer

Animals and plants are categorised on the basis of:

1. The absence or presence of a cell wall

2. The mode of nutrition

These were some of the most important Diversity In Living Organisms Class 9 Solutions that you are important for the future preparation.

Biology is one such subject that’s important for you to understand to make a future in the field and enter the field of organisms and medicine.