Diversity in Living Organisms class 9 Notes

Introduction

The Earth is home to a huge variety of living organisms. From tiny microscopic bacteria to giant elephants and tall trees, life exists in many different forms. This variety of living forms is called biodiversity.
The chapter “Diversity in Living Organisms” helps us understand how and why living organisms are different from each other and how scientists classify them into groups for easy study.
The five-kingdom classification was proposed by Robert Whittaker in 1969, and Monera was placed as the first kingdom because it contains the most basic forms of life.

What is Diversity?

Diversity means variety.
In biology, diversity refers to the wide range of different types of plants, animals, and microorganisms found on Earth.

Examples:

Plants like mango tree, cactus, and grass
Animals like lion, fish, and butterfly
Microorganisms like bacteria and fungi

Why Do We Classify Living Organisms?

Because there are millions of species on Earth, it becomes difficult to study them individually. So scientists group them based on similarities and differences. This process is called classification.

Classification helps to:

Identify organisms easily
Understand similarities and differences
Study evolution
Avoid confusion in naming

Five Kingdom Classification

The five-kingdom classification system was proposed by Robert Whittaker in 1969.
The five kingdoms are:

1) Monera

2) Protista

3) Fungi

4) Plantae

5) Animalia

1) Monera

Kingdom Monera includes the simplest and most primitive living organisms. These organisms are unicellular and prokaryotic, meaning they do not have a true nucleus or membrane-bound organelles.

Main Characteristics of Monera

1) Unicellular (single-celled organisms)

2) Prokaryotic cells (no true nucleus)

3) No membrane-bound organelles (no mitochondria, ER, etc.)

4) Cell wall usually present (made of peptidoglycan in bacteria)

5) Reproduce mainly by binary fission

6) Can live in extreme environments

Cell Structure of Monera

Genetic material is not enclosed in a nucleus\
DNA is present in a region called nucleoid
Ribosomes are present
Some have flagella for movement

Nutrition in Monera

Monerans can have different modes of nutrition:

1) Autotrophic

Make their own food
Example: Some bacteria and cyanobacteria

2) Heterotrophic

Depend on others for food
May be:
- Saprophytic (feed on dead matter)
- Parasitic (live on host)

Types of Organisms in Monera

1) Bacteria

Found everywhere: soil, air, water, inside living organisms
Shapes:
- Cocci (round)
- Bacilli (rod-shaped)
- Spirilla (spiral-shaped)

2) Cyanobacteria (Blue-Green Algae)

Photosynthetic bacteria
Example: Nostoc, Anabaena

Reproduction in Monera

Mainly by binary fission (one cell divides into two)
Can also form spores in unfavorable conditions

Importance of Monera

Some bacteria help in digestion
Used in making curd and antibiotics
Help in nitrogen fixation
Some cause diseases (cholera, TB, typhoid)

2) Protista

- Protista includes unicellular (single-celled) eukaryotic organisms.

They have a true nucleus
They have membrane-bound organelles
Mostly live in water or moist places

Characteristics of Protista

Cell Type – Eukaryotic
Cell Structure – Mostly unicellular (some are colonial)
Habitat – Aquatic (ponds, rivers, sea)
Nutrition –
- Autotrophic (make their own food)
- Heterotrophic (depend on others)
- Some are mixotrophic (both)
Movement –

By cilia
By flagella
By pseudopodia

Types of Protists

1) Protozoa (Animal-like Protists)

Heterotrophic
Move using cilia, flagella or pseudopodia

Examples:

Amoeba proteus – moves by pseudopodia
Paramecium caudatum – moves by cilia
Plasmodium falciparum – causes malaria

2) Algae (Plant-like Protists)

Autotrophic
Contain chlorophyll
Photosynthesis occurs

Examples:

Chlamydomonas reinhardtii
Volvox carteri

3) Fungus-like Protists

Heterotrophic
Live in moist places

Example:

Physarum polycephalum

Reproduction in Protista

Mostly asexual reproduction
- Binary fission
Some show sexual reproduction
- Conjugation (in Paramecium)

Importance of Protista

Base of aquatic food chain
Produce oxygen (algae)
Some cause diseases (e.g., malaria)
Used in research

3) Fungi

- Fungi are non-green, heterotrophic, eukaryotic organisms.

They cannot make their own food (no chlorophyll)
They absorb food from dead or living organisms
Mostly grow in moist and warm places

Characteristics of Fungi

1) Cell Type – Eukaryotic
2) Nutrition – Heterotrophic (saprophytic / parasitic / symbiotic)
3) Cell Wall – Made of chitin
4) Body Structure – Made up of thread-like structures called hyphae
4) Network of hyphae is called mycelium
5) Reproduction – By spores

Modes of Nutrition

1) Saprophytic

Feed on dead and decaying matter
Example: Rhizopus stolonifer

2) Parasitic

Live on living organisms and harm them
Example: Puccinia graminis

3) Symbiotic

Live together with other organisms for mutual benefit
Example: Lichen (Fungus + Algae association)

Examples of Fungi

Saccharomyces cerevisiae (Yeast – unicellular)
Agaricus bisporus (Mushroom)
Penicillium chrysogenum

Reproduction in Fungi

1) Asexual Reproduction

By spores
By budding (in yeast)
By fragmentation

2) Sexual Reproduction

Formation of special spores

Importance of Fungi

Used in making bread, cake (Yeast)
Used to produce antibiotics (Penicillin)
Decompose dead matter (maintain environmental balance)
Some cause diseases in plants and human

4) Plantae

- Plantae includes all multicellular, eukaryotic, green plants.

They:

Contain chlorophyll
Prepare their own food by photosynthesis
Have a cell wall made of cellulose

Characteristics of Plantae

1) Cell Type – Eukaryotic
2) Cell Structure – Multicellular
3) Cell Wall – Made up of cellulose
4) Nutrition – Autotrophic (photosynthesis)
5) Movement – Non-motile (fixed in one place)
6) Reserve Food – Stored as starch

Classification of Kingdom Plantae

- Plants are divided into five main groups:

1) Thallophyta (Algae)

Body not differentiated into root, stem, leaves
Mostly aquatic

Examples:

Spirogyra
Ulva lactuca

2) Bryophyta

Small plants
No true roots, stem, or leaves
Called “Amphibians of plant kingdom”

Example:

Funaria hygrometrica

3) Pteridophyta

Have true roots, stem, and leaves
Reproduce by spores

Example:

Nephrolepis exaltata

4) Gymnosperms

Seed-bearing plants
Seeds are naked (not inside fruit)

Example:

Pinus roxburghii

5) Angiosperms

Flowering plants
Seeds are enclosed inside fruit
Divided into:
- Monocots
- Dicots

Example:

Mangifera indica

Importance of Plants

Produce oxygen
Provide food
Give medicines and wood
Maintain ecological balance

5) Animalia

- Animalia includes all multicellular, eukaryotic, heterotrophic organisms commonly called animals.

They:

Cannot make their own food
Do not have a cell wall
Usually show movement

Characteristics of Animalia

1) Cell Type – Eukaryotic
2) Cell Structure – Multicellular
3) Cell Wall – Absent
4) Nutrition – Heterotrophic (ingest food)
5) Movement – Mostly motile
6) Growth – Definite growth pattern
7) Nervous System – Well developed in higher animals

Classification of Animalia

Animals are divided into two main groups:

1) Invertebrates (Without Backbone)

a) Porifera

Body full of pores
Aquatic animals

Example:

Sycon ciliatum

b) Coelenterata (Cnidaria)

Radial symmetry
Have tentacles

Example:

Hydra vulgaris

c) Platyhelminthes

Flatworms
Mostly parasitic

Example:

Taenia solium

d) Nematoda

Roundworms

Example:

Ascaris lumbricoides

e) Annelida

Segmented worms

Example:

Pheretima posthuma

f) Arthropoda

Jointed legs
Largest animal phylum

Example:

Periplaneta americana

g) Mollusca

Soft body
Mostly have shells

Example:

Pila globosa

h) Echinodermata

Spiny skin
Marine animals

Example:

Asterias rubens

2) Vertebrates (With Backbone)

Belong to Phylum Chordata.

1. Pisces (Fishes)

Characteristics

Live in water
Body covered with scales
Breathe through gills
Have fins for swimming
Cold-blooded animals
Heart has two chambers

Examples

Labeo rohita
Carcharodon carcharias

2) Amphibia

Characteristics

Live both on land and in water
Skin is moist and smooth
Breathe through lungs and skin
Lay eggs in water
Cold-blooded animals
Heart has three chambers

Examples

Rana tigrina
Bufo bufo

3) Reptilia

Characteristics

Mostly terrestrial animals
Skin covered with dry scales
Breathe through lungs
Lay shelled eggs on land
Cold-blooded animals
Heart mostly three-chambered (except crocodile)

Examples

Naja naja
Crocodylus palustris

4) Aves (Birds)

Characteristics

Body covered with feathers
Forelimbs modified into wings
Breathe through lungs
Warm-blooded animals
Lay hard-shelled eggs
Heart has four chambers

Examples

Pavo cristatus
Columba livia

5) Mammalia

Characteristics

Body covered with hair or fur
Mammary glands produce milk for young ones
Mostly give birth to young ones
Warm-blooded animals
Breathe through lungs
Heart has four chambers

Examples

Homo sapiens
Elephas maximus

Importance of Animals

Source of food (milk, meat, eggs)
Help in agriculture
Maintain ecological balance
Provide wool, silk, leather

Nomenclature

Nomenclature is the scientific system of naming organisms.
It helps scientists give unique and universal names to plants and animals so that there is no confusion.
The system of scientific naming was introduced by Carl Linnaeus.

Why Nomenclature is Important?

1) Common names of organisms vary from place to place.

2) The same organism may have different local names.

3) Scientific names are universal and accepted worldwide.

Example:

The animal we call human has the scientific name Homo sapiens.

Binomial Nomenclature

The system used for naming organisms is called Binomial Nomenclature.
Bi = two
Nomial = names

- Each organism has two scientific names:

1) Genus name
2) Species name

Example:

Mangifera indica

Here:

Mangifera → Genus
indica → Species

Examples of Scientific Names

Common Name	Scientific Name
Human	Homo sapiens
Mango	Mangifera indica
Lion	Panthera leo

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