CBSE Class 9 Science Chapter 7 Revision Notes

Chapter 7: Diversity In Living Organisms Revision Notes

INTRODUCTION TO TAXONOMY

Diversity

• The occurrence of different creatures in the same habitat or geographical place is known as diversity.
• Diversity increases the likelihood of a more balanced ecology.

Evolution

• Evolution is the gradual process through which organisms change in response to their demands in order to survive in their environment.
• New organisms emerge as a result of evolution, and the ecosystem becomes more diverse.

Charles Darwin

• Charles Darwin was a naturalist and a biologist from England.
• He visited the Galapagos Islands in South America aboard the HMS Beagle.
• In his book On the Origin of Species, he developed the hypothesis of evolution based on his observations.

Taxonomy

• The science of taxonomy is concerned with the classification of organisms.

HIERARCHY OF TAXONOMY

Classification Hierarchy

• Organisms are classified into groups or tiers based on their similarity.
• As we move up the food chain, the organisms become less similar.

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Kingdom

• A kingdom is the highest level of classification, consisting of a group of related phyla or divisions (in the case of plants).

Phylum/Division

• A phylum/division is a categorization level that consists of several classes with comparable traits.

Class

• A class is a level of classification that includes a group of orders that have comparable qualities.

Order

• An order is a classification level that includes a group of families with comparable traits.

Family

• A family is a level of taxonomy that includes many Genus that have similar traits.

Genus

• A genus is a level of categorization that includes a group of species that share comparable traits.

Species

• A species is a level of classification that includes a group of creatures that have similar traits and may breed to produce fertile offspring.

Nomenclature

Linnaeus Carolus

• Carolus Linnaeus, popularly known as the “Father of Taxonomy,” is a Swedish botanist and physician.
• He established the Binomial nomenclature and established the foundation rules for current taxonomy.

Binomial Nomenclature

• Linnaeus introduced Binomial Nomenclature as a method of naming organisms in taxonomy.
• It is divided into two sections.
• The Genus name, which is printed in capital letters, is the first portion.
• The species name, which is not capitalised, is the second portion.

CLASSIFICATION OF THE 5 KINGDOMS

• R.H.Whittaker’s 5 Kingdom categorization is the most widely acknowledged way of classification.
• This classification resolved the majority of taxonomic difficulties involving the location of bacteria and fungus.
• Monera, Protista, Fungi, Plantae, and Animalia are the five kingdoms.

**Kingdom Monera **

Monera

• This Kingdom is home to all prokaryotic creatures.
• Kingdom Monera is made up of bacteria and archaebacteria, an ancient cousin of bacteria.
• These organisms are prokaryotic, unicellular, and autotrophic/heterotrophic.
• Bacteria have a polysaccharide-based cell wall.

Archea

• The Monera kingdom’s category for species that can survive in extremely hot environments.
• They are said to be the most ancient living organism on the earth.

Eubacteria

• Eubacteria is a Monera phylum that includes any bacteria that can thrive in a normal environment.
• This category include all of the major beneficial and harmful bacteria that we are familiar with today.
• Bacteria of Gram +ve/-ve Gram +ve/-ve Gram +ve/-
• Because some bacteria have a thick cell wall, they absorb Gram stain and appear violet.
• Other bacteria have a thin cell wall and appear pink when stained with Gram stain.
• In most cases, gram +ve bacteria are harmful.

KINGDOM PROTISTA

Protista

Except for yeast, all eukaryotic unicellular organisms belong to the kingdom Protista.

Protozoan

• Protozoans are unicellular eukaryotic organisms that belong to the Protista Kingdom.
• Paramecium, amoeba, Plasmodium, euglena, and leishmania are some examples.
• Protists are fungi, and fungi are fungi.
• Unicellular fungi such as yeast and moulds belong to this kingdom.
• Some photosynthetic unicellular algae belong to the kingdom Protista.

KINGDOM FUNGI

Fungi

• The majority of the species in the Kingdom Fungi are saprophytic.
• It is the only Kingdom in the world that contains both multicellular and unicellular species.
• Chitin makes up the majority of their cell walls.

KINGDOM PLANTAE

Plantae

• This Kingdom encompasses all of the plants and trees that we see around us.
• They’re all autotrophic and have chloroplasts in their cells.
• Cellulose makes up their cell wall.
• Cryptogams and Phanerogams are the two major divisions of the plant kingdom.

Cryptogamae

• Plants having hidden reproductive organs are known as cryptogams.
• Cryptogams are plants that reproduce via spores rather than seeds.
• As a result, there are no flowers or fruits on these plants.
• Thallophytes, bryophytes, and pteridophytes are the three types of cryptogams.

Phanerogamae

• Phanerogams are plants that reproduce by producing seeds.
• Some of them do not bear flowers, while others do.
• Gymnosperms and angiosperms are two types of phanerogams.

Thallophyta

• The first division of the plant kingdom is Thallophyta.
• There are red, green, and brown algae in it.
• They don’t have a lot of structure differentiation.

Bryophyta

• The plant kingdom is divided into two divisions: Bryophyta and Bryophyta.
• These are the first plants that have roots and shoots that are distinct.

Pteridophyta

• Pteridophyta is the plant kingdom’s third division.
• The roots, stem, and leaves of these plants are all distinct.

Gymnosperms

• The word gymnosperm means “bare seed.”
• Because they produce seeds that are not encased in a fruit, they are the first phanerogams.

Angiosperms

• Angiosperm is the last division of the plant kingdom, and it contains the most advanced species on the planet, according to scientists.
• They produce flowers and fruits, which contain the seeds.

Cotyledons

• Cotyledons are structures found in seeds that provide sustenance during germination, when the leaves have not yet formed.
• Angiosperms are classified as dicots or monocots depending on whether they contain two or one cotyledon.

Monocots and Dicots

• Angiosperms, the most advanced plants on the planet, are classed further based on the number of cotyledons in their seeds.
• Seeds with two cotyledons are referred to as dicots.
• Dicots have a reticulate venation and a tap root system. Mango, pea, beans, and other fruits and vegetables are examples.
• Monocotyledons are seeds with only one cotyledon.
• Monocots have a fibrous root system with venation that runs parallel to each other.
• All grains, such as wheat, maize, and rice, are examples.

KINGDOM ANIMALIA

Animalia

• Eukaryotic, multicellular, heterotrophic creatures make comprise the kingdom Animalia.
• They are either herbivores or carnivores, and their mode of sustenance is holozoic.
• The majority of animals are mobile, meaning they can move around on their own in search of food, shelter, or a mate.
• Animals are made up of a variety of organ systems that work together to accomplish certain duties that are essential for the organism’s existence.
• The majority of animals are bilaterally symmetrical, with the exception of early species, which are asymmetrical, and cnidarians and echinoderms, which are radially symmetrical.

Porifera

• The sponges belong to this phylum.
• They are largely marine, with only a few freshwater species.
• The creatures are all sessile (fixed in one place).
• The cells are placed in a haphazard manner (cellular grade of the organization).
• The outer ectoderm and inner endoderm of animals are held together by the jelly-like mesoglea.
• Exoskeleton in the form of silica or calcium carbonate spicules.
• Pores can be found all over the body of sponges. Ostia refers to the pores on the body.
• Water enters the body through the Ostia and exits through the osculum, a single big aperture.

Coelenterata

• These are generally marine species that live in water.
• They can be solitary or colony in nature. Each individual is referred to as a zooid.
• Animals have a radial symmetry.
• Polyps are sessile creatures, while Medusa are free-living forms.
• Tissues are made up of cells (tissue grade of the organization).
• Diploblastic animals have outer ectoderm and interior endoderm. These two levels are separated by Mesogloea.
• The hypostome is a single hole in the body surrounded by sensory tentacles.
• The coelenteron is a body cavity (coelom) that serves as a gastrovascular cavity.
• Nematocysts, a type of cell found in tentacles, are responsible for capturing and paralysing pray.
• Hydra, jellyfish, corals, obelia, and sea-anemone are other examples.

Platyhelminthes

• Bilaterally symmetrical, triploblastic, and flattened organisms make up this phylum.
• The organization’s organ-system grade is visible.
• The outer ectoderm, middle mesoderm, and inner endoderm of animals are all triploblastic.
• There is no bodily cavity in an acoelomate.
• The digestive system is deficient or non-existent.
• The majority are parasites, although a few are free-living.
• Liver fluke and tapeworm are two examples.

Nemotoda

• The bodies of these animals are symmetrical on both sides, triploblastic, and cylindrical.
• The organization’s organ system grade is visible.
• There is Pseudocoelom present.
• Have a digestive system that is tubular in shape and has openings on both ends.
• They’re parasitic endoparasites.
• Hooks and suckers are provided in the mouth.
• Ascaris, hookworm, filarial worm, and other parasitic worms are examples.

Annelida

• These organisms are triploblastic and exhibit bilateral symmetry.
• They are generally aquatic, with only a few exceptions.
• These organisms are the first to have a genuine coelom.
• Intersegmental septa divide the coelome into sections.
• The body is lengthy and segmented metamerically (segmentation from outside and inside of the body).
• Leech, earthworm, and other examples

Arthropoda

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• With 80 percent of all known living animals, this is the largest phylum.
• Animals with appendages that can be joined (in Greek Arthron: jointed, poda: legs).
• The head, thorax, and abdomen are the three segments/regions of the body.
• An exoskeleton formed of chitin protects the body.
• They have an open circulatory system and are bilaterally symmetrical.
• There are compound eyes present.
• Insects, scorpions, spiders, millipedes, centipedes, crabs, lobsters, and other animals are examples.

Mollusca

• They are symmetrical on both sides, with a small coelomic cavity and little segmentation.
• They have an open circulatory system and excretion organs that resemble kidneys.
• The body is delicate and usually has a shell around it. It is possible for the shell to be external or internal.
• They show that the Foot, Mantle, and Mantle Cavity are all present.
• Pearl oysters, bivalves, sepia, octopus, snails, slugs, and other organisms are examples.

Echinodermata

• They have a spiky skin and live entirely in the sea.
• Typically, the animals are pentamerous.
• They have a coelomic cavity and are triploblastic.
• They move forward using a water-driven tube system.
• Starfish, sea urchins, sea cucumbers, sea lilies, and other sea creatures are examples.

Hemichordates

• Hemichordata is triploblastic and bilaterally symmetrical.
• A notochord, which runs along the back of the animal and separates the nerve tissue from the intestine, is also present.
• They are saltwater organisms that serve as a link between non-chordates and chordates.
• Non-chordates/invertebrates range from Porifera to Echinodermata.
• Balanoglossus, popularly known as the acorn worm, is an example.

Chordata/Vertebrata

• A dorsal, tubular, hollow nerve cord is present.
• Notochord is present.
• Slits in the pharyngeal gills are present.
• There is a post-anal tail present.
• Body that is symmetrical on both sides.
• Three germ layers are present.
• Organization at the organ-system level.
• The ventral heart and hepatic portal system are present.
• Endocrine glands that are fully matured
• The vertebral column replaces the notochord in all animals except a few primitive types. Vertebrates are the name given to these creatures.

Pisces

• All bony and cartilaginous fishes are classified as Pisces.
• They are only found in water.
• With paired and unpaired fins, the body is streamlined.
• These are vertebrates with a cold blood supply.
• The heart has two chambers.
• The system of lateral lines is substantially established.
• Sharks, rays, Rohu, Mrigal, green carp, and other species are examples.

Amphibia

• Amphibians can live on land and in water, and they lay their eggs in the latter.
• In the larval stage, breathing is done through the gills, while in the adult stage, breathing is done through the lungs.
• They’re cold-blooded creatures.
• They have a heart with three chambers.
• Frogs, toads, salamanders, and other amphibians are examples.

Reptilia

• These are the first animals that are entirely land-based.
• Cold-blooded reptiles breathe through their lungs.
• They lay eggs with tough covers and have a three-chambered heart (excluding crocodile).
• Scales, scutes, or hard plates cover the body.
• Snakes, crocodiles, turtles, lizards, and other reptiles are examples.

Aves

• This category includes all birds.
• They have a four-chambered heart and breathe through their lungs and are warm-blooded.
• Their forelimbs have been transformed into wings to aid in flight.
• Jaws have been transformed into beaks.
• Bones are hollow, with the majority of them fused together to reduce body weight.
• Feathers are used as an exoskeleton.

Mammalia

• They have a four-chambered heart and are warm-blooded. They breathe through their lungs.
• Mammalian characteristics include the presence of hair on their bodies, as well as perspiration and oil glands.
• Only mammals have an external ear, which is known as a pinna.
• They also have mammary glands, which they use to nourish their young.
• Typically, they give birth to live young.
• Humans, cattle, and other animals are examples.

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