Chapter 7: Diversity In Living Organisms Revision Notes
INTRODUCTION TO TAXONOMY
- 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 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 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.
- The science of taxonomy is concerned with the classification of organisms.
HIERARCHY OF TAXONOMY
- Organisms are classified into groups or tiers based on their similarity.
- As we move up the food chain, the organisms become less similar.
- A kingdom is the highest level of classification, consisting of a group of related phyla or divisions (in the case of plants).
- A phylum/division is a categorization level that consists of several classes with comparable traits.
- A class is a level of classification that includes a group of orders that have comparable qualities.
- An order is a classification level that includes a group of families with comparable traits.
- A family is a level of taxonomy that includes many Genus that have similar traits.
- A genus is a level of categorization that includes a group of species that share comparable traits.
- A species is a level of classification that includes a group of creatures that have similar traits and may breed to produce fertile offspring.
- 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.
- 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 **
- 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.
- 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 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.
Except for yeast, all eukaryotic unicellular organisms belong to the kingdom Protista.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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 is the plant kingdom’s third division.
- The roots, stem, and leaves of these plants are all distinct.
- The word gymnosperm means “bare seed.”
- Because they produce seeds that are not encased in a fruit, they are the first phanerogams.
- 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 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.