The document summarizes key concepts about the evolution of animal diversity. It describes the major splits in animal evolution including acoelomates vs coelomates, radiates vs bilateria, and protosomes vs deuterosomes. The Cambrian explosion occurred around 500 million years ago, resulting in the emergence of modern animal phyla. Today's animals can be classified into over 35 phyla based on their adult forms, embryological development, body symmetry, and presence of tissues and body cavities. Examples of major phyla include sponges, cnidarians, flatworms, arthropods, mollusks, and chordates.
Origin and Evolution of Life by Ratnodip SahaRatnodip Saha
Here I've discussed, how life originated on earth and how it evolved to today's form.
Contents:
What is life? What is life cycle?
Abiogenesis or Origin of life: chemogeny & biogeny
Steps of Abiogenesis
What is Hot dilute soup theory?
Protocells: coacervates & microspheres
What is evolution?
What is variation?
Differences between variation and Mutation
Origin and Evolution of Life by Ratnodip SahaRatnodip Saha
Here I've discussed, how life originated on earth and how it evolved to today's form.
Contents:
What is life? What is life cycle?
Abiogenesis or Origin of life: chemogeny & biogeny
Steps of Abiogenesis
What is Hot dilute soup theory?
Protocells: coacervates & microspheres
What is evolution?
What is variation?
Differences between variation and Mutation
Classifying Life
The Three Domains of Life
Bacteria
Archaea
Protists
Plants
Moving Water Up a Tree
Fungi
Animals
How Birds Fly
Viruses and Prions
Science and Society: Swine Flu
Briefly discuss five criteria used to classify an organism as a multi.pdfMALASADHNANI
Briefly discuss five criteria used to classify an organism as a multicelled animal?
Solution
Organisms that consist of more than one cell are known as multicellular organisms. Multicelluar
organisms are made up of more than one cell. These cells identify and attach to each other to
form a multicellular organism. Most of the multicellular organisms are visible to the naked eye.
Organisms like plants, animals, and some algae from a single cell and they grow up into a
multicelled organism. Both prokaryotes and eukaryotes show multicellularity. True multicellular
organisms regenerate a whole organism from germ cells.
There are there theories to discuss the mechanisms by which multicellularity could have evolved.
Symbiotic Theory- Symbiotic theory states that the first multicellular organism arose from
symbiosis behaviour of different species of a single-celled organism, each performing different
functions. Such symbiotic relation ship is seen between clown fish and Riterri sea anemones.
The Cellularization Theory or The Syncytial Theory- The cellularization theory states a
unicellular organismwould have developed from membrane boundaries/partitions around each
nuclei from a single celled organisms with multiple nuclei. Protists like cliates and slime molds
have multiple nuclei supporting this theory.
The Colonial Theory- The colonial theory that the symbiosis of many organisms of the same
species led to the evolution of multicellular organisms. This theory was proposed by Haecked in
1874.Majority of multicellularity occurs as a consequence of the cells falling to separate
following the process of division. Example of this theory can be seen in multicellular protists like
Volvox, Eudorina.
Advantages of Multicellularity in organism are that multicellularity allows the organism to
exceed the size limits. Multicelluarity also permits in increasing the complexity of the organism
by allowing differentiation of numerous cellular lineages in an organism.
Animals are multicellular and move with the aid of cilia, flagella, or muscular organs based on
contractile proteins. They have organelles including a nucleus, but no chliorplasts or cell walls.
Animals acquire nutrients by ingestion.
They have multiple cell with mitochondria and they depend on other organisms for food
Biologists recognize 36 phyla in the animals kingdom.
Size-The size of animals ranges from a few celled organosm like the mesozoans to animals
weighing many tones like the blue whale.
Animals bodies- Bodies of animals are made of cells organized into tissues which perform
specific functions in most animals tissue are organized into complex organs, which form organ
systems.
Cell structure_ The animal cell contains organelles like the nucleus, mitochondria, Golgi
complex, ribosomes, endoplasmic reticulum, lysosomes, vacuoles, centrioles, cytoskeieton.
Animals are made up of many organs systems, that aids in performing specific functions that are
necessary for the survival of the organism.
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