Origin and evolution of metazoa, Biology

Assignment Help:

Origin and Evolution of Metazoa

Most of the early metazoans were soft bodied and so their fossils are rare. The extremely fragmented fossil record does not shed any specific light on their origin. Therefore, 'most of the explanations on their origin are based on their embryology and -comparative morphology. A series of theories have been put forward to explain the origin of multicellular metazoans from unicellular organisms. Of these, three principal theories could be considered.

1) Syncytial Theory: That the ancestral metazoans have arisen from a multinucleate. ciliate by compartmentalization or cellularization.

2) Colonial Theory: That the ancestral metazoans have arisen from colonial flagellates by cellular specialisation and interdependency.

3) Polyphyletic Theory: That the metazoans have arisen from more than one group of organisms.


Related Discussions:- Origin and evolution of metazoa

Determine the physiological effects phytoestrogens, Determine the Physiolog...

Determine the Physiological Effects phytoestrogens? Little is known about the biologic and physiologic effect of phytoestrogens in humans. Animal studies suggest the following

What is the benefit of alternative splicing, Question 1: What is the be...

Question 1: What is the benefit of alternative splicing? Could there also be drawbacks of Alternative splicing? If yes, mention the same. Definitions of alternative splic

425, #questionThree actographs (look closely to see the labels A, B, and C)...

#questionThree actographs (look closely to see the labels A, B, and C). Assume that the abscissa is either 24 or 48 hours for each actograph. You are asked to write two sentences f

What organisms make glycogen, What organisms make starch? What is it used f...

What organisms make starch? What is it used for? What organisms make glycogen? What is it used for?

Explain the uses of isp in meat products, Explain the Uses of ISP in meat p...

Explain the Uses of ISP in meat products Meat products  The main application of ISP in connection with meat and related products is based on the use of texturized ISP, in

Kinds of ovules, Kinds of Ovules Ovules undergo varied degrees of cur...

Kinds of Ovules Ovules undergo varied degrees of curvature during development. The position of micropyle with respect to the funiculus becomes different and constitutes the b

Show the process of cell-to-cell communication, On the overall process of c...

On the overall process of cell-to-cell communication within the nervous system, what role does the Ca2+ play in the synapse? A) contributes in the biosynthesis of acetylcholine B)

Define mechanism for copper absorption, Define Mechanism for Copper Absorpt...

Define Mechanism for Copper Absorption? As in the case of other minerals, copper absorption appears to occur by two mechanisms: i) Saturable active mechanism, which operates

Explain about g-protein, Explain about G-protein   A.  When an agonist ...

Explain about G-protein   A.  When an agonist binds to the binding site of a G-protein-coupled receptor (GPCR), this leads to GTP displacing a GDP bound to the alpha subunit of

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd