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

What is the essential concepts of endosseous healing, Essential Concepts of...

Essential Concepts of Endosseous healing 1) Osteoblast is the prime bone matrix synthesizing cell. Like most secretory cells, osteoblasts are polarized cells, and the direction

Explain food applications of pullulan, Explain Food Applications of pullula...

Explain Food Applications of pullulan The food applications of pullulan include:  Due to its oxygen barrier properties, it can be used as a packaging material for fat /

What is the most likely genotype of p1, In cats, curled ears (Cu) results f...

In cats, curled ears (Cu) results from an allele that is dominant over an allele for normal ears (cu). Black colour results from an independently assorting allele (G) that is domin

Veterbrate, Draw and describe the structure of amphibian,reptile mammal and...

Draw and describe the structure of amphibian,reptile mammal and bird

Explain anatomy of leaves of four specimens, A student while studying the a...

A student while studying the anatomy of leaves of four specimens (P - S), observed the following characters: P.  Reticulate venation and no bundle sheath. Q. Parallel venati

Phylum Coelenterata, What are the classes in Phylum coelenterata?

What are the classes in Phylum coelenterata?

Define etiology and clinical features of alzheimer''s disease, Define the E...

Define the Etiology and Clinical Features of alzheimer's disease? The probable risk factors include a genetic basis, head injury, low education level, Down syndrome and mother

Explain bruce protocol, Q. Explain Bruce Protocol? Bicycle Ergometry ...

Q. Explain Bruce Protocol? Bicycle Ergometry Most bicycle test are performed sitting upright, but supine bicycle test have become more popular. Treadmill Test The

Cleavage, what are the chemical changes during cleavage

what are the chemical changes during cleavage

Maintenance in the continuing care cycle, Maintenance in the Continuing Car...

Maintenance in the Continuing Care Cycle Impaired dexterity: Any impairment of dexterity, even if it is temporary, may be detrimental to dental implants because home maintena

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