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

Find initial osmotic pressure on room temperature of a cell, Find the initi...

Find the initial osmotic pressure at room temperature of a cell if the only ions present are CaCl2 on either side of the membrane. Assume the concentrastions for K+ and Cl- from Ta

Three phases into which the hiv infection is often divided, Q. What are the...

Q. What are the three phases into which the HIV infection is often divided? The HIV infection is frequently divided into three phases the acute phase, from the infection to 1 u

Explain precautions for gram staining of bacterial cultures, Explain Precau...

Explain Precautions for Gram Staining of Bacterial Cultures? 1. The dilutions should be chosen on the basis of expected counts in the food sample. 2. Food should be kept in

Popularity of chromatography - basic separation technique, Define Popularit...

Define Popularity of Chromatography - Basic Separation Technique? Chromatography is popular because: (a) minute quantities can be analysed qualitatively and quantitatively,

Sources of pollution, There are two main sources of pollution: (1). Nat...

There are two main sources of pollution: (1). Natural Sources:             (a) Volcanic ash             (b) Marsh gas (CH4) released from decay of organic matter.

Medical and nutritional management for pectic ulcer, Q. Medical and Nutriti...

Q. Medical and Nutritional Management for pectic ulcer? To provide physiological rest and support tissue healing, treatment should be based on providing rest to the affected ar

Mycroboilogy mycoplasma, How we write assimgment about mycobiology of mycop...

How we write assimgment about mycobiology of mycoplasma in detail

What is coronary disease, Q. What is coronary disease? The Coronary dis...

Q. What is coronary disease? The Coronary disease, or the coronary insufficiency, is a disease in which there is total or partial obstruction of one or more of the arteries tha

State cryptobiosis and explain the function of it, State Cryptobiosis and e...

State Cryptobiosis and explain the function of it. A dormant, or suspended, state of animation which allows some animals to survive severe conditions like extremely low tempera

What is different about identical length and centromere, Two chromosomes in...

Two chromosomes in a cell have identical length and centromere position yet are not homologous, what is different about them.

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