Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Syncytial Theory - Metazoa
This theory suggests that the ancestral metazoan was at ,first Syncytial in structure but later became cellularised by formation of cell membranes around individual nuclei this producing a typical multicellular body. Hadzi (1953) and Hanson (1977) have been the chief proponents of this theory. As many ciliates tend to have a bilateral symmetry, the advocates of this theory maintain that the ancestral metazoan was bilaterally symmetrical similar to the present day acoelous flatworms. The theory receives support from the fact that acoelous flatworms are
Figure: Possible routes for evolution of animals
There are several objections to this theory. It ignores the embryology of flatworms in which nothing similar to cellularization occurs, nor does it explain the presence of flagellated sperms in metazoans. Perhaps the most important objection to this theory is that it assumes that .acoelous flatworms are the most primitive metazoans and therefore, presumes bilateral symmetry to be more primitive than radial symmetry and thus radial coelenterates must have been derived from bilateral flatworms. But then it is accepted that radial symmetry is more primitive than bilateral symmetry and radial coelentrates could not have evolved from flatworms.
Explain about the Phosphorus - Macro Minerals? Phosphorus is the second most abundant element in the human body, comprising 30% of the total mineral content. An adult human bod
Which of the following serves as a sensor, or as part of a sensor, that functions in a negative feedback system? A. CaSRs (Calcium-Sensing Receptors) located in the plasma memb
Explain Food lipids It is either consumed in the form of "visible" fats, which have been separated from the original plant or animal sources, such as vegetable oil and butter,
what year was homo erectus fossils found
What is the approximate pH of the salivary secretion? Is it an acid or basic fluid? What are the main functions of saliva? The saliva pH is approximately 6.8. It is therefore a
give data
Advantages of Fertilizers and manures Fertilizers and manures are necessary for maintaining the soil in a high state of fertility and productivity. It is important to know the
Members belonging to different species refrain from mating because of the behavioural differences between them. Such behavioural differences usually centre around specific courtshi
what are the phylum of kingdom protozoan
Name the four organisms which are currently in danger of extinction because of human activities?
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd