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.
A biologist examines a series of cells and counts 140 cells in interphase, 10 cells in metaphase, 4 cells in anaphase and 7 cells in telophase. if complete cell cycle requires 24 h
Explain cytological approach in taxonomy.
Define Preterm and Low Birth Weight? The foetal and neonatal health is mainly dependent on the birth weight and it has been well recognized that perinatal (from birth upto one
Define Miscibility in binary liquid systems? When two different pure liquids are unable to mix in all proportions, they are said to be partially miscible. When these liquids ar
Thorax and Lungs: The lungs, a pair of conical-shaped organs lie in the thoracic cavity, protected by the bony thorax composed of the sternum and ribs a interiorly and r
STATE THE ECONOMIC AND ECOLOGICAL IMPORTANCE OF ECHINODERMS
heating a food sample with Benedict''s solution is a test for...
What is the phellogen? What its function? The Phellogen also called as cork cambium is the meristematic plant tissue responsible for the formation of the periderm (the covering
Define Swollen and Tender Joints and haemorrhage in various Tissues? Haemorrhages occur deep in muscle, particularly in calf, thigh, buttocks and forearm, causing pain in surro
Q What are the kinds of digestion and of digestive system of platyhelminthes? Flatworms have incomplete digestive systems and they present intracellular and extracellular compl
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