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.
Dot blot is the technique for measuring the amount of one perticular DNA or RNA in the highly complex mixture. The samples are spotted onto the hybridization membrane (like nitroc
At the beginning of the process in an animal cell, the partition of the centriole takes place, which has been duplicated during Interphase but were in the same centrosome. Bipol
What is the significance of Axial skeleton? The bones which make up skeleton of the main body axis of vertebrates. It comprise the cranium, vertebral column, and rib cages, How
Q. Can you explain Irradiation? Irradiation: It is the process of exposing food to carefully controlled amount of ionising energy to destroy and control microorga
Q. What are instances of nematodes? Ascaris, filaria and hookworm, all parasites of humans, are instance of nematodes also known as roundworms. Q. Are nematodes exclusively
Define Changes associated with the skeletal system - Ageing? Skeletal bone loss occurs with ageing and may have serious consequences among the elderly. With ageing, there is so
Explain Adverse Effects Fluconazole is generally well tolerated. Gastrointestinal distress and rash can happen. Stevens-Johnson syndrome, anaphylaxis and hepatic necrosis have
How are gases exchanged in sponges? The gas exchange in sponges occurs by diffusion from the external to the cells that absorb molecular oxygen and release carbon dioxide.
Which are the glands present in the epidermis of mammals, birds and reptiles? In the epidermis of birds and reptiles there are almost no glands. In mammals there are sweat glan
Determine Balanced Diet For Celiac Disease? Energy: initially the children are seen to be malnourished, thus 100-120 Kcal/kg body weight/day with gradual increase to 150 Kcal
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: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd