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!
Colonial Theory - Metazoa
This is the most popular theory on the origin of Metazoa. The idea was conceived by Haeckel (1874) modified by Metschnikoff (1886) and revived by Hyman (1940). This theory considers the flagellates to be the most probable ancestral group of metazoans. For support of this theory the following evidences are cited:
1) Flagellated spermatazoa occur throughout the metazoan series.
2) Monoflagellated cells (with a single flagellum) are also common in lower metazoans (especially among sponges and coelenterates).
3) True sperms and eggs (feature of metazoans) are present in phytoflagellates.
4) Phytoflagellates also display a type of colonial organization that could have led to a multicellular construction. In fact, differentiation between somatic and reproductive cells has been attained in Volvox. Although Volvox is often used as a model for the flagellated colonial ancestor, it is not the likely ancestor of metazoans. Ultrastructural evidence points to the choanoflagellates (a small group of animal like flagellates) as the probable ancestor. Choanoflagellates have mitochondria and flagellar structures very similar to those in metazoan cells. Also choanocytes i.e. cells with a collar of microvilli are found in a number of groups of metazoans notably the sponges.
Biological Significance of Incompatibility Both interspecific and intraspecific incompatibility determines the degree of inbreeding and out breeding of plants. Self-incompati
Shrub Stage - Xerarch Sufficient soil is formed in the herbs stage, for supporting the woody plants or the shrubs. They migrate with the help of seeds or rhizomes from the adj
Q. Do the amine and the carboxyl groups attached to central carbons participate in the union between amino acids? Yes. The nitrogen of the amine group of one amino acid binds t
What is the inactivation of the X chromosome? What is a Barr body? The Inactivation of the X chromosome is a phenomenon that occurs in women. Ever since women have two X chromo
Principles of HACCP A) Determine the Critical Control Points (CCPs) B) Establish Critical Limit(s) C) Establish a System to Monitor Control of the CCP D) Esta
What is Gingival Inflammation Areas of overt inflammation should be identified and the etiology investigated to initiate proper treatment.
Ask quplz heestion #Minimum 100 words acce
What are caloreceptors
adaptation of the phylum protozoa to its function
What is the Mode of Nutrition in mosquito?
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