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.
The article entitled "Life on Earth" is trying to make the point that RNA likely included before DNA. Forthis article which of the following is false? A. Chains of RNA nucleoti
Q. Define Maxillofacial Prosthodontics? Dental implants are now been increasingly used for Maxillofacial Prosthodontics. Maxillofacial Prosthodontics involves the prosthetic re
what is reproductive system? what is urinary System? What is Nervous system
Which one of the following statements about human sperm is correct? 1. Acrosome has a conical pointed structure used for piercing and penetrating the egg, resulting in fertilis
Feeding on Liquids Animals feeding on liquids are generally highly specialised for their feeding habits. Certain protozoa, endoparasites and aquatic invertebrates take up nut
Define Nutritional Support Management for pancreatic cancer? When there is deficiency of exocrine pancreatic secretions, adequate amounts of pancreatic extract are helpful. It
Bone Remodeling Bone remodeling differs from the other means of bone structure alteration in that osteoblasts and Osteoclasts do not act independently but are coupled and bone
C h oice of transgenic animal First and foremost is the selection of animal species in which gene of interest is to be transferred. Whatever is the goal of production of tran
Q. Describe Explicit and Semantic Memory? Explicit memory: This is the conscious recollection of information such as specific facts or events and at least in humans that can be
explanation of examples of protozoa
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