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!
Female Gametophyte
The development of a female gametophyte is initiated with the enlargement of one of the megaspores (usually the one close to the chalaza in a linear tetrad) followed by three mitotic divisions. Thus, the female gametophyte, also called the embryo sac is almost always a 7-celled or 8-nucleate structure. The eight nuclei thus formed organize into the egg apparatus, central cell with two polar nuclei and three antipodal cells. This mode of embryo sac development occurs in the majority of flowering plants.
There are variations from this mode of female gametophyte development. In order to visualize these deviations let us recall the formation of megaspore tetrad. Out of the four megaspores, three degenerate and only one participates in the formation of embryo sac. This mode of development of female gametophyte is known as the monosporic type. In some plants, two megaspores out of four participate. For example, if after meiosis, the lower or the upper dyad produces the embryo sac and the other degenerates, the development is termed bisporic. Sometimes, cell plate formation does not occur after any of the meiotic divisions and all the four megaspore nuclei contribute to embryo sac formation. 'This is called tetrasporic type of development. Depending upon the orientation and subsequent behavior of the megaspore nuclei and their derivatives, the tetrasporic gametophyte may be of several types.
Vertical Implant Position: The implant can be submerged in the bone up till the level, where it is surface treated or further embedded till its shoulder, depending upon the sit
Tolerance Model - Models of Succession In this model, the presence of early successional species is not essential, that is, any species can start succession. Some species are
Maintenance Therapy A complete remission implies a clinical, haematological and bone marrow remission. For remission therapy drugs like, methotrexate cyclophospharnide and 6-
Food-borne zoonoses Food-borne illnesses are serious public health problem. They are associated with the ingestion of contaminated foods by microorganisms and their toxins, ma
Calvin cycle electron transport chain glycolysis Kreb's cycle photosystem II.
1.sarcomastigophora 2.sporozoa 3.cnidospora 4.ciliophora
Explain Nutrient Requirement and Dietary Management? You must have understood by the discussion above that by the end of the flow phase, the patient usually is well hydrated an
Which of the following best describes the reasons why the sliding clamp is able to confer processivity on DNA polymerase and not DNA primase? A. The sliding clamp coats the tem
How do respiratory pigments act? Respiratory pigments are oxygen-carrying molecules present in the blood. When the oxygen concentration is high, for instance, in the pulmonary
what is the process called free radicals damage body molecules
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