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.
Q. What is the germ layer from which the coeloms originate? The coeloms are deriving from mesoderm.
Difference between Distant object and Near object - Distan t object Near object 1. Parallel light reaches to eye. 2. Ci
claasification of phylum porifera
Concerning the mixture of arterial with venous blood what is the difference between the human fetal circulation and the adult circulation? In the human fetal circulation there
Q. What is the etiological agent of visceral leishmaniasis? How the disease transmitted and what is are its typical manifestations? The Visceral leishmaniasis is caused by the
Carrier ions like Na+ facilitate the absorption of substances like: 1. amino acids and glucose 2. glucose and fatty acids 3. fatty acids and glycerol 4. fructose and so
who proposed the trinominal nomenclature
Composition of blood: Take few ml. of fresh blood in a test tube and before collecting the blood add a few drops of sodium oxalate or sodium citrate solution to prevent clot
Q. What are neoplasias? The Neoplasia is any abnormal and uncontrolled proliferation of cells of an organism. The Neoplasias can be benign or malign and benign neoplasias are t
Class of Subphylum Uniramia - Pauropoda A small group of uniramians, there are 500 species of Pauropoda explained so far. The minute organisms computing about 1.5 mm in length
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