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.
Microorganisms Acquired During Transport, Handling and Processing of Raw Foods Microorganisms can come from truck, tanker, food handlers and equipment and utensils used in the
What are the four characteristics that all chordates have at some stage of their lifecycle ?
Diagnostic Procedures Taking Clinical history Urine analysis Blood sample for estimation of blood urea nitrogen Antistrepto lysine (ASO) titer
Determine the Signs and Symptoms of Bulimia? 1. Binges, minimum twice a week for three months 2. Purging a Menstrual irregularities 3. Swollen glands Frequent fluct
????? # 100 ??????????? #Minimum ?????? ?????
Oxidation Some enzymes which have the sulfhydryl (-SH) group in the catalytic site are very sensitive to oxidation. Due to oxidation of the -SH group by aerial oxygen
Why is complementary base pairing important in DNA structure? Complementary base pairing is important because the hydrogen bonds between the bases hold the two strands of DNA
Explain about the Protein-Energy Ratio (NDP Cal%)? Platt and his colleagues (1961) are largely responsible for the introduction of the ratio of protein energy to total energy (
Define method Used for Capsular Staining - Anthony Staining Method? Another method used for capsular staining is Anthony staining method, devised by E.E. Anthony in 1931. The m
Which of the following characteristics is not shared by typical birds and mammals? A) Four chambered heart B) Milk production C) Four limbs D) Endothermy E) Insulating skin structu
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