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.
Why lymph is also called middle man of body
You have a neuron with a resting potential of -55 mV, EK of -70 mV, and ENa of 50 mV. You decide to voltage clamp the neuron. Now, draw the membrane current over time. What will th
Q What are the few examples of arthropods? Ants, crabs, cockroaches, shrimps, flies, spiders and scorpions are examples of arthropods.
Describe Chemical changes in fruits and vegetables The detailed chemical changes that occur when fruits and vegetables are boiled in water or steamed, canned, dried or frozen,
Equine infectious anaemia Equine infectious anemia (EIA), an acute or chronic viral disease of the equines, shows intermittent fever, loss of weight, depression, progressive w
Triglyceride and cholesterol synthesized in the liver are secreted in very low density lipoprotein (VLDL) particles which serve to transport the lipids to the periphery. VLDL form
Q. What do you mean by Pericardial effusion? Collection of fluid in the pericardial sac is known as Pericardial effusion. All cases of pericarditis can lead to pericardial effu
SHORT COMING OF CELL THEORY / EXCEPTIONS OF CELL THEORY (i) Viruses can be considered as exception to cell theory. They are made of proteins and ones of nucleic acid i.e.
economic importance
Q. Which is the vertebrate class that is considered the first entirely terrestrial? Totally independent from the aquatic habitat, The first entirely terrrestrial vertebrate cla
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: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd