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.How is it produced and what is the function of cholecystokin in the digestive process? The fat level of the chyme detected in the duodenum stimulates the secretion of cholecy
The transducer is placed in the mid axillary line with the transducer ridge pointing towards the patients left to obtain the four-chamber view. The left ventricular apex is
What is the difference between an ecological niche and a habitat? An ecological place is a set of peculiar activities, resources and strategies that a species explores to repro
On the overall process of cell-to-cell communication within the nervous system, what role does the Ca2+ play in the synapse? A) contributes in the biosynthesis of acetylcholine B)
Iron deficiency Iron plays an essential role in oxygen transport in the body as a constituent of haemoglobin where nearly 60% of the body iron is found. Apart from oxygen tran
Since erythrocytes red blood cells do not hold any sub cellular organelles they are essentially a membranous sac for carrying haemoglobin their plasma membrane is a convenien
Excretory organs of agama lizard
Discuss why humans not evolve with one central repository of DNA rather than having it replicated throughout the body?
How can the visual deficiencies known as myopia and hypermetropia be optically explained? Myopia is the visual condition in which the images are produced before (in front of)
Q. Common causes related with angina pectoris? • The usual cause of angina is the narrowing of the major coronary artery due to atherosclerosis. • Systemic hypertension inc
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