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 pineal gland? The pineal gland also known as epiphysis or pineal body is situated centrally in the head. It secretes the hormone melatonin. A hormone produced at
Define Class Turbellaria - Flatworms ? Members of these two Classes are known as the flukes. Flukes are parasitic flatworms that inhabit tropical areas like Southeast Asia and
The various types and their description of Heart failure are as follows: Left Sided Versus Right Sided Heart Failure Predominantly left sided failure is seen in left ventr
Describe the regulation of pyruvate dehydrogenase through covalent modification. PDH exists in 2 forms : Inactive, phosphorylated and Active, dephosphorylated. The active form
Define Recommended Dietary Allowance for Folate (RDA)? Folate requirements are the intake levels necessary to prevent deficiency with clinical symptoms. The requirements are ex
Q. Are there diverse proteins made by the same total number of amino acids? Diverse proteins with the same total number of amino acids may exist. In such cases the discriminati
G a ngrenous dermatitis (necrotic dermatitis) A bacterial condition in chickens caused by spores of Clostridium septicum , sometimes that of Cl. novyi / Cl. edematiens a
Enumerate different implant materials with their pros and cons Biomaterials fall into four categories: metal and metal alloys, ceramics (carbon included in this group) syntheti
How do homeotic genes regulate development in Drosophila? Homeotic genes code for regulatory proteins that are thought to control the rate of cell division in various body area
Each of the three eukaryotic RNA polymerases has more subunits or 12 and so these are big complex enzymes. The genes encoding some of the subunits of each eukaryotic enzyme show
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