Tetrasporic embryo sacs, Biology

Assignment Help:

Tetrasporic Embryo Sacs

In this group neither of the meiotic divisions is accompanied by wall formation so that at the end of meiosis all the four haploid nuclei remain in a common cytoplasm forming what is termed a coenomegaspore. A tetrasporic embryo sac is more heterogeneous than a bisporic embryo sac because the four products of meiosis involved in its formation are genetically different. The nuclear behavior in tetrasporic embryo sacs is quite variable. The arrangement of the four nuclei in the coenomegaspore before the beginning of post-meiotic mitosis is of three types:

(A) 2+2 arrangement; two nuclei at the micropylar ad and two of the chalazal end

 (B) 1+1+1+1 arrangement; one nucleus at the micropylar end, one at the chalazal end, and two placed laterally, one in each side, and

(C) 1+3 arrangement; one nucleus at the micropylar end and three at the chalazal end. Depending on whether nuclear fusion occurs or not, the number of the post-meiotic mitosis in the coenomegaspore and final organisation of the embryo sac, tetrasporic embryo sacs are of many types.


Related Discussions:- Tetrasporic embryo sacs

What is the natural habitat of e.coli, What is the natural habitat of E.col...

What is the natural habitat of E.coli? The E.coli was first recognized in the colon region of large intestine and so it was given the name "coli" (found in colon) they are coli

Explain about food processing and engineering, Explain about Food processin...

Explain about Food processing and engineering? Fundamental engineering concepts like momentum, heat and mass-transport systems; engineering aspects of food processing plant ope

Vapour theory - pre-mendelian theory, V apour Theory (i)         It wa...

V apour Theory (i)         It was proposed by a Greek philosopher Pythagoras in 500 B.C. (ii)         Each organ of an animal body emitted some kind of vapour and that a ne

Explain some guidelines to help in use drugs wisely, Explain some Guideline...

Explain some Guidelines to Help in Use Drugs Wisely? By now, you are aware that the interaction of foods and drugs is a complex problem. Researchers cannot always predict wheth

Mode of nutrition , What is the mode of nutrition in fish,human,amoeba,scor...

What is the mode of nutrition in fish,human,amoeba,scorpian & toad ?

Explain the properties of gum karaya, Explain the Properties gum karaya ...

Explain the Properties gum karaya Gum karaya is water-swellable rather than water-soluble and absorbs water very rapidly to form viscous colloidal dispersions at low concentra

Rhythm and conduction disturbances, Q. Rhythm and conduction disturbances? ...

Q. Rhythm and conduction disturbances? Alterations in cardiac rhythm occur frequently with exercise and are important in understanding a patients function and in providing pred

Intervention strategy, Intervention Strategy There are five basic ways...

Intervention Strategy There are five basic ways in which government can correct market failures and ensure equity: inform, regulate, mandate, finance and deliver health care s

What is the meaning of food exchanges, What is the meaning of Food Exchange...

What is the meaning of Food Exchanges Food exchanges mean grouping of foods in which the specified amount of all the food provides approximately equal amounts of carbohydrate,

Antiarrhythmic therapy, Patients with heart failure have a high incidence o...

Patients with heart failure have a high incidence of both symptomatic and asymptomatic arrhythmias. About 10 per cent of patients have syncope or presyncope resulting from ventr

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd