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

Which pancreatic tissues involved in endocrine secretion, Q. What are the p...

Q. What are the pancreatic tissues involved respectively in the endocrine and exocrine secretions? What are their respective hormones and enzymes? The exocrine secretion of the

Role of biotic factors inducing senescence, Role of Biotic Factors Inducing...

Role of Biotic Factors Inducing Senescence Besides environmental and endogenous factors, biotic factors also play a role in inducing senescence. For example, due to an attack

What is respiratory system explain their functionality , What is Respirator...

What is Respiratory System explain their functionality ? The respiratory system is responsible for the transport of oxygen and carbon dioxide from outside the body to and from

Illustrate about urine of humans, Urine Normal urine is clear, yellow i...

Urine Normal urine is clear, yellow in colour, slightly acidic. Urine consists of 96% water and 4% solids like urea, uric acid, urates, chlorides, phosphates, oxalates, sulphat

Define the effects of deficiency of calcium in the body, Define the effects...

Define the effects of Deficiency of Calcium in the Body? If there is a continued inadequate intake or poor intestinal absorption of calcium, plasma calcium concentrations will

Skeletal muscle need an antagonistic partner, Why does each skeletal muscle...

Why does each skeletal muscle need an antagonistic partner? Because muscles can only contract and relax, each skeletal muscle requires an antagonistic partner to extend it afte

Can you explain hormones, Q. What are hormones? Hormones are substances...

Q. What are hormones? Hormones are substances collected by the circulation and secreted by the endocrine glands that act to produce effects upon specific tissues and organs and

Differences between genomes in prokaryotes and eukaryotes, What are the dif...

What are the differences between genomes in prokaryotes vs. eukaryotes?

Stages of wilms tumour , Stages of Wilm's tumour  We shall now discuss...

Stages of Wilm's tumour  We shall now discuss about the various stages of Wilm's tumour. The extent of  disease is staged according to the findings of  surgery and  the presen

Do protozoans have a cellular nucleus, Q. Do protozoans have a cellular nuc...

Q. Do protozoans have a cellular nucleus? All protozoans, as eukaryotes have nucleus, some species like the paramecium have two nuclei the micronucleus and the macronucleus.

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