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

Explain about bone lining cells, Explain about Bone lining cells Bone ...

Explain about Bone lining cells Bone lining cells are basically inactive osteoblasts (in terms of making bone) that line bone surfaces. Osteocytes are osteoblasts that have be

Dietetic foods for diabetes, Dietetic Foods for diabetes: With advances...

Dietetic Foods for diabetes: With advances in food technology, foods for special use by diabetics are now available in the global market, they are emerging in India also. These

What is eutrophication in ecology explain briefly, What is Eutrophication i...

What is Eutrophication in ecology explain briefly? Freshwater ecosystems demonstrate the close relationship between aquatic and terrestrial ecosystems. Until recently, most peo

How the required weight gain calculated, How the Required weight gain Calcu...

How the Required weight gain Calculated? Weight gain is another aspect deserving attention. 'Allowable' or recommended weight gain could be higher than for adults. The weight g

Basic concepts of earthquake resistant structures, The aim of earthquake-re...

The aim of earthquake-resistant structure designing The main objectives of earthquake resistant structures are as follows: (i)     To avoid loss of lives due to the destruct

Define important points while working with autoclave, Define Important Poin...

Define Important Points While Working With Autoclave? Note: Following points should be kept in mind while working with autoclave. 1. Autoclave should not be packed tightly o

Define about yersiniosis, Define about Yersiniosis In the genus Yersini...

Define about Yersiniosis In the genus Yersinia, 11 species are recognized, including Y. pestis, the cause of plague. The species of primary interest in foods is Y. enterolytica

Does the trend of the change in shape of the graph, Does the trend of the c...

Does the trend of the change in shape of the graph as temperature increases differ when a different gas is examined?

Importance of intestinal bacterial synthesis - vitamin k, Define Importance...

Define Importance of Intestinal Bacterial Synthesis as a Source of Vitamin K? Intestinal microflora synthesizes large amounts of menaquinones, which are potentially available a

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