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

Define herbals - old books about plants, Define Herbals - Old books about P...

Define Herbals - Old books about Plants? During the Middle Ages, following the decline of the Greek and Roman civilisations, little significant botanical progress was made. The

Transcription factors have multiple domains, In most cases, the transcripti...

In most cases, the transcription factors in eukaryotes which bind to promoter   or enhancer sequences   are activator   proteins   which induce   transcription.   That proteins gen

#title. Zoology, Can you give me an explanation on the osmoregulation of th...

Can you give me an explanation on the osmoregulation of the Phyla Cnidaria, Ctenophora, Porifera and the Protozoa?

Hazard analysis, Hazard Analysis Two steps recognized as preliminary a...

Hazard Analysis Two steps recognized as preliminary and detailed analysis of hazard are taken. Preliminary Hazard Analysis (PHA) serves two aims: (i) It can expedite bringi

Fragmentation and regeneration, Fragmentation and Regeneration Both t...

Fragmentation and Regeneration Both the situations mentioned above that is whether occurring naturally or accidentally, can in general, be categorized like fragmentation. Of

Define the management of obesity, Define the Management of Obesity? Man...

Define the Management of Obesity? Management of obesity should be taken up with a clear understanding of the harsh realities of the problem and its outcome. It may be a frustra

Assignment, Structure and development of leaf

Structure and development of leaf

What is the gross primary production of an ecosystem, What is the gross pri...

What is the gross primary production of an ecosystem? How does GPP relate to photosynthesis? Gross primary production of an ecosystem, or GPP, is the amount of organic material

Oreopithecus, Oreopithecus, a late rniocene primate had very close resembla...

Oreopithecus, a late rniocene primate had very close resemblances to those of gibbons, although the tooth structure showed that the animal was only a monkey and not a hominoid. Ano

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