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 paediatric clinical literature, What is paediatric clinical literat...

What is paediatric clinical literature The paediatric clinical literature has expanded greatly in its coverage of the wide variety of medical circumstances that can negatively

Define uses isolated soybean proteins, Define uses isolated soybean protein...

Define uses isolated soybean proteins? Partially hydrolysed soy proteins possess good foam stabilization properties and can be used as whipping agents in combination with egg a

Explain oral feeding, Oral Feeding This is the preferred and most palat...

Oral Feeding This is the preferred and most palatable method of feeding for meeting the increased nutritional demands of catabolism, it  should be  used as long as possible. If

Preparation for hospitalization of child - nursing, Preparation for Hospita...

Preparation for Hospitalization   Prevention is a strong component of nursing care. Preparation prior to hospitalization is  essential to make the transition from home to hospi

Question 1, Which type of reproductive structure has a better chance of sur...

Which type of reproductive structure has a better chance of survival if there was a sudden temperature change in its environment? A.)asci B.)zygosporangium C.)basidium D.)lichen

What is posterior aneurysm? , What is  Posterior Aneurysm? The te...

What is  Posterior Aneurysm? The technique of Posterior Aneurysm operation is the same. Care must be taken to avoid injury to the posterior papillary muscle and poster

Explain metabolic response to injury, Explain Metabolic Response to Injury?...

Explain Metabolic Response to Injury? There is an increase in the basal metabolic rate above the normal. The degree of hyper metabolism is related to the severity of the injury

Aba - dormancy, ABA - Dormancy Abscisic acid functions as an antagonis...

ABA - Dormancy Abscisic acid functions as an antagonist of all three promoters like IAA, GAS and Cytokinins. ABA nullifies the activity of GA, IAA and cytokinin right by a)

Name the corrosion resistant metals, Name the corrosion resistant metals ...

Name the corrosion resistant metals Most of the corrosion resistant metals or alloys used for implants have a layer of oxides on their surface. The thin (approximately 5 nm) la

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