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 has caused evolution, What has caused evolution? 1) Different indi...

What has caused evolution? 1) Different individuals have dissimilar characteristics 2) These differences result in altering abilities to reproduce under local circumstances

What is coronary artery disease, Q. What is Coronary artery disease? Nu...

Q. What is Coronary artery disease? Nutrition is a basic prerequisite for maintaining a desirable body weight and that diet has a major role in the prevention and treatment of

Explain administrative dietitian, Explain Administrative dietitian Admi...

Explain Administrative dietitian Administrative dietitian play  a  major  role in  large-scale meal planning  and monitoring the  food  preparation process  by  applying  the

Explain the concepts of brain development, Explain the concepts of brain de...

Explain the concepts of brain development Two concepts that are especially critical to understanding brain development in the very young child are: Symbolic representati

What is st elevation in leads without q-wave, Q. What is ST Elevation in Le...

Q. What is ST Elevation in Leads without Q-Wave? ST elevation in leads without Q-waves can occur in few very different situations, both of which are fairly uncommon. The first

Difference between rough and smooth endoplasmic reticulum, Q. What is the d...

Q. What is the difference between rough and smooth endoplasmic reticulum? The endoplasmic reticulum is a delicate membranous structure contiguous to the nuclear membrane as wel

Genomic dna from the sea urchin, Eric Davidson isolated and compared the se...

Eric Davidson isolated and compared the sequences of mRNA transcripts and genomic DNA from the sea urchin. Which of the following is a true statement regarding his findings? A.

Gene recombinations, Which of the recombination process(transformation, con...

Which of the recombination process(transformation, conjugation and transduction) would be most likely to occur in the natural environment?

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