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 effect of fat on quality and quantity of human milk, Define effect o...

Define effect of Fat on quality and quantity of human milk? Fat content of milk appears to be subject to variability as compared to other constituents. The average fat content

Shrub stage - xerarch, Shrub Stage - Xerarch Sufficient soil is formed...

Shrub Stage - Xerarch Sufficient soil is formed in the herbs stage, for supporting the woody plants or the shrubs. They migrate with the help of seeds or rhizomes from the adj

What volume of 19 m formic acid need in experiment, You are interested in u...

You are interested in using formic acid (pKa = 3.75) as a buffer for your biochemical Experiment. a) Would it be most useful for creating a buffered solution at pH 2, 4 or 6? Ex

What are the main types of waste, What are the main types of waste? The...

What are the main types of waste? The waste can be classified into main types, each of them carrying its own dissimilar environmental problem: organic waste, non recyclable was

Tolerance range - ecosystem, Tolerance Range - Ecosystem Organisms are...

Tolerance Range - Ecosystem Organisms are able to survive only within certain maximum and minimum limits with respect to each environmental factor such as water, light and tem

Define the protective of vitamin c role as an antioxidant, Define the Prote...

Define the Protective of Vitamin C role as an antioxidant? Vitamin C is a powerful antioxidant because it can donate a hydrogen atom and form a relatively stable ascorbyl free

Why is it rare to find hemophilic women, Why is it rare to find hemophilic ...

Why is it rare to find hemophilic women? There are less hemophilic women than hemophilic men because women need to have two X chromosomes affected to develop the disease while

How does the cd4 counting act to monitor the hiv infection, Q. How does the...

Q. How does the CD4 counting act to monitor the HIV infection? What is another laboratory method to follow up the disease? The CD4 counting test is complete from a blood sample

Determine the importance of behavioural observations, Determine the importa...

Determine the importance of Behavioural observations Behavioural observations are often noteworthy to the extent that they involve alterations in the examiner's usual response

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