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

Formation of blastopore, Formation of Blastopore The slit such as ope...

Formation of Blastopore The slit such as opening of the initial groove is the opening of the developing blastopore and its dorsal rim is termed as the dorsal lip of blastopor

Agricultural activities - cause of air pollution, Agricultural activities -...

Agricultural activities - Cause of Air Pollution Agricultural activities too are a major cause of air pollution. About 60 to 65% of carbon dioxide is produced from burning of

Does ph affect the enzyme activity, Does pH affect the enzyme activity? ...

Does pH affect the enzyme activity? The concentration of hydrogen ions in solution affects the enzyme activity. Every enzyme has maximal efficiency under an optimum pH. As p

Write the definition of communication, Q. Write the definition of communica...

Q. Write the definition of communication? Communication is "a process of transmitting ideas, information, attitudes (images which we have formulated for ourselves) by the use o

Explain about non ionising radiation, Q. Explain about Non ionising radiati...

Q. Explain about Non ionising radiation? Non ionising radiation include infrared and UV rays. Lethal effect is through generation of heat and DNA damage. Penetration is low but

Give some examples of cloning and molecular biology, Examples of cloning an...

Examples of cloning and molecular biology cloning may produce heterozygous individuals (as mother was heterozygous) and suggests a way to get pure breeding cats molecu

What is the significance of pharyngeal gill slit, What is the significance ...

What is the significance of Pharyngeal gill slit ? Lateral opening in the wall of the pharynx which allows water to enter into the mouth and exit through the pharynx. This is on

What is the determination of vitamin B2, What is the Determination of vitam...

What is the Determination of vitamin B 2 In the chemical method, the yellow-green fluorescence of aqueous solution of riboflavin is measured. In the microbiological assay, tur

Are gametes always made by meiosis, Q. Are gametes always made by meiosis? ...

Q. Are gametes always made by meiosis? In the haplontic haplobiontic life cycle and in the plant life cycle (diplobiontic life cycle) gametes are made by mitosis and not by mei

Major human viral diseases transmitted by mosquitoes, Q. Are there non vira...

Q. Are there non viral hepatitides? The Hepatitis is a generic name for inflammation of the liver and there are bacterial hepatitides, for instance, in lepstopirosis, and toxic

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