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

Explain isolated chloroplast thylakoids, In an experiment, isolated chlorop...

In an experiment, isolated chloroplast thylakoids were incubated at pH 4.0 with ADP and inorganic phosphate (Pi) added to the medium and then transferred to a medium having pH 8.0.

Why do leaves change color, Why do leaves change color? Leave is the fo...

Why do leaves change color? Leave is the food factories of plants. During the spring and summer, leaves are actively making food and they are filled with chlorophyll, which giv

Explain about the niacin (nicotinic acid) deficiency, Explain about the Nia...

Explain about the Niacin (nicotinic acid) deficiency? Niacin (nicotinic acid) deficiency classically results in pellagva, which is a chronic wasting disease associated with a c

Explain the assessing and monitoring of peri-implant, Explain the assessing...

Explain the assessing and monitoring of peri-implant The parameters used for assessing and monitoring the peri-implant conditions need to be understood and applied judiciously

How would contrast single covalent bonds, 1. In modern blimps, the gas of c...

1. In modern blimps, the gas of choice used to inflate them is helium rather than hydrogen. Hydrogen would be lighter, but helium is safer. Compare and contrast the atomic structur

Why physical fitness is tested, Why Physical Fitness is Tested? 1) To a...

Why Physical Fitness is Tested? 1) To assess pre-training fitness status: Before beginning an exercise programme and allow the exercise, intensity and duration to be set at th

Sequence of cardiac activation, Sequence of Cardiac Activation Depolar...

Sequence of Cardiac Activation Depolarisation is initiated by an impulse form the SA node. Impulse spreads through both atria. Inter-atrial conduction and atrial myocardial

Explain factors that alter the speed of enzymatic recations, What are the m...

What are the main factors that alter the speed of enzymatic reactions? The major factors that change the speed of enzymatic reactions are temperature, pH and substrate concentr

Non-striated or smooth muscles, NONSTRIATED (= SMOOTH) MUSCLES - Non...

NONSTRIATED (= SMOOTH) MUSCLES - Non-striated muscles are found in the posterior part of oesophagus, stomach, intestine, lungs, urinogenital tract, urinary bladder, blood ve

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