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 algae have cell wall, Algae have cell wall made up of: 1. Cellul...

Algae have cell wall made up of: 1. Cellulose, galactans and mannans 2. Hemicellulose, pectins and proteins 3. Pectins, cellulose and proteins 4. Cellulose, hemicellulo

Explain nutrition or diet counseling, Explain Nutrition or diet counseling ...

Explain Nutrition or diet counseling Nutrition or diet counseling  is a  primary educational activity  of  the dietitian.  It incorporates the idea of working with a patient, e

Lactation, LACTATION - Production of milk in the female's breasts af...

LACTATION - Production of milk in the female's breasts after delivery is lactation. Prolactin is responsible to synthesize milk in breast. Oxytocin is responsibleto gi

Neuroglia - organisation of nervous system, Neuroglia - Organisation of Ner...

Neuroglia - Organisation of Nervous System We may refer neuroglia as the connective tissue of the nervous system. It involves all elements of the nervous system other than ne

How to increase the ratio of nadh, Certain conditions such as excessive alc...

Certain conditions such as excessive alcohol consumption can increase the ratio of NADH/NAD+ in the mitochondria. This will directly inhibit which of the following enzymes? -cit

Tagmatization, sample assignment on tagmatization

sample assignment on tagmatization

Structural function - essential elements, Structural Function - Essential E...

Structural Function - Essential Elements The elements nitrogen, phosphorus and sulphur absorbed from the soil are essential components of amino acids and nucleotides. The othe

Define fats requirements of school children and adolescents, Define Fats re...

Define Fats requirements of school children and adolescents? The linoleic acid requirements for school children and adolescents have been set at 3 en%. In terms of visible fats

Explain the uses of isP in cereal products, Explain the Uses of ISO in Cere...

Explain the Uses of ISO in Cereal products  Cereal products  ISP is sometimes used instead of, or in mixture with isolates and soy flour, in the formulation of milk replac

Fluid mosaic model, FLUI D MOSAIC MODEL Proposed by Nicholson and ...

FLUI D MOSAIC MODEL Proposed by Nicholson and Singer (1972) Proteins and lipids are arranged in a mosaic fashion. Lipids and proteins are in a semi fluid structure.

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