Nuclear type - endosperm, Biology

Assignment Help:

Nuclear Type - Endosperm

The primary endosperm nucleus divides. The cell wall is not laid. These nuclei and their division products form a large number of free nuclei. The first few divisions are synchronous as a result nuclei are seen in multiples of two i.e. 4, 8, 16, 32 and so on. Later the nuclear divisions are non-synchronous i.e. the nuclei may be seen in different stages of divisions and the number of endosperm nuclei are not in multiples of two. The free nuclei thus formed remain suspended in the cytoplasm of the embryo sac. After some time the nuclei become gradually pushed towards the periphery by an expanding central vacuole.

A large number of nuclei accumulate towards the micropylar and chalazal ends. The nuclei may increase in size either by the fusion of two or more or by their independent growth. The process of cell formation starts with the centripetally growing walls from the periphery proceeding towards the centre of embryo sac or from the apex progressing towards the base. To begin with a single layer of uninucleate cells is formed. Subsequent anticlinal and periclinal divisions of these cells lead to complete cellularization of the endosperm. In some plants only one or two peripheral layer of endosperm cells may develop and the entire embryo sac may remain in the he nuclear state or cell formation may be restricted only to the micropylar end of the embryo sac. In a few plants wall formation may not take place at all and the endosperm has free nuclei. Normally the endosperm cells are only uninucleate; sometimes more than one nucleus may be enclosed within a cell. The number may further increase by nuclear divisions.

The development of endosperm in coconut is interesting. When the fruit is young the embryo sac is filed with a clear fluid containing numerous free endosperm nuclei. Later, the periphery becomes jelly-like, containing several cells. As the fruit matures, and the cellular endosperm along the periphery becomes very massive, the central part contains a sweet liquid with a large number of nuclei. The cellular endosperm constitutes the edible copra rich in stored fat. In the betel nut and fruits of several other palms, the cellular endosperm becomes very hard and woody.


Related Discussions:- Nuclear type - endosperm

Give three examples of artificial selection, Give three examples of artific...

Give three examples of artificial selection. Include examples of both animals and plants.  Answers will vary, but could include domestic cats, domestic dogs, cattle, sheep, an

Wind-environmental components, Wind Strong current of air is known as w...

Wind Strong current of air is known as wind, it is an important ecological factor as it affects plant life mainly on flat plains, along sea coasts and at high altitudes in moun

What is gum arabic, Gum Arabic Gum Arabic or Gum Acacia is the oldest  ...

Gum Arabic Gum Arabic or Gum Acacia is the oldest  and best known of the natural gums. Gum Arabic is the natural exudate produced by various species of the thorny Acacia trees

Blood group, when the father and the mother of a newborn baby possesses blo...

when the father and the mother of a newborn baby possesses blood group ''O'' +ve,is it possible that the baby can have a blood group ''A'' +ve or ''B''+ve ? Conventionally it shoul

Knock-out experiment, Knock-out experiment  is a method for deleting, mutat...

Knock-out experiment  is a method for deleting, mutating or otherwise inactivating the gene in a mouse. This laborious technique involves transfecting a crippled gene into cultured

What are the major natural plant hormones and their effect, What are the ma...

What are the major natural plant hormones and what are their respective effects? The major natural plant hormones and their respective functions are the following- Auxins that

What is the nature of monosaccharides, What is the Nature of Monosaccharide...

What is the Nature of Monosaccharides? Monosaccharides are colourless, crystalline substances which are soluble in water but insoluble in non polar solvents. Monosaccharides ca

Explain theory of enzyme action, Explain Theory of enzyme action L. Mic...

Explain Theory of enzyme action L. Michaelis  and k L. Menten developed a general  theory of enzyme action and kinetics  in  1913. According to this theory, we learnt  that

Indications for surgery-pulmonary regurgitation, Indications for Surgery : ...

Indications for Surgery : Patients usually present with fatigue, dyspnoea and ventricular arrhythmias. If they have additional tricuspid regurgitation, pulmonary valve replacement

#biology tutor title.., When nd how i can srt my online work in this site q...

When nd how i can srt my online work in this site question #Minimum 100 words accepted#

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