Gonial apospory and somatic apospory, Biology

Assignment Help:

Gonial Apospory and Somatic Apospory

Gonial Apospory

There is no meiosis. The megaspore mother cell enlarges; a small vacuole appears above and below the nucleus. The cell thus becomes 1-nucleate embryo sac. Three successive mitotic divisions result into an 8-nucleate embryo sac. In Brachycome, the polar nuclei function directly as the first 2 endosperm nuclei.

Somatic Apospory

Meiosis is apparently normal but megaspores play no part in the embryo sac formation. Either during or soon after meiosis one or more sporophytic cells (nucellar or chalazal) enlarge and invade the nucellar lobe destroying and replacing the megaspore. After 3 successive nuclear divisions each such cell becomes differentiated into an aposporic 2n embryo sac with normal organization. Thus, gametophytic generation is completely eliminated.


Related Discussions:- Gonial apospory and somatic apospory

How mineral salts participate in osmotic regulation, Q. How mineral salts p...

Q. How mineral salts participate in osmotic regulation? Osmotic pressure depends not on the nature of such particles and on the number of particles dissolved in a solution. Min

Define vitamins b12 deficiency in vegans, Define Vitamins B 12 Deficiency ...

Define Vitamins B 12 Deficiency in Vegans? Because plants do not synthesize vitamin B 12 , individuals who consume diets completely free of animal products (vegan diets) are a

Assessment of megaloblastic anaemia, Assessment   On observation of a c...

Assessment   On observation of a child with this type of anaemia you will find that in addition to the symptoms  of iron deficiency anaemia there is hyper-pigmentation over knu

Describe two differences among green algae and red algae, Some biologists p...

Some biologists prefer to categorize brown, red, and some green algae as plants rather than protists. What characteristics of these algae support like classification? Brown and

Management of symptomatic patients, Q. Management of Symptomatic Patients ...

Q. Management of Symptomatic Patients All symptomatic patients with severe aortic stenosis or even moderately severe aortic stenosis should undergo aortic valve replacement an

Taxonomy, A In taxonomy, what is a "KEY" ? List the different types of key...

A In taxonomy, what is a "KEY" ? List the different types of keys. How are they prepared and what are they used for ?sk question #Minimum 100 words accepted#

Loss of biological diversity nowadays, Q. What are the main causes of the l...

Q. What are the main causes of the loss of biological diversity nowadays? The largest dangers to the biological diversity today are the action of humans. The major of them is t

How does the Cornea work, How does the Cornea work, I heard that it is like...

How does the Cornea work, I heard that it is like a motor, however i''m not too sure... because a motor is in vehicle and has piston, and the Cornea is in our eyes and... Well does

Physiology of the heart, The heart is the muscular pump that pushes blood t...

The heart is the muscular pump that pushes blood through the circulatory system. Each heartbeat can be felt as an arterial pulse. The heart valves when closed prevent the blood fro

Opiate narcotics - psychological drug dependence, OPI A T E NARCOTICS - ...

OPI A T E NARCOTICS - They suppress brain activity and relieve pain popularly known as pain killers. They are sedative and astringent in nature. An astringent cause

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