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

Tautomeric shifts, The original DNA sequence when ,transcribed and translat...

The original DNA sequence when ,transcribed and translated would yield five successive valine residues. But the altered sequence would correspondingly read one aspartate and four s

What are the habits of patients- implants, Habits of patients- Implants ...

Habits of patients- Implants Smoking has been shown to predispose to poor bone quality by reduced vascularity. Therefore it is prudent not to accept heavy smokers as implant pa

Why does the ingestion of vegetable fibers improve the bowel, Why does the ...

Why does the ingestion of vegetable fibers improve the bowel habit in people that suffer from hard stools? Some types of plant fibers are not absorbed by the intestine but play

Drawbacks of nutritional status that assessed traditionally, Define drawbac...

Define drawbacks of Nutritional status that assessed traditionally? Nutritional status assessed traditionally with the use of anthropometric, biochemical clinical and dietary a

Describe the advantages of sulphur, Describe the advantages of sulphur ...

Describe the advantages of sulphur Sulphur also increases the oil content of crops such as flax and soyabeans. Disulphide linkages ( -S-S-) have recently been associated with

Complications during angina pectoris, Q. Complications during angina pector...

Q. Complications during angina pectoris? It is a symptom giving a warning of impending myocardial infarction, sudden cardiac death or even ischemic necrosis of the brain leadin

How are mammals characterized, Q. Mammal identity card. How are mammals cha...

Q. Mammal identity card. How are mammals characterized according to examples of representing beings, skin, respiration, nitrogen waste, basic morphology, circulation, thermal contr

Explain vitamin a deficiency - micronutrient deficiencies, Explain Vitamin ...

Explain Vitamin A Deficiency - Micronutrient Deficiencies? Vitamin A deficiency (VAD) is a major public health problem, and the most vulnerable are preschool children and pregn

Why on earth would be drinking milk to feel better, If a person has a stoma...

If a person has a stomach ulcer (that is aggravated by excessive hydrochloric acid {HCl} secretion ), why on earth would he or she be drinking milk to feel better, when milk is als

Explain some do's and don'ts when working in laboratory, Explain some Do's ...

Explain some Do's and Don'ts when working in Laboratory? 1) Always wear a lab coat when working a laboratory. 2) Ensure that no harm is caused to yourself or the people work

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