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

Proteins of animal origin - egg, Proteins of Animal Origin - Egg Eggs: ...

Proteins of Animal Origin - Egg Eggs:  Roughly, the chicken egg consists of 11% shell, 31% yolk and 58% white. Liquid whole egg consists of 65% white and 35% yolk. The primary

Protozoa, disadvantages of protozoa in points

disadvantages of protozoa in points

Write down all the four quantum numbers of the electron, Write down all the...

Write down all the four quantum numbers of the electron in the outermost shell of rubidium (At. no.= 37) atom. a) What type of hybridization is associated with N in NH 3 ? b

Exstrophy of the bladder, Exstrophy of the Bladder This is the most c...

Exstrophy of the Bladder This is the most common major congenital defect of lower urinary and genital tract. This is found more frequently in males than in females. Exstr

Criteria for diagnosis of respiratory failure, Criteria for Diagnosis of Re...

Criteria for Diagnosis of Respiratory Failure PaO 2 , PaCO 2 , > 50 mm Hg.  Vital Capacity Respiration > 30/min or below 8/min.

Determine how many family full-time family doctors, 1.  In the town of Jasp...

1.  In the town of Jasper, CA, there is currently one full-time family doctor. If the town's population grows at a steady rate of 14% per year, how many family full-time family doc

Procedures for diagnosis - nucleic acid hybridization, Nucleic acid hybridi...

Nucleic acid hybridization: This is a process by which a suitably labeled DNA or RNA from a known infectious agent is used to probe its complementary sequence unique to t

Determine the maximum crop yield, Determine the maximum crop yield In ...

Determine the maximum crop yield In determining maximum crop yield it was thought that a given plant let us say corn, is only inherently capable of producing a given amount of

What are the two reproductive novelties of beings, Compared to amphibians w...

Compared to amphibians what are the two reproductive novelties of beings of the class Reptilia for the survival in dry environments? Compared to amphibians the two major reprod

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