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

Describe the factors of biological evolution of humans, Although there are ...

Although there are differences in interpretation of the evidence, it is generally accepted that human biological evolution has not been a linear progression from one species to the

The genetic code within a dna molecule, How is a genetic trait determined b...

How is a genetic trait determined by the genetic code within a DNA molecule? A DNA molecule has 4 dissimilar bases, either CGTA. Any specific combination of these things forms

Predation, Think back to the patterns of predator-prey cycling from Section...

Think back to the patterns of predator-prey cycling from Sections 2 and 3. Which of the three predator functional responses would you expect to be most likely to give stable popula

Adults with infective endocarditis, Mitral valve prolapse (MVP) has emerged...

Mitral valve prolapse (MVP) has emerged as a prominent, predisposing structural cardiac abnormality and in adults accounts for 7 to 30 per cent of NVE in cases not related to drug

What are the symptom of short bowel syndrome, Q. What are the Symptom of sh...

Q. What are the Symptom of short bowel syndrome? Diarrhoea is the main symptom of short bowel syndrome. Other symptoms include: • Anorexia • Steatorrhoea • Heart bum a

Reflexes, Reflexes It is used to assess the neurobehavioural status....

Reflexes It is used to assess the neurobehavioural status. Rooting reflex - Being a primitive reflex, if cheek is rubbed, the infant will turn his head into that dire

Explain difference between an ecological niche and a habitat, What is the d...

What is the difference between an ecological niche and a habitat? An ecological place is a set of peculiar activities, resources and strategies that a species explores to repro

Human eye, by our eyes we can see the beautiful world but is there anything...

by our eyes we can see the beautiful world but is there anything in our eyes which makes it beauiful??

What are the phenotypic ratios, Honeybees are unusual in that male bees (dr...

Honeybees are unusual in that male bees (drones) have only one copy of each gene, while female bees have two copies of their genes. That is because drones develop from eggs that ha

What information from the patients symptoms, A 16 year old boy named Jake w...

A 16 year old boy named Jake was admitted into the emergency room complaining of headache, fever, stiffness of abdominal muscles and difficulty swallowing. The doctor on staff bega

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