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

Transport with the help of membrane protein, Transport with the Help of Mem...

Transport with the Help of Membrane Protein Even though, the lipid bilayers do not permit the entry of polar molecules such as ions, sugars, amino acids, nucleotides and cell

What is the result of post myocardial infarction ventricular, What is the r...

What is the result of Post Myocardial Infarction Ventricular ? Results: Hospital mortality may be as high as 30 per cent. This depends on the extent of infarction and- pre-op

Explain the chemotherapeautic rinses, Explain the Chemotherapeautic rinses ...

Explain the Chemotherapeautic rinses Chemotherapeautic rinses:  The use of  0.12  per cent chlorhexidine has been proven to be of therapeutic significance in maintaining period

What is the function of the skin in humans, Q What is the function of the s...

Q What is the function of the skin in humans? The skin is the external covering of the body. In humans its major functions are protection and perception of information from the

What is echocardiography, Q. What is Echocardiography? Ans. Echoca...

Q. What is Echocardiography? Ans. Echocardiography has become an established and powerful tool for diagnosing presence of CAD and defining its consequence. It can help in

What are the frequencies of dominant and recessive allele, In a population ...

In a population of 200, 90 are homozygous dominant, 40 are heterozygotes, and 70 are homozygous recessive for a particular trait. What do you expect the frequencies of the dominant

Explain disorders of the gastrointestinal tract, Q. Explain Disorders of th...

Q. Explain Disorders of the gastrointestinal tract? The diseases and disorders of the gastrointestinal (GI) tract. Have you ever suffered from abnormal symptoms of the gastroin

Explain the determination of hydrolysis, Explain the Determination of Hydro...

Explain the Determination of Hydrolysis Hydrolysis of calcium pantothenate in acidic medium produces  α,γ-dihydroxy-β,β-dimethylbutyrolactone, which reacts with hydroxylamine i

Do echinoderms present external or internal fecundation, Q. Do echinoderms ...

Q. Do echinoderms present external or internal fecundation? Is there sex division among individuals? The fecundation in echinoderms is external, gametes are liberated in water

What is embryogenesis explain in detail, What is Embryogenesis explain in d...

What is Embryogenesis explain in detail? Embryogenesis in humans consists of the first eight weeks of development of the zygote. Embryogenesis in animals is generally divided i

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