Recurrent type, Biology

Assignment Help:

Recurrent Type

In this type, euspory (seen in normal cases) is replaced by aneuspory (Diplospory) because of irregular meiosis. When the spore mother ceIl functions directly as the embryo sac initial it is termed gonial apospory and when one or more of the somatic cells of the nucellus or chalaza act as embryo sac initial it is called somatic apospory.

Aneuspory (Diplospory)

Includes cases in which during spore formation the meiotic process is irregular. Depending upon the extent of irregularity in meiosis in various plants, aneuspory is further categorized into various types.

  • Datura type - the two unreduced nuclei undergo two mitotic divisions to produce an 8-nucleate embryo sac.
  • Taraxacum type - first meiotic division ends in a restitution nucleus. Meiosis II produces unreduced cells. Ultimately an 8-nucleate embryo sac is formed. The egg directly forms the embryo.
  • Ixeris type - it is like Taraxacum, but a single binucleate gynophore is formed. Two divisions lead to the formation of an 8-nucleate embryo sac.
  • Allium type - a premeiotic-endomitotic doubling makes meiotic prophase to start with double chromosome number. The result is an unreduced embryo sac.

Related Discussions:- Recurrent type

What is the diffusion, Q What is the diffusion? Diffusion is the spread...

Q What is the diffusion? Diffusion is the spreading of substance molecules from a region where the substance is further more concentrated to another region where it is less con

Cells, #question.why are active cells small .

#question.why are active cells small .

Define theory for check the presence of rhodamine b, Define Theory for Chec...

Define Theory for Check the Presence of Rhodamine B? Addition of artificial colours to pulses, spices and tea is not permitted by PFA act. But certain colours, which contain le

Classification scheme of protozoa, Classification Scheme of Protozoa ...

Classification Scheme of Protozoa Phylum Myxozoa Parasites of lower vertebrates especially fish and invertebrates. Phylum Microspora Parasites of inv

Red flowers is crossed with a white-flowered plant, A plant with red flower...

A plant with red flowers is crossed with a white-flowered plant of the similar species. All the seeds, when grown, produce plants with red flowers. Assuming that the flower colour

Transpiration the only way through which leaves lose water, Is the transpir...

Is the transpiration the only way through which leaves lose water? The Plants don't only lose water as vapor as by transpiration. Leaves also lose liquid water by a phenomenon

What physical fitness tests examine, What Physical fitness tests examine? ...

What Physical fitness tests examine? Physical fitness tests examine the components of physical fitness such as endurance, speed, strength, flexibility and body composition. The

.Botany, 57. While planning for an artificial hybridisation programme invol...

57. While planning for an artificial hybridisation programme involving dioecious plants, which of the following steps will be irrelevant A usting of pollen on stigma B Collection

How hiv infection is mainly spread, It is mostly spread by sexual contact, ...

It is mostly spread by sexual contact, blood transfers and from HIV infected mother to child.

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