Sterility in angiosperms, Biology

Assignment Help:

Sterility in Angiosperms

Sterility in angiosperms may arise due to several causes. Either the anther may not be formed, or anthers are formed but meiosis may be abnormal.

A. In situations where anthers are not formed, they may take abortive forms and appear like petals or sepals. These conditions are referred to as petaloid and phyllody respectively. There are even cases where anther formation may be suppressed altogether. These cases of pollen sterility have premeiotic determination.

B. There are other examples in which anthers are produced but meiosis is abnormal resulting in the formation of non-viable pollen.

C. Sometimes normal pollen grains are formed but they are not released. This results from failure of anther dehiscence. Such a situation is also described by the term contabiscent anther.

D. Sometimes meiosis is normal but abortion can take place due to premature dissolution of callose. This can occur at any stage during microsporogenesis.


Related Discussions:- Sterility in angiosperms

Meningocele, Meningocele In this the meninges protrude through the op...

Meningocele In this the meninges protrude through the opening in the vertebrae generally in the lower back. The sac contains meninges and cerebrospinal fluid. The sac may

Qualitative changes, Qualitative Changes The qualitative changes in th...

Qualitative Changes The qualitative changes in the structure of proteins in response to stress can lead to the following: Resistance against denaturation of prote

What an enzyme is called, The substance that is worked on by an enzyme is c...

The substance that is worked on by an enzyme is called: a. product b. coenzyme c. substrate d. inhibitor

Explain the alterations occurring in meat and poultry, Alterations occurrin...

Alterations occurring in meat and poultry Meat, as you already know, is  rich in proteins and contains most of the essential amino acids.  It is also rich in minerals such as c

Define the concept of health - public nutrition, Define the Concept of Heal...

Define the Concept of Health - Public Nutrition? The most widely accepted definition of health is the one given by WHO (1948) in the preamble to its constitution, Box 1 gives t

Apomixis, Apomixis The formation of sporophyte from the gametophyte w...

Apomixis The formation of sporophyte from the gametophyte without sexual process signifies apomixis. It relates to the replacement of alternation of a reduced gametophyte and

What is the rh factor, What is the Rh factor? The RH factor is a protei...

What is the Rh factor? The RH factor is a protein of the red blood cell plasma membrane that behaves as antigen in blood transfusions triggering a humoral (antibody-based) immu

Steroids, STEROID S - These are derived lipids. Cholesterol is m...

STEROID S - These are derived lipids. Cholesterol is must in formation of steroid hormones. In steroids cyclopentanoperhydrophenentherene nucleus ring present. S

Explain about the vacuum evaporators, Explain about the Vacuum Evaporators?...

Explain about the Vacuum Evaporators? It is common to construct various vacuumised vessels in series that is why the product moves from one vacuum chamber to the next and thus

Define the sleep disorder - effect of obesity, Define the Sleep disorder - ...

Define the Sleep disorder - Effect of Obesity? One of the common problems that obese males and females suffer from is sleep disorder, commonly known as sleep apnoea. Obesity ca

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