Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Release of Microspores
Up to the tetrad stage, there is no cellulosic wall around the microspores. As you will come to know in the next unit, a unique feature of the pollen is the ornamentation of the pollen wall. This ornamentation is seen on the outer layer of the pollen or exine. The exine is made up of sporopollenin, one of the most resistant (to physical and biological decomposition) substances known in the biological world. Pollen grains of prehistoric plants are well preserved as fossils because of their exine. There is enormous variation in the ornamentation of the exine, and it is a characteristic feature of a given species. Often pollen grains of particular group of plants can be identified on the basis of their exine pattern.
The blue print of exine, termed primexine is laid down below the callose wall after the basic structural features of the exine including the position of the germ pore (a region in the pollen wall through which the pollen tube emerges) are demarcated in the primexine. This important morphogenetic event takes place while the microspores are still enclosed in the callose wall, in groups of four or at the tetrad stage. Thus, the pattern of mature exine is laid down before the spores are set free. The callose wall seems to play an important role in the orderly deposition of primexine. You will read more about this in the next unit. After the development of exine, the callose wall dissolves. The enzyme callase which dissolves the callose wall is produced by the surrounding tapetal cell pen plasmodium. The development of the male gametophyte begins after the liberation of individual microspores.
WHAT ARE TYPES OF EGG
Binomial Nomenclature The modern system of classification (Binomial nomenclature) accepted by biologists today was proposed in 1758 by the Swedish botanist Linnaeus (1707-1778
D-glucose differs from D-galactose only in the arrangement around carbon 4. Therefore D-glucose and D-galactose are- Select one: a. enantiomers b. epimers c. mirror ima
Ask quesIn Cross 1, pure-breeding colored, starchy kernel plants (C1Wx/C1Wx) were crossed to plants pure-breeding for colorless, waxy kernels (c1 wx/c1 wx). The F1 of this cross we
Define isolated soybean proteins in Cereal products? ISP is sometimes used instead of, or in combination with isolates and soy flour, in the formulation of milk replacer mixtur
The pancreas produces insulin, a hormone that is specifically produced in the beta cells of the pancreas and it is responsible for the regulation of blood glucose. After carefull c
The highest possible magnification that can obtain when using using a microscope?
Modern Biology Increasing advancement in biotechnology has brought about a veritable explosion of Biological knowledge since early 1950s.This vast modern biological information
Define Role of Iron in Controlling Gene Expression? Iron metabolism is regulated by a complex co-ordinate mechanism. Recent evidence supports specific past-transcriptional mech
Effect on Microbial Growth and Ecology Redox potential exerts an important selective effect on the microflora of a food since it will decide the type of microorganism that can
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd