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.
Explain Cyanotic Heart Disease breifly? Presence of cyanosis means deoxygenated blood reaching the systemic circulation bypassing the lungs i.e., right to left shunt. Uniform c
Define the Role of Thiamin in the conversion carbohydrate to fats? Thiamin helps in the initial steps of fatty acid and sterol production. In this way, thiamin also helps co
Q. What are the major features of fishes associated to the habitat where they live? Fishes are all aquatic animals and thus they have a hydrodynamic elongated body appropriate
Define Sugars - Chemistry and Functionality? In this section we will learn about the simple carbohydrates called sugars. As you may already know, those carbohydrates that canno
Protection of our property: · If any our property lies in an area prone to landslides, we should seek advice of experts in earth movement and take cor
Explain Total Anomalous pulmonary Venous Connection (TAPVC) ? In this congenital anomaly there is no direct communication between the pulmonary veins and the left atrium. All
How does true motility differ from brownian movement? What morphological structre is responsible for bacteria motility? Why is the wet preparation discarded in disinfectant s
Define the Energy requirement to avoid Underweight problem? The total calorie intake should be 500 to 1000 Kcal in excess of the daily needs in order to result a gain in weight
Keel is characteristic of the flowers of : 1. Gulmohur 2. Cassia 3. Calotropis 4. Bean Bean
Differential centrifugation divides cellular components based on the differences in their size and / or density. A tissue sample was homogenized and three parts (aliquots) of this
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