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.
STIMULENT S - It makes a person more wakeful, alert and active. (i) Caffeine ( C 8 H 10 N 4 O 2 ) - It is 1,3,7-trimethylxanthine obtained from tea leaves ( Thea si
Define Half Saturation Test and Full Saturation Test? This test is specific to polysaccharides. The test is used to detect dextrin from starch. The details related to the test
Describe Valvular PS Murmur and their characterstics? Characteristic: Harsh crescendo-decrescendo murmur along the left sternal border and loudest at pulmonary area, conducted
ime day 0 day 1 day 3 day 4 day 5 day 7 count blank 7 10 5 14 9 8 low 45&49 64&70 62&69 75&79 80&82 68&72
What else is carried in the plasma? In addition to proteins, plasma having salts (ions), glucose, lipids and amino acids, hormones, carbon dioxide and urea
Respiratory Gases -Respiration Physiologically the most important gases are oxygen, carbon dioxide and nitrogen. Molecular oxygen comprises 21% of the atmosphere; carbon diox
phylogenetic consideration
charaacteristics
Signify the term - Pectoral girdle. Bones in vertebrates that connect the appendages on the left and right side of the anterior appendicular skeleton to each other. Pectoral gi
What is Computerised tomography Computerised tomography (CT, but also known as computerised axial tomography, or CAT) provides structural images. To generate brain scans, low l
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