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!
The Exine Layer
It consists of two layers, inner (nexine) which is continuous and an outer (sexine) the sculptured one. The outer layer has ornamentations comprising rod-like bacula showing terminal expansion which sometimes fuses to form a roof like tectum perforated by micropores. During pollen development, the tapetum releases a mixture called tryphine, consisting of carotenoid lipid droplets and fibrogranular proteins into the thecal cavity. These fibrogranular proteins are enclosed in membrane bound cisternae. In tectate pollen, the released substances of tapetum become incorporated on the surface of pollen grains where cisternae membrane ruptures and protein released through micropores enter the tectum and accumulate in the interspaces of bacula.
Pollenkitt is the pigmented lipid fraction left on the surface of the tectum. Unlike intine, the exine held proteins exhibit only one enzymatic activity. The hydration of pollen is described to be stimulatory in releasing the proteins held in the pollen wall layers. The calculated time taken by the exine held proteins of sporophytic origin to pass out is 30 seconds while the intine of gametophytic origin takes a few minutes. This time difference in the protein release has made it easy to collect both samples separately. In SSI systems therefore the rejection reaction is faster than in GSI system.
(a) What effect does alcohol have on reaction time? (b) What other short-term effects does alcohol have? (c) What long-term effects can result from an exce
What is Plant Tissues explain there types? Vascular plants have separate organs to carry out specialized functions. For instance, leaves function to convert radiant energy to
What are hydrophobic molecules (or hydrophobic molecular regions)? What are hydrophilic molecules? How can they be characterized in relation to their polarity? Hydrophobic mol
Define effect Micronutrients during pregnancy period? The need for many vitamins and minerals is increased during pregnancy. Since energy intake increases, the requirements for
Crustacea The Crustacea show a great morphological diversity of appendages which may be grouped into three categories, cephalic, thoracic and abdominal. Their appendages are c
A cell in G1 of interphase has 12 chromosomes. How many chromosomes and DNA molecules will be found per cell when this original cell progresses to the G2?
What are the physio-chemical properties of vitreous? PHYSIO-CHEMICAL PROPERTIES OF VITREOUS: Vitreous is a clear gel like optically empty structure. Its physio-chemical prop
Q. What treatment should be used for constrictive pericarditis? Medical Treatment 1) Judicious use of diuretics to alleviate systemic congestion. This may be enough in s
Q. What do you understand by Hypelglycemia? Hypelglycemia (abnormally high blood sugar): Maintenance of blood glucose levels within or close to the normal range has been stress
what are fats
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