Stamen, Microsporangium and Pollen Grain Flashcards
constituents of stamen
long and slender stalk called filament and bilobed anther.
what is the proximal end of the filament connected to
thalamus
an anther is
bilobed and dithecous
what separates the thecas
a longitudinal groove
how many microsporangia in each lobe
2 in each(total 4)
the microsporangia develop further into
pollen sacs containing pollen grains
structure of microsporangia
epidermis, endothecium, middle layers and tapetum
what do the first three layers of microsporangia do
protect the anther and aid in the dehiscence of the anther to release the pollen.
Function of tapetum
to nourish the developing pollen grains
how do tapetal cells become bi-nucleate
no cytokinesis after karyokinesis
what is at the center of each microsporangium
sporogenous tissue
How are microspore tetrads formed
from meiotic division of sporogenous tissue
What is microsporogenesis
formation of microspores from PMC(pollen mother cell)
outer layer of a pollen grain- name and what is it made of
exine and it is made of sporopollenin
why is sporopollenin known as the most resistant organic material
it can withstand high temperatures, strong acids and alkali. no enzyme has been discovered that can degrade sporopollenin.
where is sporopollenin absent in the exine
germ pores
function of germ pores
formation of pollen tube and helps in release of male gamete
inner wall of a pollen grain and what is it made of
intine and it is made of cellulose and pectin
what is formed when a pollen grain matures
a vegetative cell which is a large cell that has abundant food reserve. and a generative cell which floats in the cytoplasm and divides mitotically to form 2 male gametes.
what cause pollen allergy in india
parthenium or carrot grass
when do pollen grains lose their viability in rice and wheat
within 30 mins
when do leguminoseae, Solanoceae and Rosaceae pollen grains lose their viability
within months
at what temperature are pollen grains stored and in what
-196C in liquid nitrogen
