Important Points Of The Chapter “Sexual Reproduction in Flower | Neet jee
Important Points Of The Chapter “Sexual Reproduction in Flowering Plants”
Flowers are morphological & embryological & embryological structures and the sites of sexual reproduction.
The tapetum (innermost layer) nourishes the developing pollen grains. Cells of the tapetum posses dense cytoplasm and generally have more than one nucleus.
Pollen grain (male gametophyte): Generally spherical. 25-50 mm in diameter. Cytoplasm is surrounded by a plasma membrane.
Exine is made up of sporopollenin (highly resistant organic material).
Intine is a thin and continuous layer made up of cellulose and pectin.
In over 60% of angiosperms, pollen grains are shed at and pectin.
A typical mature angiosperm embryo sac is 8- nucleate and hilum.
Cleistogamous flowers produce assured seed-set even in the absence of pollinators.
Xenogamy brings genetically different types of pollen grains to the stigma.
In sea grasses, female flowers remain submerged in water. Pollen grains are long and ribbon like.
Credits : Mr. Singh
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