Question Bank [2022] — BIOLOGY STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYQuestion Bank [2022]2 Marks
Question
Describe the structure of pollen grain.
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Answer
The process of formation of microspores from diploid microspore mother cell through meiotic cell division inside the microsporangia or pollen sacs is called microsporogenesis.
Structure of microspore: Pollen grain/microspore is a non-motile, haploid, unicellular body with a single nucleus. It is surrounded by a two-layered wall called sporoderm. The outer wall is called exine and the inner wall is called intine.
Exine: The exine is thick and made up of a complex, non-biodegradable, substance called sporopollenin and it is resistant to chemicals. It may be smooth or with a sculptured pattern (characteristic of the species). At some places, exine is very thin showing thin areas known as germ pores. Germ-pores are meant for the growth of emerging pollen tubes during the germination of the pollen grain.
Intine: The inner wall layer, intine consists of cellulose and pectin.
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