Question

Both gymnosperms and angiosperms bear seeds But,why are they classified separately? 

Answer 1

• Gymnosperms and angiosperms are classified separately because, Ovules in gymnosperms are naked. In angiosperms, they are enclosed inside the ovary. Further Wood is non-porous in gymnosperm, ie., the vessels are absent. Wood in angiosperms is porous. ie., the vessels are present.
• Angiosperms support pollinators to carry out pollination in contrast to gymnosperms. Give reasons. 
• In gymnosperms, pollination is carried out only by wind. 
• Flowers in angiosperms have showy petals, nectaries, scent glands and several other devices toattract the insects, birds and other animals including man to help them to get pollinated.
• A seed enclose three generations one within the others. Justify the statement.
• A seed enclose three generations one within the other: 
• The ovule or megasporangium formed from the parent sporophyte is diploid (2n). 
• An ovule consist of integument and nucleus. Both of them are diploid and belongs to sporophyticgeneration. 
• The megaspores developing within the ovule is formed by meiosis and is haploid(n). The megasporedevelops into haploid female gametophyte which develops an egg (n). 
• This represents haploid(n) gametophytic generation. The egg is then fertilized by a male gamete, toform a diploid (2n) zygote.
• The Zygote then develops into an embryo or future sporophyte (2n).