Note 6 |standard 12|Sexual reproduction in flowering plants| Gynoecium| Megasporangium | notes| NCERT| Biology

Sexual reproduction in flowering plants (New syllabus chapter 1 / old syllabus Chapter 2)

Gynoecium| Megasporangium|reproduction in flowering plants|short notes| NCERT| standard 12| Biology

Note 6

Gynoecium 

> Female reproductive part of flower

> Single portion of it - pistil/carpel

>2 types of Gynoecium

    1) Monocarpellary : flower has single pistil

    2) Multicarpellary : flower has more than one pistil

Syncarpous ovary

Apocarpous ovary

>Multicarpellary can be of 2 types

           (1) Syncarpous : all pistils fused together 

           (2) Apocarpous : all pistils not fused- free

> Pistils has 3 parts

Pistil

-->1) stigma :

----> landing platform for pollen grain

-->2) Style : 

----> elongated slender (slim) beneath stigma

-->3) ovary : 

----> bulged part at the base of pistil

----> inside ovary - ovarian cavity (locule) present

----> inside locule- placenta is present

----> placenta will provide nutrition to the embryo

----> ovules (megasporangia) arise from placenta 

----> plants with one ovule (plants which have one seeded fruit) : wheat, paddy, mango

----> plants with more than one ovule (plants which have fruit with more than one seeds) : papaya, watermelon, orchids

 Megasporangium (ovule) 

Ovule of typical angiosperms

Various parts of ovule (draw the image in your book)

> Funicle : 

--> stalk of ovule 

--> by means of funicle, ovule is attached to placenta

> Hilum : 

--> a region where ovule body attaches with funicle

--> junction between ovule and funicle

> Integuments :

--> protective envelopes (layers) of ovule

--> can be 1 or 2 in number

> Micropyle :

--> a small opening where nucellus is not covered by integuments

> Chalaza : 

--> basal part of ovule

--> seen at the opposite end of micropylar end

> Nucellus :

--> mass of cells inside the integuments

--> these cells have abundant (lots of) reserved food material

> Embryo sac :

--> placed inside the nucellus

--> made up of a megaspore 

--> also called as female gametophyte - because it is haploid and contains female gamete/egg

--> generally one ovule give rise to → one embryo sac → one embryo sac is made up of one megaspore : this is called as monosporic condition 

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Happy learning!

Thank you for reading!

Manish Mevada

Urvi Bhanushali