class 12 bio chapter 2 ppt by asha gopalakrishna

CHAPTER 2 PPTSEXUAL REPRODUCTION IN

FLOWERING PLANTSPREPARED BY ASHA GOPALAKRISHNA

L.S OF A FLOWER

L.S.OF A FLOWER

Three dimensional cut section of an anther

Anther- T.S young and mature dehisced

T.S of anther young and mature

MicrosporogenesisPMC (2n) MICROSPORE(n)

MEIOSIS

Pollen grain tetrad

POLLEN GRAINS

Stages of microspore maturing into a pollen grain

Pollen grains-rich in nutrients

Diagrammatic view of anatropous ovule

MEGASPOROGENESISMMC(2n) MEGASPORE(n)

MEIOSIS

Megasporogenesis

Differences between microsporogenesis and

megasporogenesisMICROSPOROGENESIS MEGASPOROGENESIS

1. The formation of microspore from pollen mother cell by meiosis

1. The formation of megaspore from megaspore mother cell by meiosis

2. It takes place in anther 2. It takes place in ovule of ovary

3. Four functional microspores are produced.

3. Only one functional megasore is produced.

Embryo sac( FEMALE GAMETOPHYTE)(n)

CHALAZAL END

MICROPYLAR END

(n)

(n)

(n)

(n)

SELF INCOMPATIBILITY TO PREVENT SELF POLLINATION

Entry of pollen tube into an ovule

Chalazal end

Micropylar end

Discharge of gametes into synergids

TRIPLE FUSION (n+n+n)

SYNGAMY

Dicot and monocot embryo

Emasculation-removal of anthers from the flower bud before the dehiscence

of anther

Bagging-covering of emasculated flowers with a bag

False fruits of apple and strawberry

thalamusseed