Download 9. organ of multiplication---seed ，fruit 1. experimental principle

9.
fruit
organ of multiplication---seed
multiplication---seed，fruit
1. experimental principle:
seed is the common organ of multiplication between gymnosper m and
angiosper m,however fruit is typica l organ of multiplicating organ of angiosper m.
Fertilized ovum starts to clea vage after a while of dorma ncy and then forms proembryo
with two corpusculars,the big one of which is basal cell ,locating on micropylar end and
the sma ll one locating on chala zal end is top cell.The top cell continues to develop and
then fina lly forms mature embryo from globular embryo to torpedo-shape embryo. Basal
cell takes part in development of embryo,and in the same time, endosper m is developed
through polar nucleus which is formed by polar nucleus ’s fertilizing. Embr yo and
endosper m are two most important parts of seed.The fruit is formed by intumeescing of
oophoron ， and the seed is formed from ovule.The ture fruit is formed from
oophoron,however the false fruit is formed not only from oophoron but also from the
parts outside of oophoron.The simple fruit is formed from a single flower,a nd the
aggregate fruits are formed from poly-pistil,a nd the collective fruit is formed from
inflorescence. Otherwise the fruit is categor ize into ma ny types by pericarpia l
shape,structure of oophoron,a nd the type of placenta.
2. experimental objectives
1)、To master the development process of embr yo of dicotyledon
2)、To master the ground form and basic development process of seed and fruit.
Article for experimental use
3、Article
1) 、 Materia ls : perma nent longitudina l sction of of pickpurse’s embr yo in ever y
development phase. And various kinds of seed and fruit.
2) 、 Instrumenttation: microscope, ma gnifying glass, cover glass, microscope slide;;
dissecting knife; dissecting needle.
Method and procedure;
4、Method
1．The stucture and shape of the seed:
（ 1 ） double seed lea f -exa lbuminous seed:obser ve the immersed seed of broad
bean,which is consisted of seed coat and embryo
（2）double seed lea f -albuminous seed: observe the immersed seed of castor bean,which
is consisted of seed coat , embr yo and endosper m.
（3）single seed lea f -albuminous seed:obser ve the cinetic seed of corn, and its embr yo is
located on the segmental venter which looks like a white heart.And then longitudina lly
cut the seed,you will see the thin film ,formed from fruit coat and seed coat, on the
longitudina l section .With a drop of iodize,there are severa l parts of longitudina l section
with different colors,a nd the pullous part is endosperm,the other part is embr yo which is
consisted of seed lea f, plumule, radicle and embryona l axis.
2．The development of the embr yo and endosper m
Observe the ovule ¡ªspecia lly about integument , endosper m, embr yo
suspensor,through the perma nent longitudina l sction of shepherd's purse’s oophoron
and
¢Ù proembryo phase ： proembryo is in free nucleus phase and locates around embr yo
sac,which has a sap vesicle in centre.
¢Ú
Differentiated embr yo phase: heart-shape embr yo and torpedo-shape embr yo phase
③mature embr yo phase: embryonic pla nt grows and differentiates seed lea f and radicle . e
3 ．The stucture and shape of the fruit.
Fruit is formed through pollina tion and fertilization of flowers,which leads pistil to be
withered or residual,a nd leads ovary wall to accrete. The skin of fruit can be divided into
three la yers--- exocarp, mesocarp and endocarp.
4 ．the types of fruit: observe in or outside of the door.
debate
5、debate
1．How dose the embr yo develop?how dose it looks like?
2．How do the fruit and the seed develop?
3．How to discr imina te the collective fruit and the aggrega te fruits;?