A fertilized ovule undergoes the following changes in the ovary in an angiosperm plant:
Unfertilized ovule \(\rightarrow \) Fertilized ovule \(\rightarrow \)Seed
Funiculus   \(\rightarrow \) Present
Hilunf  \(\rightarrow \) Present
Integument  \(\rightarrow \) Seed coat
Outer integument \(\rightarrow \) Testa
Inner integument \(\rightarrow \) Tegmen
Chalaza \(\rightarrow \) Present
Micropyle \(\rightarrow \) Present
Nucellus \(\rightarrow \) Absent or present as perisperm
Embryo Sac:
Antipodal cells \(\rightarrow \)  Degenerate
Synergid cells \(\rightarrow \) Degenerate
Secondary nucleus \(\rightarrow \) Endosperm
Egg \(\rightarrow \) Embryo
When the unfertilized ovule undergoes double fertilization, it makes fertilized ovule and then seeds. In this process funiculus and hilum are present. Outer integument makes testa and inner integument is tegmen. Chalaza and micropyle are present but nucellus is absent, partly persish. as perisperm.
In embryo sac antipodals and synergids degenerate. The central cell makes endosperm, and the egg changes into embryo.

(i)No,it was not a wise decision.
(ii) Insecticides kill the insects.These insects are very important for plants as many of these are helpful in carrying out pollination which is very essential for fertilization and seed formation in sexually reproducing species.
(iii)No,many insecticides pollute and, being non-biodegradable, have harmful effects on living organisms

Differences between Simple, Aggregate and Composite Fruits

Structure of microspore (Pollen grain):
Pollen grain develop from the diploid microspore mother cells in pollen sacs of anthers.Typically pollen grain is a haploid, unicellular body with a single nucleus.
The pollen grain represents male gametophyte. The term sporoderm is usually used to designate collectively the two major wall layers-
(i) the exine,  which is the outer layer and chiefly composed of sporopollenin (an organic polymer that is resistant to oxidation and leaching), and
(ii) the intine,  which is the inner layer and chiefly composed of pecto-cellulose.
The exine is differentiated into two layers. The inner endoexine and outer tectum. The exine surface of pollen grains often bear various patterns of microsculpturing and ornamentation. At one or more places, the exine is very thin or absent. These regions are called apertures or germ pores through which the pollen tube emerges at the time of germination on stigma.
The germ pores lack sporopollenin. The protoplasm of pollen grain is surrounded by plasma membrane.
In a mature pollen grain two cells are present, vegetative cell and generative cell. Vegetative cells has abundant food reserve. Generative cell divides and form two male gametes during the growth of pollen tube.

Development of endosperm. Endosperm develops after double fertilization in angiosperms. It is triploid and develops from primary endosperm nucleus. In angiosperms three types of endosperm development are observed:
(1) Nuclear endosperm. In nuclear endosperm development nucleus divides by free nuclear division, there is appearance of central vacuole, all the nuclei are pushed towards periphery then starts cytokinesis and results into the formation of cells hut in coconut vacuole persists which is filled with fluid.
(2) Cellular endosperm. In cellular endosperm each and every division is followed by cytokinesis, so endosperm is cellular from the very beginning e.g. Datura, Petunia.

(3) Helobial endosperm. It is intermediate between cellular and nuclear endosperm. The first division is followed by cytokinesis to form two unequal cells, micropylar cell and chalazal cell. Further divisions in each cell are free nuclear divisions. This type of endosperm is found in order Helobiales.

Contrivances for cross pollination
1. Dicliny
It is formation of unisexual flowers. Statements and carpels occur in different plants. The diclinous plant may be monoecious or dioecious. In monoecious plants, the two types of flower \((\underset { + }{ O } \quad and\quad { O }^{ \nearrow })\) are located in the same plant (e.g., Cucurbita) and in 'dioecious plants, \(({ O }^{ \nearrow }\quad and\quad \underset { + }{ O } )\) flowers are present in different plants, e.g., Carcia papaya.
2. Dichogamy
A condition where male and female sex organs mature at different times. It can be of two types :  protandry where anthers mature earlier than the gynoecium, (e.g.,  Helianthus annus, tagetes, cotton, lady's finger, etc.) and protogyny where gynoecium matures earlier than the anthers,(e.g., Michelia champaca, Brassia, Ficus, Mirabilis, etc.
3. Heterostyly (Hetero = different)
Occurrence of styles and statements of different lengths as heterostyly. Based on this, flowers may have two (dimorphic) or three (trimorphic) forms of anthers and stigmas at different levels. One form has short stamen and long style (pineyed) and the other has long stamens and short style (thrum eyed).
4. Herkogamy (Herko = barrier)
It is presence of natural and physical barriers between androecium and gynoecium which help in avoiding self pollination e.g., in  Calotropics, gynoecium is fused with pollinium(anthers) and forms gynostegium, Salvia.
5. Self sterility
Pollen fails to germinate on the stigma of same flower due to physiological or genetic reasons e.g., Malva, petunia, Solanum, etc.
6. Pollen prepotency
The condition characterized by rapid germination of foreign pollen instead of self pollen thereby affecting fertilization.
7. Sensitive stigma
In some plants stigmatic lobes are so sensitive that once cross-pollinated, they come closer to prevent self-pollination. e.g., Martynia.

Development of Female Gametophyte:
- The megaspore mother cell undergoes meiosis to form four megaspores.
- Three of them degenerate and the functional megaspore enlarges to form the embryo sac.
- Its haploid nucleus undergoes a mitotic division and the two daughter nuclei move towards the poles.
- Each of them undergoes two successive mitotic divisions.
- Cell wall formation starts in the 8-nucleate stage.
- Three of them at the micropylar end form the egg apparatus, consisting of a female gamete and two synergids.
- Three of them at the chalazal end form the antipodal cells.
- One nucleus from each of the poles moves to the centre; they are called polar nuclei.
- The two polar nuclei fuse in the centre (now the central cell) to form a diploid secondary nucleus.
- Thus, the mature embryo sac is 7-celled and 8-nucleate.

(a) Differences: 

(b) Pollen-Pistil Interaction.
The stigma/pistil has the ability to recognise the right type of pollen, i.e. the compatible pollen of the same species and rejects the wrong type of pollen grains.
It is the result of interaction between the chemical components of the pollen and those of stigma. - A compatible pollen grain starts its germination on the stigma.
The intine grows out through one of the germ pores as a protuberance.
The contents of the pollen move into this tube, i.e. the tube nucleus (nucleus of the vegetative cell) and the generative cell (or the two male gametes in those species where pollen is liberated in the three-celled stage).
The pollen tube grows through the tissues of stigma and style and enters the ovule through micropyle.
It enters the embryo sac through the filiform apparatus of one of the synergids to liberate the male gametes.
The events from the deposition of pollen on the stigma till the pollen tube enters the ovule, are collectively referred to as pollen-pistil interaction.